wdiff rfc7436.alt-original rfc7436.txt

L2VPN Working Group Himanshu
Internet Engineering Task Force (IETF) H. Shah
Internet-Draft Ciena Corp
Intended Status:
Request for Comments: 7436 Cinea Corp.
Category: Historic
Eric E. Rosen
Francois
ISSN: 2070-1721 Juniper Networks
F. Le Faucheur
Giles
G. Heron
Cisco Systems
October 30,
December 2014

IP-Only LAN Service (IPLS)
draft-ietf-l2vpn-ipls-16.txt

Abstract

A Virtual Private LAN Service (VPLS) is used to interconnect systems
across a wide-area or metropolitan-area network, making it appear
that they are on a private LAN. The systems which that are interconnected
may themselves be LAN switches. If, however, they are IP hosts or IP
routers, certain simplifications to the operation of the VPLS are
possible. We call this simplified type of VPLS an "IP-only LAN
Service" (IPLS). In an IPLS, as in a VPLS, LAN interfaces are run in
promiscuous mode, and frames are forwarded based on their destination MAC
Media Access Control (MAC) addresses. However, the maintenance of
the MAC forwarding tables is done via signaling, rather than via the
MAC address learning procedures specified in [IEEE 802.1D]. the IEEE's "Media Access
Control (MAC) Bridges". This draft document specifies the protocol
extensions and procedures for support of the IPLS service.

The original intent was to provide an alternate solution to VPLS for
those PE Provider Edge (PE) routers that were not capable of learning
MAC address addresses through data plane. This became a non-issue with newer
hardware. The concepts put forth by this draft document are still valuable
and are adopted in one form or other by newer work such as Ethernet
VPN in L2VPN Working Group working group and possible data center applications. At
this point, no further action is planned to update this document and
it is published simply as a historic record of the ideas.

Status of this This Memo

This document is not an Internet Standards Track specificaion; specification; it is
published for the historical record.

This document defines a Historic Document for the Internet community.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see section Section 2 of RFC 5741.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6348.

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

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Internet Draft draft-ietf-l2vpn-ipls-16.txt
http://www.rfc-editor.org/info/rfc7436.

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Internet Draft draft-ietf-l2vpn-ipls-16.txt

Table of Contents

Copyright Notice .................................................... 1
Abstract.............................................................. 2
1.0 Contributing Authors ............................................. 3
2.0 Overview.......................................................... 4
2.1

1. Overview ........................................................4
1.1. Terminology ..................................................... 7
3.0 Topology.......................................................... 8
4.0 Configuration..................................................... 9
5.0 Discovery........................................................ 10
5.1 ................................................7
2. Topology ........................................................9
3. Configuration ..................................................10
4. Discovery ......................................................10
4.1. CE discovery ................................................... 10
5.1.1 IPv4 based Discovery ..............................................10
4.1.1. IPv4-Based CE discovery ..................................... 10
5.1.2 Ipv6 based Discovery ............................11
4.1.2. IPv6-Based CE discovery [RFC 4861] .......................... 10
6.0 Pseudowire Creation.............................................. 11
6.1 Discovery (RFC 4861) .................11
5. PW Creation ....................................................11
5.1. Receive Unicast Multipoint-to-point Pseudowire ................. 11
6.2 Multipoint-to-Point PW ....................11
5.2. Receive Multicast Multipoint-to-point Pseudowire ............... 11
6.3 PW ..................12
5.3. Send Multicast Replication tree ................................ 12
7.0 Signaling........................................................ 13
7.1 Tree ...........................13
6. Signaling ......................................................13
6.1. IPLS PW Signaling .............................................. 13
7.2 .........................................13
6.2. IPv6 Capability Advertisement .................................. 17
7.3 .............................17
6.3. Signaling Advertisement Processing ............................. 18
8. ........................18
7. IANA Considerations............................................... 19
8.1. Considerations ............................................19
7.1. LDP Status messages ........................................... 19
8.2. Messages .......................................19
7.2. Interface Parameters .......................................... 19
9.0 Forwarding....................................................... 19
9.1 ......................................19
8. Forwarding .....................................................20
8.1. Non-IP or non-ARP traffic ...................................... 19
9.2 Non-ARP Traffic .................................20
8.2. Unicast IP Traffic ............................................. 20
9.3 ........................................20
8.3. Broadcasts and Multicast IP Traffic ............................ 20
9.4 .......................20
8.4. ARP Traffic .................................................... 20
9.6 ...............................................21
8.5. Discovery of IPv6 CE Devices ..............................21
8.5.1. Processing of Neighbor Solicitations ...............22
8.5.2. Processing of Neighbor Advertisements ..............22
8.5.3. Processing of Inverse Neighbor
Solicitations and Advertisement ....................22
8.5.4. Processing of Router Solicitations and
Advertisements .....................................23
8.6. Encapsulation .................................................. 23
10.0 .............................................23
9. Attaching to IPLS via ATM or FR............................... 23
11.0 Frame Relay (FR) ..................24
10. VPLS vs IPLS.................................................... 23
12.0 IP Protocols.................................................... 24
13.0 Dual Homing with IPLS........................................... 25
14.0 vs. IPLS .................................................24
11. IP Protocols ..................................................25
12. Dual-Homing with IPLS .........................................25
13. Proxy ARP function.............................................. 25
14.1 Function ............................................26
13.1. ARP Proxy - Responder ......................................... 25
14.2 ....................................26
13.2. ARP Proxy - Generator ......................................... 25
15.0 ....................................26
14. Data Center Applicability ...................................... 25
16.0 Acknowledgements................................................ 26
17.0 .....................................27
15. Security Considerations......................................... 27
17.1 Control plane security ........................................ 27
17.2 Data plane security ........................................... 28
18.0 References...................................................... 29
18.1 Considerations .......................................27
15.1. Control-Plane Security ...................................27
15.2. Data-Plane Security ......................................28
16. References ....................................................29
16.1. Normative References .......................................... 29
18.2 .....................................29
16.2. Informative References ........................................ 29
19.0 Author's Address................................................ 30

2.0 ...................................30
Acknowledgements ..................................................31
Contributors ......................................................31
Authors' Addresses ................................................32

1. Overview

As emphasized in [VPLS], Ethernet has become popular as an access
technology in Metropolitan metropolitan- and Wide Area Networks. wide-area networks. [VPLS] describes
how geographically dispersed customer LANs can be interconnected over
a service provider's network. The VPLS service is provided by
Provider Edge (PE) devices that connect Customer Edge (CE) devices.
The VPLS architecture provides this service by incorporating bridging
functions such as MAC address learning in the PE devices.

Provider Edge

PE platforms are designed primarily to be IP routers, routers rather than to be LAN
switches. To add VPLS capability to a PE router, one has to add MAC address learning MAC-
address-learning capabilities, along with aging and other mechanisms
native to Ethernet switches. This may be fairly complex to add to
the forwarding plane forwarding-plane architecture of an IP router. As discussed in
[L2VPN-FWK], in scenarios where the CE devices are NOT LAN switches,
but rather are IP hosts or IP routers, it is possible to provide the
VPLS service without requiring MAC address learning and aging on the
PE. Instead, a PE router has to have the capability to match the
destination MAC address in a packet received from a CE to an outbound pseudowire.
PW. The requirements for the IPLS service are described in
[L2VPN-REQTS]. The purpose of this document is to specify a solution
optimized for IPLS.

IPLS provides a VPLS-like service using PE routers that are not
designed to perform general LAN bridging functions. One must be
willing to accept the restriction that an IPLS be used for IP traffic
only, and not used to interconnect CE devices that are themselves LAN
switches. This is an acceptable restriction in many environments,
given that IP is the predominant type of traffic in today's networks.

The original intent was to provide an alternate solution to VPLS for
those PE routers that were not capable of learning MAC address addresses
through the data plane. This became a non-issue with newer hardware.
The concepts put forth by this draft document are still valuable and are
adopted in one form or other by newer work such as Ethernet VPN in L2VPN Working Group
the LVPN working group and possible data center applications. At
this point, no further action is planned to update this document and
is published simply as a historic record of the ideas.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

In IPLS, a PE device implements multi-point multipoint LAN connectivity for IP
traffic using the following key functions:

1. CE Address Discovery: Each Provider Edge (PE) PE device discovers the MAC address
of the locally attached Customer Edge (CE) CE IP devices, for each IPLS instance
configured on the PE device. In some configurations, the PE
also learns the IP address of the CE device (when performing
ARP proxy functions, described later in the document).

2. Pseudowire (PW) for Unicast Traffic: For each locally attached
CE device in a given IPLS instance, a PE device sets up a
pseudowire (PW-LSP) to each of the other PEs that supports the
same IPLS instance.

For instance, if PEx and PEy both support IPLS I, and PEy is
locally attached to CEa and CEb, PEy will initiate the setup of
two pseudowires PWs between itself and PEx. One of these will be used to
carry unicast traffic from any of PEx's CE devices to CEa. The
other will be used to carry unicast traffic from any of PEx's
CE devices to CEb.

Note that these pseudowires PWs carry traffic only in one direction.
Further, while the pseudowire PW implicitly identifies the destination CE
of the traffic, it does not identify the source CE; packets
from different source CEs bound to the same destination CE are
sent on a single pseudowire. PW.

3. Pseudowires for Multicast Traffic: In addition, every PE
supporting a given IPLS instance will set up a special
'multicast pseudowire' to every other PE in that IPLS instance.
If, in the above example, one of PEx's CE devices sends a
multicast packet, PEx would forward the multicast packet to PEy
on the special 'multicast' pseudowire. PEy would then send a
copy of that packet to CEa and a copy to CEb.

The 'multicast' pseudowire carries Ethernet frames of
multicast/broadcast IP, ARP ARP, and ICMP (Inverse) Neighbor
Discovery (ND/IND) packets for IPv6. Thus Thus, when a PE sends a
multicast packet across the network, it sends one copy to each
remote PE (supporting the given IPLS instance). If a
particular remote PE has more than one CE device in that IPLS
instance, the remote PE must replicate the packet and send one
copy to each of its local CEs.

As with the pseudowires that are used for unicast traffic,
packets travel in only one direction on these pseudowires, and
packets from different sources may be freely intermixed.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

4. Signaling: The necessary pseudowires can be set up and
maintained using the LDP-based signaling procedures based on the Label
Distribution Protocol (LDP) described in [PWE3-CONTROL].

A PE may assign the same label to each of the unicast
pseudowires that lead to a given CE device, in effect creating
a multipoint-to-point pseudowire.

Similarly, a PE may assign the same label to each of the
'multicast' pseudowires for a given IPLS instance, in effect
creating a multipoint-to-point pseudowire. When setting up a
pseudowire to be used for unicast traffic, the PE must also
signal the MAC address of the corresponding CE device. It
should also, optionally, advertise the IP address of the local
CE device, especially when ARP proxy function is configured or
simply for operational management purposes. Similarly, for
IPv6 support, PE may optionally advertise the IPv6 addresses of
the local CE device.

5. ARP Packet Forwarding: ARP packets [ARP] are forwarded from the
attachment circuit (AC) to 'multicast' pseudowires in the
Ethernet frame format as described by [PWE3-ETH].The [PWE3-ETH]. The
following rules are observed when processing ARP packets, packets:

a. Both broadcast (request) and unicast (response) ARP packets
are sent over the 'multicast' pseudowire.

b. When an ARP packet is received from an AC, the packet is
copied to the control plane for the purpose of learning the
MAC address of the CE. Optionally, an IP address is also
learned to record the association of the IP and MAC address.

c. All Ethernet packets, including ARP packets, received from
the 'multicast' pseudowire are forwarded out to all the ACs
associated with the IPLS instance. These packets are not
copied to the control plane.

6. ICMP IPv6 ND/IND related ND/IND-related Packet Forwarding: (Inverse) Neighbor
Discovery (ND/IND) ND/IND IPv6 packets
from an AC are replicated and a copy is sent to other ACs and
to 'multicast' PWs associated with the IPLS instance in the
native Ethernet format, unchanged. A copy is also submitted to Control Plane
the control plane to learn the MAC address and optionally and, optionally,
corresponding IPv6 addresses.

7. Multicast IP packet forwarding: An IP Ethernet frame received
from an AC is replicated to other ACs and the 'multicast'
pseudowires PWs
associated with the IPLS instance. An IP Ethernet frame
received from a 'multicast' pseudowire PW is replicated to all the egress
ACs associated with the IPLS instance.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

8. Unicast IP packet forwarding: An IP packet received from the AC
is forwarded based on the MAC DA Destination Address (DA) lookup
in the forwarding table. If a match is found, the packet is
forwarded to the associated egress interface. If the egress
interface is unicast
pseudowire, PW, the packet is sent without a MAC
header. If the egress interface is a local AC AC, the Ethernet
frame is forwarded as such. An IP packet received from the
unicast pseudowire PW is forwarded to the egress AC with the MAC header
prepended. The MAC DA is derived from the forwarding table
while the MAC SA Source Address (SA) is the MAC address of the PE.

Both VPLS [VPLS] and IPLS require the ingress PE to forward a frame
based on its destination MAC address. However, two key differences
between VPLS and IPLS can be noted from the above description:

- In VPLS, MAC entries are placed in the Forwarding Information Base
(FIB) of the ingress PE as a result of MAC address learning (which
occurs in the data plane) while plane); whereas, in IPLS IPLS, MAC entries are
placed in the FIB as a result of pseudowire PW signaling operations (control
plane).
.

- In VPLS, the egress PE looks up a frame's destination MAC
address DA to determine the
egress AC; in IPLS, the egress AC is determined entirely by the
ingress PW-label.

The following sections describe the details of the IPLS scheme.

2.1

1.1. Terminology

Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119. [RFC2119].

IPLS IPLS stands for IP-only LAN service (a type of Virtual
Private LAN Service that is restricted to IP traffic
only).

mp2p

MP2P PW Multipoint-to-Point Pseudowire. A pseudowire Pseudowire is a PW that carries
traffic from remote PE devices to a PE device that
signals the pseudowire. PW. The signaling PE device advertises
the same PW-
label PW-label to all remote PE devices that
participate in the IPLS service instance. In IPLS,
for a given IPLS instance, an mp2p MP2P PW used for IP
unicast traffic is established by a PE for each CE
device locally attached to that PE. It is a
unidirectional tree whose leaves consist of the remote
PE peers (which connect at least one AC associated
with the same IPLS instance) and whose root is the
signaling PE. Traffic flows from the leaves towards
the root.

Multicast PW Multicast/broadcast Pseudowire. A Pseudowire is a special kind of mp2p
MP2P PW that carries IP multicast/broadcast traffic,
all ARP frames and ICMP (I)ND frames for IPv6. In the
IPLS architecture, for each IPLS instance supported by
a PE, that PE device establishes exactly one multicast
PW. Multicast PW uses Ethernet encapsulation.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

Unicast PW Unicast Pseudowire pseudowire carries IP unicast packets. A PE
creates unicast PW for each locally attached CE. The
unicast PW uses IP Layer2 Layer 2 (L2) transport
encapsulation.

CE Customer Edge device. In this document, a CE Customer Edge (CE) is any IP node
(host or router) connected to the IPLS LAN service.

Replication Tree The collection of all multicast PWs and ACs
Tree that are members of an IPLS service instance on a
given PE. When a PE receives a multicast/broadcast
packet from an AC, the PE device sends a copy of the
packet to every multicast pseudowire PW and AC of the replication
tree, excluding the AC on which the packet was
received. When a PE receives a packet from a
multicast PW, the PE device sends a copy of the packet
to all the ACs of the replication tree and never to
other PWs.

(I)ND (Inverse) Neighbor Discovery in IPv6 uses ICMP
packets. It is a protocol that uses Neighbor
solicitation/Advertisement
Solicitation (NS) / Neighbor Advertisement (NA) PDUs.

RS Router Solicitation. Hosts Solicitation is when hosts generate all router
multicast ICMP packet packets to discover the IPv6 router on
the local link.

RA Router Advertisement. Router Advertisement occurs when a router generates
all multicast ICMP packet packets to advertise its presence
on the link. A unicast response is also sent when RS
is received.

NS Neighbor Solicitation in IPv6 uses (multicast) ICMP
packets to resolve the association of the IPv6
interface address to the MAC address association. address.

NA Neighbor Advertisement in IPv6 uses (unicast) ICMP
packets to respond to NS.

3.0

2. Topology

The Customer Edge (CE) CE devices are IP nodes (hosts or routers) that are connected to
PE devices either directly, directly or via an Ethernet network. We assume
that the PE/CE connection may be regarded by the PE as an "interface"
to which one or more CEs are attached. This interface may be a
physical LAN interface or a VLAN. The Provider
Edge (PE) PE routers are MPLS Label Edge
Routers (LERs) that serve as
pseudowire PW endpoints.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

+----+ +----+
+ S1 +---+ ........................... +---| S2 |
+----+ | | . . | +----+
IPa | | +----+ +----+ | IPe
+ +---| PE1|---MPLS and/or IP---| PE2|---+
/ \ +----+ |Network +----+ |
+----+ +---+ . | . | +----+
+ S1 + | S1| . +----+ . +---| S2 |
+----+ +---+ ..........| PE3|........... +----+
IPb IPc +----+ IPf
|
|
+----+
| S3 |
+----+
IPd

In the above diagram, an IPLS instance is shown with three sites:
site S1, site S2 S2, and site S3. In site S3, the CE device is directly
connected to its PE. In the other two sites, there are multiple CEs
connected to a single PE. More precisely, the CEs at these sites are
on an Ethernet (switched at site 1 and shared at site 2) network (or
VLAN), and the PE is attached to that same Ethernet network or VLAN).
We impose the following restriction: if one or more CEs attach to a
PE by virtue of being on a common LAN or VLAN, there MUST NOT be more
than one PE on that LAN or VLAN.

PE1, PE2 PE2, and PE3 are shown as connected via an MPLS network;
however, other tunneling technologies, such as GRE, L2TPv3, Generic Routing
Encapsulation (GRE), Layer 2 Tunneling Protocol version 3 (L2TPv3),
etc., could also be used to carry the pseudowires. PWs.

An IPLS instance is a single broadcast domain, such that each IP end
station (e.g., IPa) appears to be co-located with other IP end
stations (e.g., IPb through IPf) on the same subnet. The IPLS
service is transparent to the CE devices and requires no changes to
them.

4.0

3. Configuration

Each PE router is configured with one or more IPLS service instances,
and each IPLS service instance is associated with a unique VPN-Id.
For a given IPLS service instance, a set of ACs is identified. Each
AC can be associated with only one IPLS instance. An AC, in this
document, is either a customer-facing Ethernet port, or a particular
VLAN (identified by an IEEE 802.1Q VLAN ID) on a customer-facing
Ethernet port.

The PE router can optionally be configured with a local MAC address
to be used as a source MAC address when IP packets are forwarded from
Internet Draft draft-ietf-l2vpn-ipls-16.txt
a pseudowire PW to an AC. By default, a PE uses the MAC address of the
customer-facing Ethernet interface for this purpose.

5.0

4. Discovery

The discovery process includes:
.
- Remote PE discovery
.
- VPN (i.e., IPLS) membership discovery
.
- IP CE end station discovery

This draft document does not discuss the remote PE discovery or VPN
membership discovery. This information can either be user configured
or can be obtained using auto-discovery techniques described in
[L2VPN-SIG] or other methods. However, the discovery of the CE is an
important operational step in the IPLS model and is described below.

5.1

4.1. CE discovery Discovery

Each PE actively detects the presence of local CEs by snooping IP and
ARP frames received over the ACs. When an AC configured in an IPLS
instance becomes operational, it enters the CE discovery phase. In
this phase, the PE examines each multicast/broadcast Ethernet frame.
For link-local IP frames (for example example, IGP
discovery/multicast/broadcast packets typically 224.0.0.x addresses
[RFC-1112]),
[RFC1112]), the CE's (source) MAC address is extracted from the
Ethernet header and the (source) IP address is obtained from the IP
header.

For each CE, the PE maintains the following tuple: <Attachment
Circuit identification info, VPN-Id, MAC address, IP address
(optional)>.

5.1.1 IPv4 based

4.1.1. IPv4-Based CE discovery Discovery

As indicated earlier, a copy of ARP frames received over the AC is
submitted to the control plane. The PE learns the MAC address and
optionally the IP address of the CE from the source address fields of
the ARP PDU.

Once a CE is discovered, its status is monitored continuously by
examining the received ARP frames and by periodically generating ARP
requests. The absence of an ARP response from a CE after a
configurable number of ARP requests is interpreted as loss of
connectivity with the CE.

5.1.2 Ipv6 based

4.1.2. IPv6-Based CE discovery [RFC 4861] Discovery (RFC 4861)

A copy of Neighbor and Router Discovery frames received over the AC
are submitted to the control plane in the PE.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

If the PE receives a Neighbor Solicitation an NS message, and the source IP address of the
message is not the unspecified address, the PE learns the MAC address
and optionally the IP address of the CE.

If the PE receives an unsolicited Neighbor Advertisement NA message, the PE learns the
source MAC address and optionally the IP address of the CE.

If the PE receives a Router Solicitation, an RS, and the source IP address of the message is
not the unspecified address, the PE learns source MAC address and
optionally the IP address of the CE.

If the PE receives a Router Advertisement, an RA, it learns the source MAC address and
optionally the IP address of the CE.

The PE will periodically generate Neighbor Solicitation NS messages for the IP address of
the CE as a means of verifying the continued existence of the address
and its MAC address binding. The absence of a response from the CE
device for a given number of retries could be interpreted as a loss
of connectivity with the CE.

6.0 Pseudowire

5. PW Creation

6.1

5.1. Receive Unicast Multipoint-to-point Pseudowire Multipoint-to-Point PW

As the PE discovers each locally attached CE, a unicast multipoint-
to-point pseudowire (mp2p (MP2P PW) associated exclusively with that CE is
created by distributing the MAC address and optionally the IP address
of the CE along with a PW-Label to all the remote PE peers that
participate in the same IPLS instance. Note that the same value of a
PW-label SHOULD be distributed to all the remote PE peers for a given
CE. The mp2p MP2P PW thus created is used by remote PEs to send unicast
IP traffic to a specific CE.

(The same functionality can be provided by a set of point-to-point
PWs, and the PE is not required to send the same PW-label to all the
other PEs. For convenience, however, we will use the term mp2p MP2P PWs,
which may be implemented using a set of point-to-point PWs.)

The PE forwards a frame received over this mp2p MP2P PW to the associated
AC.

The unicast pseudowire PW uses IP Layer2 Layer 2 Transport encapsulation as
define defined in
[PWE3-CONTROL].

6.2

5.2. Receive Multicast Multipoint-to-point Pseudowire Multipoint-to-Point PW

When a PE is configured to participate in an IPLS instance, it
advertises a 'multicast' PW-label to every other PE that is a member
Internet Draft draft-ietf-l2vpn-ipls-16.txt
of the same IPLS. The advertised PW-label value is the same for each
PE, which creates an mp2p pseudowire. MP2P PW. There is only one such multicast mp2p MP2P
PW per PE for each IPLS instance instance, and this pseudowire PW is used exclusively to
carry IP multicast/broadcast, ARP traffic traffic, and (inverse) Neighbor
Discovery packets for IPv6 from the remote PEs to this PE for this
IPLS instance.

Note that no special functionality is expected from this pseudowire. PW. We call
it a 'multicast' pseudowire PW because we use it to carry multicast and
broadcast IP, ARP ARP, and IPv6 Neighbor Discovery traffic. The pseudowire PW
itself need not provide any different service than any of the unicast pseudowires.
PWs.

In particular, the Receive multicast mp2p MP2P PW does not perform any
replication of frames itself. Rather, it is there to signify to the
PE that the PE may need to replicate a copy of a frame received over
this mp2p MP2P PW onto all the AC ACs that are associated with the IPLS
instance of the mp2p MP2P PW.

The multicast mp2p pseudowire MP2P PW is considered the principle pseudowire PW in the bundle of mp2p pseudowires
MP2P PWs that consist consists of one multicast mp2p
pseudowire MP2P PW and a variable number
of unicast mp2p pseudowires MP2P PWs for a given IPLS instance. In a principle role,
multicast PW represents the IPLS instance. The life of all unicast
PWs in the IPLS instance depends on the existence of the multicast
PW. If, for some reasons, reason, multicast PW PWs cease to exist, all the
associated unicast pseudowires PWs in the bundle are would be removed.

The multicast pseudowire PW uses Ethernet encapsulation as defined in
[PWE3-ETH].

The use of pseudowires which PWs that are specially optimized for multicast is for
further study.

6.3

5.3. Send Multicast Replication tree Tree

The PE creates a send replication tree for each IPLS instance, which
consists of the collection of all ACs and all the 'multicast'
pseudowires PWs of
the IPLS instance.

Any ARP, Neighbor Discovery Discovery, or multicast IP Ethernet frame received
over an AC is replicated to the other ACs and to the mp2p MP2P multicast
pseudowire
PW of the send replication tree. The send replication tree deals
mostly with broadcast/multicast Ethernet MAC frames. One exception
to this is unicast ARP and IPv6 Neighbor Discovery frame, the
processing of which is described in the following section.

Any Ethernet frame received over the multicast PW is replicated to
all the ACs of the send replication tree of the IPLS instance
associated with the incoming PW label. One label: one exception is unicast ARP
Internet Draft draft-ietf-l2vpn-ipls-16.txt
and Neighbor Discovery frame frames used for IPv6, the processing of which
is described in the following section.

7.0

6. Signaling

[PWE3-CONTROL] uses the Label Distribution Protocol (LDP) LDP to exchange PW-FECs in the Label Mapping
message in a downstream unsolicited mode. The PW-FEC comes in two
forms; PWid and Generalized PWid FEC elements. These FEC elements
define some fields that are common between them. The discussions
below refer to these common fields for IPLS related IPLS-related extensions. Note
that the use of
multipoint to point multipoint-to-point and unidirectional
characteristics of the PW makes BGP as the ideal candidate for PW-FEC
signaling. The use of BGP for such purposes is for future study.

7.1

6.1. IPLS PW Signaling

An IPLS carries IP packets as payload over its unicast pseudowires PWs and
Ethernet packet packets as payload over its multicast pseudowire. PW. The PW-type to be
used for unicast pseudowire PW is the IP PW, defined in [PWE3-CONTROL] as IP Layer2
Layer 2 Transport. The PW-type to be used for multicast pseudowire PW is the
Ethernet PW as defined in [PWE3-ETH]. The PW-Type values for these
encapsulations are defined in [PWE3-
IANA]. [PWE3-IANA].

When processing a received PW FEC, the PE matches the PW Id with the
locally configured PW Id for the IPLS instance. If the PW type is
Ethernet, the PW-FEC is for multicast PW. PWs. If the PW type is 'IP
Layer2
Layer 2 transport', the PW FEC is for unicast PW. PWs.

For unicast PW, PWs, the PE must check the presence of a MAC address Address TLV
in the optional parameter fields of the Label Mapping message. If
this parameter is absent, a Label Release message must be issued with
a Status Code meaning "MAC Address of the CE is absent" [note: (note: Status
Code 0x000000XX is pending IANA allocation], allocation), to reject the
establishment of the unicast PW with the remote PE.

The PE may optionally include an IP address TLV based on the user
configuration for the advertising of the IP addresses of the local
CE.

The processing of the address list Address List TLV is as follows.

o If a pseudowire PW is configured for AC ACs with IPv4 CEs only, the PE should
advertise address list tlv an Address List TLV with an address family type
to be of an
IPv4 address. The PE should process the IPv4 address list TLV
as described in this document.

o If a pseudowire PW is configured for AC ACs with both IPv4 and IPv6 CEs, the
PE should advertise IPv6 capability using the procedures
described in Section the section below.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

o If a PE does not receive any IP address list Address List TLV or IPv6
capability advertisement, it MAY assume IPv4 behavior.

The IPLS uses the Address List TLV as defined in [RFC 5036] [RFC5036] to signal
the MAC (and optionally IP) address of the local CE. There are two
TLVs defined below; below: the IP Address TLV and MAC Address TLV. The MAC
address
Address TLV must be included in the optional parameter field of the
Label Mapping message when establishing the unicast IP PW for IPLS.

When configured to support a specific type of IP traffic (IPv4 or
IPv6), the PE augments verification of the type of traffic PW will
carry using the Address Family Type value. If there is a mismatch
between the received Address Family value and the expectation of an
IPLS instance to which the PW belongs, the PE must issue a Label
Release message with a Status Code meaning "IP Address type mismatch"
(Status Code 0x0000004A) to reject the PW establishment.

Encoding

The encoding of the IP Address TLV is: is as follows:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0| Address List (0x0101) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Family | CE's IP Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CE's IP Address | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Length
When an Address Family is IPV4, IPv4, the Length is equal to 6 bytes; 2
bytes for address family the Address Family and 4 bytes of IP address. The
length
Length is 18 bytes when address family the Address Family is IPv6, IPv6; 2 bytes for
address family
the Address Family and 16 bytes of IP address.

Address Family
Two octet
Two-octet quantity containing a value from the ADDRESS FAMILY
NUMBERS from ADDRESS FAMILY NUMBERS in "Address Family
Numbers" registry [ADDR-IANA] that encodes the addresses contained
in the Addresses field.

IP Address of the CE
IP address of the CE attached to the advertising PE. The encoding
of the individual address depends on the Address Family.

The following address encodings are defined by this version of the
protocol:

Address Family Address Encoding

IPv4 (1) 4 octet 4-octet full IPv4 address
Internet Draft draft-ietf-l2vpn-ipls-16.txt

IPv6 (2) 16 octet 16-octet full IPv6 address

Note that more than one instance of the IP address TLV may exist,
especially when support for IPv6 is configured.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

Encoding

The encoding of the MAC Address TLV is: is as follows:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0| Address List (0x0101) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Family | CE's MAC address Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Length
The length Length field is set to a value of 8 (2 bytes for address family, the Address
Family, 6 bytes for the MAC address)

Address Family
Two octet
Two-octet quantity containing a value from ADDRESS FAMILY
NUMBERS in the "Address Family
Numbers" registry [ADDR-IANA] that encodes the addresses contained
in the Addresses field.

CE's MAC Address
MAC address of the CE attached to the advertising PE. The
encoding of the individual address depends on the Address Family.

The following address encodings are defined by this version of the
protocol:

Address Family Address Encoding

MAC (6) 6 octet 6-octet full Ethernet MAC address

The IPv4 address of the CE is also supplied in the optional
parameters field of the LDP Notification message along with the PW
FEC. The LDP Notification message is used to signal any change in
the status of the CE's IPv4 address.

Note that Notification message does not apply to the MAC address Address TLV
since an update to the MAC address of the CE should result in label
withdraw
withdrawal followed by establishment of a new PW with a new MAC
address of the CE. However, advertisement of IP address(es) of the
CE is
optional optional, and changes may become known after the establishment
of unicast PW.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

The encoding of the LDP Notification message is as follows.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Notification (0x0001) | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status (TLV) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address List TLV (as defined above) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PWId FEC or Generalized ID FEC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The Status TLV status code is set to 0x0000002C "IP address of CE",
to indicate that an IP Address address update follows. Since this
notification does not refer to any particular message message, the Message Id, ID
and Message Type fields are set to 0.

The PW FEC TLV SHOULD NOT include the interface parameters as they
are ignored in the context of this message.

7.2

6.2. IPv6 Capability Advertisement

A 'Stack Capability' Interface Parameter sub-TLV is signaled by the
two PEs so that they can agree which stack(s) they should be using.
It is assumed assumed, by default default, that the IP PW will always be capable of
carrying IPv4 packets. Thus Thus, this capability sub-TLV is used to
indicate if other stacks need to be supported concurrently with IPv4.

The 'Stack Capability' sub-TLV is part of the interface parameters of
the PW FEC. The proposed format for the Stack Capability
interface parameter 'Stack Capability' Interface
Parameter sub-TLV is as follows:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter ID | Length | Stack Capability |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parameter ID = 0x16

Length = 4

Stack capability Capability = 0x000X to indicate IPv6 stack capability
Internet Draft draft-ietf-l2vpn-ipls-16.txt
The Value value of Stack capability Capability is dependent on the PW type context.
For IP PW type, a setting of 0x000X indicates IPv6 stack capability.

A PE that supports IPv6 on an IP PW MUST signal the stack capability 'Stack
Capability' sub-TLV in the initial label mapping Label Mapping message for the PW.
The PE nodes compare the value advertised by the remote PE with the
local configuration and only use a capability which that is advertised by
both. If a PE that supports IPv6 does not receive a 'stack capability' 'Stack
Capability' sub-TLV from the far-end PE in the initial label mapping Label Mapping
message, or one is received but it is set to a reserved value, the PE
MUST send an unsolicited release for the PW label with the LDP status
code meaning "IP Address type mismatch" (Status Code 0x0000004A).

The behavior of a PE that does not understand an interface parameter
sub-TLV is specified in RFC4447 RFC 4447 [PWE3-CONTROL].

7.3

6.3. Signaling Advertisement Processing

A PE should process a received [PWE3-CONTROL] advertisement with PW-
type a
PW-type of IP Layer2 transport Layer 2 Transport for IPLS as follows, follows:

- Verify the IPLS VPN membership by matching the VPN-Id signaled
in the AGI Attachment Group Identifier (AGI) field or the PW-ID
field with all the VPN-Ids configured in the PE. Discard and
release the PW label if VPN-Id is not found.

- Program the Forwarding Information Base (FIB) FIB such that when a unicast IP packet is received
from an AC with its destination MAC address matching the
advertised MAC address, the packet is forwarded out over the
tunnel to the advertising PE with the advertised PW-label as
the inner label.

A PE should process a received [PWE3-CONTROL] advertisement with the
PW type of Ethernet for IPLS as follows, follows:

- Verify the IPLS VPN membership by matching the VPN-Id signaled
in the AGI field or the PW-ID field with all the VPN-Ids
configured in the PE. Discard and release the PW label if VPN-Id VPN-
Id is not found.

- Add the PW-label to the send broadcast replication tree for the
VPN-Id. This enables the sending of a copy of a
multicast/broadcast IP Ethernet frame or frame, ARP Ethernet frame frame, or
Neighbor Discovery frames from the AC to this pseudowire.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

8. PW.

7. IANA Considerations

Since this document is being published as historic record, Historic, no
requests for registration
of IANA code points are necessary. However, if in the future, if
interest to pursue this proposal arises, the following
requests for IANA codes code
registrations would become necessary.

8.1.

7.1. LDP Status messages Messages

This document uses a new LDP status code. Status Code. IANA already maintains a the
"Status Code Name Space" registry of name "STATUS CODE NAME SPACE" defined by [RFC 5036]. [RFC5036]. The
following value is would be suggested for assignment:

0x000000XX "MAC Address of CE is absent"

8.2.

7.2. Interface Parameters

This document proposes a new Interface Parameters sub-TLV, to be
assigned from the 'Pseudowire "Pseudowire Interface Parameters Sub-TLV type
Registry'.
Registry". The following value is would be suggested for the Parameter
ID:

0xXX "Stack capability" Capability"

IANA is would also be requested to set up a registry of an "L2VPN PE stack
capabilities". Stack
Capabilities" registry. This is a 16 bit 16-bit field. The Stack capability values
0x000X
Capability value (0x000X) is specified in Section 7. 6.2 of this
document. The remaining
bitfield bit field values (0x0002,..,0x8000) are to would be
assigned by IANA using the "IETF Consensus" policy defined in [RFC 5226].
[RFC5226].

L2VPN PE Stack Capabilities:

Bit (Value) Description
=============== ==========================================
Bit 0 (0x000X) - IPv6 stack capability
Bit 1 (0x000X) - Reserved
Bit 2 (0x000X) - Reserved
.
.
.
Bit 14 (0xX000) - Reserved
Bit 15 (0xX000) - Reserved

9.0

8. Forwarding

9.1

8.1. Non-IP or non-ARP traffic Non-ARP Traffic

In an IPLS VPN, a PE forwards only IP and ARP traffic. All other
frames are dropped silently. If the CEs must pass non-IP traffic to
each other, they must do so through IP tunnels that terminate at the
CEs themselves.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

9.2

8.2. Unicast IP Traffic

In IPLS, IP traffic is forwarded from the AC to the PW based on the
destination MAC address of the layer 2 L2 frame (and not based on the IP Header).
header).

The PE identifies the FIB associated with an IPLS instance based on
the AC or the PW label. When a frame is received from an AC, the PE
uses the destination MAC address as the lookup key. When a frame is
received from a PW, the PE uses the PW-Label as the lookup key. The
frame is dropped if the lookup fails.

For IPv6 support, the unicast IP ICMP frame of Neighbor Discovery
Protocol [RFC 4861] [RFC4861] is bi-casted; one copy is submitted to the control
plane and other copy to the PW, based on the destination MAC address.

9.3

8.3. Broadcasts and Multicast IP Traffic

When the destination MAC address is either a broadcast or multicast, a
copy of the frame is sent to the control plane for CE discovery
purposes (see section 5.1). Section 4.1). It is important to note that stricter
rate-limiting criteria is applied to frames sent to the control
plane, in order to avoid overwhelming it under adverse conditions
such as Denial of Service attack. Denial-of-Service (DoS) attacks. The service provider should
also provide a configurable limitation to prevent the overflowing of
the learned source addresses in a given IPLS instance. Also, caution
must be used such that only link local link-local multicasts and broadcast IP
packets are sent to the control plane.

When a multicast/broadcast IP packet is received from an AC, the PE
replicates it onto the Send Multicast Replication Tree (See section
6.3). (see Section
5.3). When a multicast/broadcast IP Ethernet frame is received from
a pseudowire, PW, the PE forwards a copy of the frame to all the ACs associated
with the respective IPLS VPN instance. Note that 'multicast' PW uses
Ethernet encapsulation and hence encapsulation; hence, it does not require additional header
manipulations.

9.4

8.4. ARP Traffic

When a broadcast ARP frame is received over the AC, a copy of the
frame is sent to the control plane for CE discovery purposes. The PE
replicates the frame onto the Send Multicast Replication Tree (see
section 6.3),
Section 5.3), which results into in a copy to be delivered to all the
remote PEs on the 'multicast' PW and other local CEs through the
egress ACs.

When a broadcast Ethernet ARP frame is received over the 'multicast'
PW, a copy of the Ethernet ARP frame is sent to all the ACs
associated with the IPLS instance.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

When a unicast Ethernet ARP frame is received over the AC, a copy of
the frame is sent to the control plane for CE discovery purposes.
The PE may optionally do MAC DA lookup in the forwarding table and
send the ARP frame to a specific egress interface (AC or 'multicast'
PW to a remote PE) or replicate the frame onto the Send Multicast
Replication Tree (see section 6.3). Section 5.3).

When a unicast ARP Ethernet frame is received over the 'multicast'
PW, the PE may optionally do MAC DA lookup in the forwarding table
and forward it to the AC where the CE is located. If the CE is not
accessible through any local AC, the frame is dropped. Conversely,
the PE may simply forward the frame to all the ACs associated with
that IPLS instance without any lookup in the forwarding table.

9.5

8.5. Discovery of IPv6 CE devices Devices

A PE device that supports IPv6 MUST be capable of, of:

- Intercepting ICMPv6 Neighbor Discovery [RFC 4861] [RFC4861] packets
received over the AC.

- Record Recording the IPv6 interface addresses and CE link-layer
addresses present in these packets

- Forward Forwarding them towards the original destination destination. A PE device
may also intercept Router Discovery packets in order to
discover the link layer link-layer address and IPv6 interface address(es)
of the CE. Following The following sections describe the details.

The PE device MUST learn the link-layer address of the local CE and
be able to use it when forwarding traffic between CEs. The PE MAY
also wish to monitor the source link-layer address of data packets
received from the CE, CE and discard packets not matching its learned CE
link-layer address. The PE device may also optionally learn a list
of CE IPv6 interface addresses for its directly-attached directly attached CE.

9.5.1.

8.5.1. Processing of Neighbor Solicitations

When a broadcast Neighbor Solicitation NS frame is received over the AC, a copy of the
frame is sent to the control plane for CE discovery purposes. The PE
replicates the frame onto the Send Multicast Replication Tree (see section 6.3),
Section 5.3), which results in a copy to be delivered to all the
remote PEs on the 'multicast' PW and other local CEs through the
egress ACs. The PE may optionally learn an IPv6 interface address
(If provided - -- this will not be the case for Duplicate Address
Detection) when present.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

When a broadcast Ethernet Neighbor Solicitation NS frame is received over the 'multicast'
PW, a copy is sent to all the ACs associated with the IPLS instance.

9.5.2

8.5.2. Processing of Neighbor Advertisements

When a unicast Neighbor Advertisement NA is received over the AC, a copy of the frame is
sent to the control plane for the CE discovery purposes. The PE may
optionally do MAC DA lookup in the forwarding table and send the Neighbor Advertisement NA
frame to a specific egress interface (AC or 'multicast' PW to a
remote PE) or replicate the frame onto the Send Multicast Replication
Tree (see section 6.3). Section 5.3).

Optionally, the PE could learn the IPv6 Interface address of the CE.

When a unicast Neighbor Advertisement NA frame is received over the 'multicast' PW, the PE
may optionally do MAC DA lookup in the forwarding table and forward
it to the AC where the CE is located. If the CE is not accessible
through any local AC, the frame is dropped. Conversely, the PE may
simply forward the frame to all the ACs associated with that IPLS
instance without any lookup in the forwarding table.

9.5.3

8.5.3. Processing of Inverse Neighbor Solicitations and Advertisement

Inverse Neighbor Discovery is typically used on non-broadcast links,
but are is allowed on broadcast links too [RFC 3122]. as well [RFC3122]. A PE may
optionally intercept Inverse Neighbor Solicitation and Advertisement
and learn the MAC and IPv6 interface address list of the attached CE
from the copy of the frame sent to the control plane. The PE may
optionally do MAC DA lookup in the forwarding table and send another
copy of the frame to a specific egress interface (AC or 'multicast'
PW to a remote PE) or replicate the frame onto the Send Multicast
Replication Tree (see
section 6.3).

9.5.4 Section 5.3).

8.5.4. Processing of Router Solicitations and Advertisements

Router Solicitations (RS)

RSs are multicast while Router Advertisement
(RA) RAs can be unicast or multicast Ethernet
frames. The PE could optionally intercept RS and RA frames and send
a copy to the control plane. The PE may learn the MAC address and a
list of interface addresses for the attached CE.

For unicast RA, the PE may optionally do MAC DA lookup in the
forwarding table and send the Neighbor Advertisement NA frame to a specific egress interface
(AC or 'multicast' PW to a remote PE) or replicate the frame onto the
Send Multicast Replication Tree (see
section 6.3). Section 5.3). The multicast RA
and RS Ethernet frames are replicated using the Send Multicast
Replication Tree as described in section
6.3.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

9.6 Section 5.3.

8.6. Encapsulation

The Ethernet MAC header of a unicast IP packet received from an AC is
stripped before forwarding the frame to the unicast pseudowire. PW. However, the
MAC header is retained for the following cases,
.

- when a frame is a unicast or broadcast IP packet that is
directed to one or more local AC(s).
. ACs.

- when a frame is a broadcast IP packet
.

- when a frame is an ARP packet
.

- when a frame is Neighbor/Router Solicitation/Advertisement

An IP frame received over a unicast pseudowire PW is prepended with a MAC header
before transmitting it on the appropriate AC(s). The fields in the
MAC header are filled in as follows:

- The destination MAC address is the MAC address associated with
the PW label in the FIB FIB.

- The source MAC address is the PE's own local MAC address or a
MAC address which that has been specially configured on the PE for
this use.

- The Ethernet Type field is 0x0800 if IPv4 or 0x86DD if IPv6
[RFC 2464]
[RFC2464].

- The frame may be IEEE802.1Q IEEE 802.1Q tagged based on the VLAN
information associated with the AC.

An FCS

A Frame Check Sequence (FCS) is appended to the frame.

10.0

9. Attaching to IPLS via ATM or FR Frame Relay (FR)

In addition to (i) an Ethernet port and a (ii) combination of
Ethernet port and a VLAN ID, an AC to IPLS may also be (iii) an ATM
or FR VC carrying encapsulated bridged Ethernet frames or (iv) the
combination of an ATM or FR VC Virtual Circuit (VC) and a VLAN ID.

The ATM/FR VC is just used as a way to transport Ethernet frames
between a customer site and the PE. The PE terminates the ATM/FR VC
and operates on the encapsulated Ethernet frames exactly as if those
were received on a local Ethernet interface. When a frame is
propagated from pseudowire PW to a an ATM or FR VC VC, the PE prepends the Ethernet
frame with the appropriate bridged encapsulation header as defined in [RFC 2684]
[RFC2684] and [RFC 2427] [RFC2427], respectively. Operation of an IPLS over
ATM/FR VC is exactly as described above, with the exception that the
AC is then identified via the ATM VCI/VPI or Frame Relay DLCI Data Link
Connection Identifier (DLCI) (instead of via a local Ethernet port
ID), or a combination of those with a VLAN ID.

11.0

10. VPLS vs vs. IPLS

The VPLS approach proposed in [VPLS] provides VPN services for IP as
well as other protocols. The IPLS approach described in this draft
document is similar to VPLS in many respects:

Internet Draft draft-ietf-l2vpn-ipls-16.txt

- It provides a Provider Provisioned Provider-Provisioned Virtual LAN service with
multipoint capability where a CE connected via a single
attachment circuit can reach many remote CEs

- It appears as a broadcast domain and a single subnet

- forwarding Forwarding is based on destination MAC addresses

However, unlike VPLS, IPLS is restricted to IP traffic only. By
restricting the scope of the service to the predominant type of
traffic in today's environment, IPLS eliminates the need for service
provider edge routers to implement some bridging functions such as
MAC address learning in the data path (by, instead, distributing MAC
information in the control plane). Thus Thus, this solution offers a
number of benefits:

- Facilitates It facilitates Virtual LAN services in instances where PE
devices cannot or cannot efficiently (or are specifically
configured not to) perform MAC address learning.

- Unknown Unicast frames are never flooded as would be the case
in VPLS.

- Encapsulation is more efficient (MAC (the MAC header is stripped)
for unicast IP packets while traversing the backbone network.

- PE devices are not burdened with the processing overhead
associated with traditional bridging (e.g., STP Spanning Tree
Protocol (STP) processing, etc.). Note, however, that some of
these overheads (e.g., STP processing) could optionally be turned-off
turned off with a VPLS solution in the case where it is known
that only IP devices are interconnected.

- Loops (perhaps through backdoor links) are minimized since a PE
could easily reject (via label release) a duplicate IP to MAC
address advertisement.

- Greater control over CE topology distribution.

12.0 distribution is available.

11. IP Protocols

The solution described in this document offers IPLS service for IPv4
and IPv6 traffic only. For this reason, the MAC Header header is not
carried over the unicast pseudowire. PW. It is reconstructed by the PE when
receiving a packet from a unicast pseudowire PW and the Ethertype 0x0800 or
0x86DD is used in the MAC Header header since IPv4 or IPv6 IPv6, respectively, is
assumed.

However, this solution may be extended to carry other types of
important traffic such as ISIS IS-IS , which does not use Ethernet-II,
EtherType based an
EtherType-based header. In order to permit the propagation of such
packets correctly, one may create a separate set of pseudowires, PWs, or pass
protocol information in the "control word" of a "multiprotocol"
pseudowire, PW,
or encapsulate the Ethernet MAC Header header in the
pseudowire. PW. The selection of
appropriate multiplexing/demultiplexing schemes is the subject of
future study. The current document focuses on IPLS service for IPv4
and IPv6 traffic.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

13.0 Dual Homing

12. Dual-Homing with IPLS

As stated in previous sections, IPLS prohibits the connection of a
common LAN or VLAN to more than one PE. However, the CE device
itself can connect to more than one instance of IPLS through two
separate LAN or VLAN connections to separate PEs. To the CE IP
device, these separate connections appear as connections to two IP
subnets. The failure of reachability through one subnet is then
resolved via the other subnet using IP routing protocols.

14.0

13. Proxy ARP function Function

The earlier version of this proposal used IP-PW to carry both the
broadcast/multicast and unicast IP traffic. It also discussed how PE
proxy functionality responds to the ARP requests of the local CE on
behalf of remote CE. The current version of the draft document eliminated
these functions and instead uses Ethernet PW to carry broadcast,
multicast and ARP frames to remote PEs. The motivation to use
Ethernet PW and propagate ARP frames in the current version is to
support configuration like back-to-back IPLS (similar to Inter
AS Inter-AS
option-A configurations in [RFC 4364]). [RFC4364]).

The termination and controlled propagation of ARP frames is still a
desirable option for security, DoS DoS, and other purposes. For these
reasons, we re-introduce reintroduce the ARP Proxy [PROXY-ARP] function in this
revision as an optional feature. Following The following sections describe
this option.

14.1

13.1. ARP Proxy - Responder

As a local configuration, a PE can enable the ARP Proxy responder Responder
function. In this mode, the local PE responds to ARP requests
received over the Attachment Circuit via learnt learned IP and MAC address
associations, which are advertised by the remote PEs. In addition,
the PE may utilize local policies to determine if ARP requests should
be responded based on the source of the ARP request, rate at which
the ARP requests are generated, etc. In a nutshell, when this
feature is enabled, ARP requests are not propagated to remote PE
routers that are members of the same IPLS instance.

14.2

13.2. ARP Proxy - Generator

As a local configuration, a PE can enable the ARP Proxy generator Generator
function. In this mode, the PE generates an ARP request for each IP
and MAC address associations association received from the remote PEs. The remote
CE's IP and MAC address is used as the source information in the ARP
request while the destination IP address in the request is obtained
from the local configuration (that is, user needs to configure an IP
address when this feature is enabled). The ARP request is sent on
Internet Draft draft-ietf-l2vpn-ipls-16.txt
the Attachment Circuits ACs that have ARP Proxy Generator enabled and is associated with
the given IPLS instance.

In addition, the PE may utilize local policies to determine which
IP/MAC addresses are candidate for ARP request generation.

The ARP Proxy Generator feature is required to support back-to-back
IPLS configuration when any member of the IPLS instance is using the
ARP Proxy Responder function. An example of a back-to-back IPLS is a
configuration where PE-1 (ASBR) in an IPLS cloud in one Autonomous
System (say, AS-1) is connected via an Attachment Circuit AC to another PE-2 (ASBR) in
an IPLS cloud in another Autonomous System (say, AS- 2) where each PE
appears as CE to each other. Such configuration is described in [RFC 4364]
[RFC4364] as option-A for inter-AS connectivity. The Proxy ARP responder
Responder feature prevents propagation of ARP requests to PE-1 (ASBR)
in AS-1. This necessitates that PE-1 (ASBR) in AS-1
generate generates an ARP
request on behalf of each CE connected to the IPLS instance in AS-1
as a mean to 'advertise' the reachability to IPLS cloud in AS-2

15.0 AS-2.

14. Data Center Applicability

The resurgence of interest in providing IP/MPLS based an IP/MPLS-based solution for
Data Center Networks (DCN) (DCNs) deserves another look at the IPLS
methodologies described in this document. The key requirement of a
DCN to permit VM Virtual Machine (VM) mobility within or across a DCN
necessiates extending the reachability of IP subnet over a LAN,
transparently. In addition, VMs tendency to generate frequent gratutious
gratuitous ARPs for location discovery necessiates necessitates a solution that
curbs broadcasts closest to the source.

The IPLS solution facilitates VM mobility by the PE closest to the
new location signaling the MAC address to all remote peers. In
addition, control-plane based control-plane-based MAC learning mechanisms prevent
flooding of unknown unicast across a DCN. The optional ARP proxy
mechanisms further reduces reduce ARP broadcast floods by preventing its
reach across a local PE.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

17.0

15. Security Considerations

A more comprehensive description of the security issues involved in
L2VPNs are covered in [VPN-SEC]. Most of the security issues can be
avoided through implementation of appropriate guards. The security
aspect of this solution is addressed for two planes; planes: the control
plane and data plane.

17.1 Control plane security

15.1. Control-Plane Security

The control plane control-plane security pertains to establishing the LDP
connection, pseudo-wire PW establishment and CE's IP and MAC address
distribution. The LDP connection between two trusted PEs can be
achieved by each PE verifying the incoming connection against the
configured peer's address and authenticating the LDP messages by
verifying keyed digests. The pseudo-wire PW establishments between two secure
LDP peers do not pose security issue but mis-wiring could occur due
to configuration error. Some checks, such as, proper
pseudo-wire PW type and
other pseudo-wire PW options may prevent mis-
wiring mis-wiring due to configuration errors.

The learning of the appropriate CE's IP and MAC address can be a
security issue. It is expected that the local attachment circuit to
CE be physically secured. If this is a concern, the PE must be
configured with the CE's IP and MAC address. During each ARP frame
processing, the PE must verify the received information against the
configuration before accepting. This prevents theft of service,
denial of service to a subscriber subscriber, or DoS attacks to all subscribers
by malicious use of network services.

The IPLS also provides MAC anti spoofing anti-spoofing by preventing the use of
already known MAC address. For instance, if a PE has already learned
a presence of a CE through a local connection or from another PE, and
subsequently an advertisement for the same MAC and/or IP address is
received from a different PE, the receiving PE can terminate service
to that CE (either through label release and/or removing the ARP
entry from the FIB) and raise the alarm.

The IPLS learns and distributes CE reachability through the control
plane. This provides greater control over CE topology distribution
through the application of local policies.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

17.2 Data plane security

15.2. Data-Plane Security

The data traffic between the CE and PE is not encrypted and encrypted. In an
insecure environment, it is possible that in an insecure environment, a malicious user may tap
into the CE to PE CE-to-PE connection and could conduct an active or passive
attack. An example of an active attack would be generating traffic
using the spoofed destination MAC address on the Ethernet Attachment
Circuit and a passive attack could include targeted or passive
monitoring between the CE and PE. In order to avoid such hijacking,
the local PE may verify the source MAC address of the received frame
against the MAC address of the admitted connection. The frame is
forwarded to the PW only when authenticity is verified. When
spoofing is detected, the PE must severe the connection with the
local CE, tear down the PW PW, and start over.

Each IPLS instance uses its own FIB. This prevents leaking of one
customer data into another.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

18.0

16. References

18.1

16.1. Normative References

[ARP]

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 826, STD 37, D. 2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[ARP] Plummer, "An Ethernet D., "Ethernet Address Resolution
Protocol". Protocol: Or
Converting Network Protocol Addresses to 48.bit
Ethernet Address for Transmission on Ethernet
Hardware", STD 37, RFC 826, November 1982,
<http://www.rfc-editor.org/info/rfc826>.

[PWE3-CONTROL] L. Martini et al., Martini, L., Ed., Rosen, E., El-Aawar, N., Smith, T.,
and G. Heron, "Pseudowire Setup and Maintenance
using LDP", Using
the Label Distribution Protocol (LDP)", RFC 4447. 4447,
April 2006, <http://www.rfc-editor.org/info/rfc4447>.

[PWE3-IANA] L. Martini et al,. Martini, L., "IANA Allocations for pseudo Wire Pseudowire Edge to
Edge Emulation (PWE3)", BCP 116, RFC 4446. 4446, April 2006,
<http://www.rfc-editor.org/info/rfc4446>.

[PWE3-ETH] Martini et al., Martini, L., Ed., Rosen, E., El-Aawar, N., and G.
Heron, "Encapsulation Methods for Transport of
Ethernet over MPLS Networks", RFC 4448. 4448, April 2006,
<http://www.rfc-editor.org/info/rfc4448>.

[VPLS] Lasserre et al, Lasserre, M., Ed., and V. Kompella, Ed., "Virtual
Private LAN Service (VPLS) Using LDP", Label Distribution
Protocol (LDP) Signaling", RFC 4762, January 2007.

[RFC 5036] 2007,
<http://www.rfc-editor.org/info/rfc4762>.

[RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas,
Ed., "LDP Specification", RFC 5036, October 2007.

[IEEE 802.1D] 2007,
<http://www.rfc-editor.org/info/rfc5036>.

[IEEE802.1D] ISO/IEC 10038, ANSI/IEEE Std 802.1D-1993, "MAC
Bridges".

[RFC 4861]

[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC
4861, September 2007.

[RFC 2464] 2007,
<http://www.rfc-editor.org/info/rfc4861>.

[RFC2464] Crawford, M., "Transmission of IPv6 packets Packets over
Ethernet Networks", RFC 2464, December 1998.

[RFC 3122] 1998,
<http://www.rfc-editor.org/info/rfc2464>.

[RFC3122] Conta, A., "Extensions to IPv6 Neighbor Discovery for
Inverse Discovery Specification", RFC 3122, June 2001.

[RFC 5226] 2001,
<http://www.rfc-editor.org/info/rfc3122>.

[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing
an IANA Considerations Section in RFCs", BCP 26, RFC
5226, May 2008.

Internet Draft draft-ietf-l2vpn-ipls-16.txt

18.2 2008,
<http://www.rfc-editor.org/info/rfc5226>.

16.2. Informative References

[L2VPN-FWK] Andersson, L., Ed., and E. Rosen, Ed., "Framework for
Layer 2 Virtual Private Networks (L2VPNs)", RFC 4664,
September 2006. 2006,
<http://www.rfc-editor.org/info/rfc4664>.

[PROXY-ARP] RFC 925, J. Postel, J., "Multi-LAN Address Resolution". address resolution", RFC 925,
October 1984, <http://www.rfc-editor.org/info/rfc925>.

[L2VPN-REQTS] Augustyn, W. et.al W., Ed., and Y. Serbest, Ed., "Service
Requirements for Layer 2
Provider Provisioned Provider-Provisioned Virtual
Private Networks", RFC 4665, September 2006. 2006,
<http://www.rfc-editor.org/info/rfc4665>.

[L2VPN-SIG] Rosen et al., Rosen, E., Davie, B., Radoaca, V., and W. Luo,
"Provisioning, Autodiscovery, Auto-Discovery, and
signaling Signaling in L2VPN", Layer
2 Virtual Private Networks (L2VPNs)", RFC 6074, Jan 2011.

[RFC-1112]
January 2011,
<http://www.rfc-editor.org/info/rfc6074>.

[RFC1112] Deering, S., "Host Extensions extensions for IP Multicasting", multicasting",
STD 5, RFC 1112, August, 1989.

[RFC 2684] August 1989,
<http://www.rfc-editor.org/info/rfc1112>.

[RFC2684] Grossman, et al., D. and J. Heinanen, "Multiprotocol
Encapsulation over ATM Adaptation Layer 5", RFC 2684,
September 1999.

[RFC 2427] 1999,
<http://www.rfc-editor.org/info/rfc2684>.

[RFC2427] Brown, et al., C. and A. Malis, "Multiprotocol Interconnect
over Frame Relay", STD 55, RFC 2427, September 1998.

[RFC 4364] Rosen et al., 1998,
<http://www.rfc-editor.org/info/rfc2427>.

[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private Network
Networks (VPNs)", RFC 4364, February 2006. 2006,
<http://www.rfc-editor.org/info/rfc4364>.

[VPN-SEC] Fang, L., Ed., "Security framework Framework for Provider Provider-
Provisioned Virtual Private Networks", Networks (PPVPNs)", RFC
4111, July 2005. 2005,
<http://www.rfc-editor.org/info/rfc4111>.

[ADDR-IANA] http://www.iana.org/assignments/address-family-numbers/
address-family-numbers.xhtml
Internet Draft draft-ietf-l2vpn-ipls-16.txt

16.0 IANA, "Address Family Numbers",
http://www.iana.org/assignments/address-family-
numbers/.

Acknowledgements

Authors would like to thank Alp Dibirdi from Alcatel, Xiahou from
Huawei
Huawei, and other L2VPN working group members for their valuable
comments.

1.0 Contributing Authors
Internet Draft draft-ietf-l2vpn-ipls-16.txt

Contributors

This document is the combined effort of the following individuals and
many others who have carefully reviewed this document and provided
the technical clarifications.

K. Arvind Fortress
Vach Kompella/Mathew Bocci Alcatel/Lucent
Shane Amante Apple

18.0 Author's Address

Authors' Addresses

Himanshu Shah
Ciena Corp
3939 North 1st Street, Street
San Jose, CA 95110
Email:
United States

EMail: hshah@ciena.com

Eric Rosen
Cisco Systems
300 Apollo Drive,
Chelmsford, MA 01824
Email: erosen@cisco.com

Giles Heron
Cisco Systems
Email: giheron@cisco.com
Juniper Networks, Inc.
10 Technology Park Drive
Westford, MA, 01886
United States

EMail: erosen@juniper.net

Francois Le Faucheur
Cisco Systems, Inc.
Village d'Entreprise Green Side - Batiment T3
400, Avenue de Roumanille
06410 Biot-Sophia Antipolis, Antipolis
France
Email:

EMail: flefauch@cisco.com

Giles Heron
Cisco Systems
9-11 New Square
Bedfont Lakes
Feltham
Middlesex
TW14 8HA
United Kingdom

EMail: giheron@cisco.com