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PPVPN Working Group                                     Loa Andersson
                                                          Tove Madsen
Internet-Draft                                             Utfors AB

Expiration Date: 26 Dec, 2002

                                                        27 June, 2002

                         PPVPN Terminology
            <draft-andersson-ppvpn-terminology-01.txt>


Status of this Memo

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026 [RFC2026].

Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other groups
may also distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt

The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.

For potential updates to the above required-text see:
http://www.ietf.org/ietf/1id-guidelines.txt

Summary for Sub-IP related Internet Drafts

RELATED DOCUMENTS:

This being a ppvpn terminology document, almost every document that has
been sent to the ppvpn working group is related. The reference section
include documents that define terminology that we found useful.

WHERE DOES IT FIT IN THE PICTURE OF THE SUB-IP WORK

This ID is intended for the PPVPN WG.

WHY IS IT TARGETED AT THIS WG(s)



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PPVPN deals with provider provisioned VPNs.  This document provides the
basis for a common terminology for the ppvpn working group.

JUSTIFICATION

The PPVPN WG should consider this document as a starting point for a WG
terminology that will help to create a coherent view of all the PPVPN
specifications.

Abstract

The provider provisioned VPN solutions has attracted a great deal of
interest. Memos proposing different and overlapping solution have been
discussed on the PPVPN mailing list and in the Working Group meetings.
This has lead to a development of a partly new set of concepts used to
describe the set of VPN services.  To a certain extent there are more
than one term covering the same concept and sometimes the same term
covers more than on concept. The terminology needs to be made clearer
and more intuitive. This document seeks to fill at least part of the
need.

Conventions used in this document

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].

Contents

1.  Introduction..................................................... 4

2.  PPVPN Terminology................................................ 4

3.  Provider Provisioned Virtual Private Network services............. 5
  3.1  IP-only LAN-like Service (IPLS) .............................. 5
  3.2  Layer 2 VPN (L2VPN) .......................................... 5
  3.3  Layer 3 VPN (L3VPN) .......................................... 5
  3.4  Pseudo Wire (PW) ............................................. 5
  3.5  Transparent LAN Service (TLS) ................................ 6
  3.6  Virtual LAN (VLAN) ........................................... 6
  3.7  Virtual Leased Line Service (VLLS) ........................... 6
  3.8  Virtual Private LAN Service (VPLS) ........................... 6
  3.9  Virtual Private Network (VPN) ................................ 6
  3.10  Virtual Private Switched Network (VPSN)...................... 7
  3.11  Virtual Private Wire Service (VPWS) ......................... 7

4.  Building blocks .................................................. 7
  4.1  Customer Edge device (CE) .................................... 7


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       4.1.1  Device based CE naming ................................. 8
       4.1.2  Service based CE naming ................................ 8
  4.2  Provider Edge (PE) ........................................... 9
       4.2.1  Device based PE naming ................................. 9
       4.2.2  Service based PE naming ............................... 10
       4.2.3  Distribution based PE naming .......................... 10
  4.3  Core........................................................ 11
       4.3.1  Provider router (P) ................................... 11
  4.4  Naming specific Internet drafts ............................. 11
       4.4.1  Layer 2 PE (L2PE) ..................................... 11
       4.4.2  Logical PE (LPE) ...................................... 11
       4.4.3  PE-CLE ................................................ 11
       4.4.4  PE-Core............................................... 11
       4.4.5  PE-Edge............................................... 11
       4.4.6  PE-POP ................................................ 11
       4.4.7  VPLS Edge (VE) ........................................ 12

5.  Functions....................................................... 12
  5.1  Attachment Circuit (AC) ..................................... 12
  5.2  Endpoint discovery .......................................... 12
  5.3  Flooding .................................................... 12
  5.4  MAC address learning ........................................ 12
       5.4.1  Qualified learning .................................... 13
       5.4.2  Unqualified learning .................................. 13
  5.5  Signaling................................................... 13

6.  "Boxes"......................................................... 13
  6.1  Aggregation box ............................................. 13
  6.2  Customer Premises Equipment (CPE) ........................... 13
  6.3  Multi Tenant Unit (MTU) ..................................... 14

7.  Packet Switched Network (PSN) ................................... 14
  7.1  Route Distinguisher (RD) .................................... 14
  7.2  Route Target (RT)........................................... 14
  7.3  Tunnel...................................................... 14
  7.4  Tunnel multiplexor .......................................... 15
  7.5  Virtual Channel (VC) ........................................ 15
  7.6  VC label .................................................... 15
  7.7  Inner label ................................................. 15
  7.8  VPN Routing and Forwarding (VRF) ............................ 15
  7.9  VPN Forwarding Instance (VFI) ............................... 15
  7.10  Virtual Switch Instance (VSI) .............................. 16
  7.11  Virtual Router (VR) ........................................ 16

8.  Acknowledgements ................................................ 16

9.  Authors' Contact ................................................ 16

10.  References ..................................................... 16


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1.     Introduction

There are a comparatively large number of memos being submitted to the
PPVPN and PWE3 working groups that all addresses the same problem space,
provider provisioned virtual private networking for end customer. The
memos address a wide range of services, but there is a great deal of
commonality among the proposed solutions.

This has lead to a development of a partly new set of concepts used to
describe this set of VPN services. To a certain extent there are more
than one term covering the same concept and sometimes the same term
covers more than one concept. The terminology needs to be made clearer
and more intuitive.

This document seeks to fill at least part of the need and proposes a
foundation for a unified terminology for the PPVPN working group; in
some cases the parallel concepts within the PWE3 working groups is used
as references.

2.     PPVPN Terminology

Terminology in the IETF VPN work has been and is confusing. This
document could be compared to the Stone of Rosetta. The Stone of Rosetta
was found in the town of Rosetta in northern Egypt year 1799. It was
inscribed with the same text in three different languages Greek, common
Egyptian and hieroglyphs. Thus making it possible to solve the riddle of
the hieroglyphs. In analogy with the Stone of Rosetta this document will
give you a key to your future reading and writing PPVPN texts.

The concepts and terms in this list are gathered from Internet Drafts
sent to the PPVPN mailing list and RFCs relevant to PPVPN working group.
The focus is on terminology and concepts that are specific to the PPVPN
area, but this is not strictly enforced, e.g. there are concepts and
terms within the PWE3 and MPLS areas that are closely related. We've
tried to find the earliest use of terms and concepts.

The document is structured in four major sections. Section 4 lists the
different services that has been/will be specified, Section 5 lists the
building blocks that is used to specify those services, section 6 lists
the functions needed in those services and section 7 list some typical
devices used in customer and provider networks.



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3.     Provider Provisioned Virtual Private Network services

In this section we define the terminology that relates the set of
services to solutions specified by the PPVPN working group. The concept
"pseudo wire" that belongs to the PWE3 working group is included for
reference purposes. For requirements in provider provisioned VPNs see
[PPVPN-req].

In this section all abbreviations are listed in alphabetic order.

3.1 IP-only LAN-like Service (IPLS)

An IPLS is very like a VPLS (see 4.8), except that:

  -  it is assumed that the CE devices (see 5.1) are hosts or routers,
       not switches

  -  it is assumed that the service will only need to carry IP packets,
       and supporting packets such as ICMP and ARP; otherwise layer 2
       packets which do not contain IP are not supported.

While this service is a functional subset of the VPLS service, it is
considered separately because it may be possible to provide it using
different mechanisms, which may allow it to run on certain hardware
platforms that cannot support the full VPLS functionality. [PPVPN -L2-
frmwrk]

3.2 Layer 2 VPN (L2VPN)

Three types of L2VPNs are described in this document, Virtual Private
Wire Service (VPWS) (section  3.3), VPLS Virtual Private LAN Service
(VPLS)(section 4.8), and IP-only LAN-like Service (IPLS).

3.3 Layer 3 VPN (L3VPN)

An L3VPN is a solution, that interconnects several sets of hosts and
routers and allows them to communicate based on L3 addresses, see
[PPVPN-frmwrk].

3.4 Pseudo Wire (PW)

The PWE3 working group within IETF specifies the pseudo wire technology.
A pseudo wire is an emulated point-to-point connectivity over a packet
switched network that gives the possibility to interconnect two nodes
with any L2 technology. The PW shares some of the building blocks and
architecture constructs with the point to multipoint solutions, e.g. PE
(see 5.2) and CE (see 5.1). An early solution for PWs is described in


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[martini-tran]. Encapsulation formats readily used in VPWS, VPLS and PWs
are described in [martini-encap]. Requirements for PWs are found in
[PWE3-req] and [PWE3-frmwrk] present an architectural framework for PWs.

3.5 Transparent LAN Service (TLS)

TLS was the first name used to describe the VPLS service, it was used
e.g. in the now dated draft-lasserre-tls-mpls-00.txt. It has been
replaced by VPLS, which is now the current term.

3.6  Virtual LAN (VLAN)

A VLAN is a way of separating traffic on a LAN, e.g. between different
departments within a company. This acronym is not defined by PPVPN
working group, but is defined by IEEE 802.1Q. The VLANID is used to mark
an Ethernet frame with a tag to create user groups on a LAN.

3.7 Virtual Leased Line Service (VLLS)

The VLLS has been replaced by VPWS. It was used in now dated draft-
ppvpn-metrics.00.txt.

3.8 Virtual Private LAN Service (VPLS)

A VPLS is a provider service that emulates the full functionality of a
traditional Local Area Network. A VPLS makes it possible to interconnect
several LAN segments over a packet switched network (PSN) and makes the
remote LAN segments behave as one single LAN. For early work on defining
a solution and protocol for a VPLS see [VPLS-req], [Lasserre-vkompella],
and [Kompella-VPLS ].

In a VPLS the provider network emulates a learning bridge and forwarding
decisions are taken based on MAC addresses or MAC addresses and VLAN
tag.

3.9 Virtual Private Network (VPN)

VPN is a generic term that covers the use of a public or private
networks to create groups of users that is separated from other network
users and may communicate among them as if they were on a private
network. The level of separation is possible to enhance e.g. by end-to-
end encryption, this is however outside the scope of PPVPN working group
charter. This VPN definition is from [RFC2764].

In the [L3VPN-frmwrk] the term VPN is used to refer to a specific set of
sites as either an intranet or an extranet that have been configured to



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allow communication. Note that a site is a member of at least one VPN,
and may be a member of many VPNs.

In this document "VPN" is also used as a generic name for all services
listed in section 3.

3.10  Virtual Private Switched Network (VPSN)

A VPSN is replaced by VPLS. The VPSN abbreviation was used e.g. in the
now dated draft-vkompella-ppvpn-vpsn.reqmts-00.txt.

3.11  Virtual Private Wire Service (VPWS)

A Virtual Private Wire Service (VPWS) is a point-to-point circuit (link)
connecting two Customer Edge devices. The CE in the customer network is
connected to a PE in the provider network via an Attachment Circuit (see
6.1); the Attachment Circuit is either a physical or a logical circuit.

The PE's in the core network is connected via a PW.

The CE devices can be routers, bridges, switches or hosts. In some
implementations a set of VPWSs is used to create a multi-site L2VPN
network. An example of a VPWS solution is described in [L2VPN].

A VPWS differs from a VPLS (section4.8) in that the VPLS is point to
multipoint, while the VPWS is point to point. See [L2-frmwrk].

4.     Building blocks

Starting with specifications of L3VPNs, e.g. the 2547 specification
[RFC2547] and  [RFC2547bis] and Virtual Routers [PPVPN-VR], a way of
describing the building blocks and allocation of functions in VPN
solutions was developed. The building blocks are often in day-to-day
talk treated as if it were physical boxes, common for all services.
However, for different reasons this is to over-simplify. Any of the
building blocks could be implemented across more than one physical box.
How common the use of such implementations will be is beyond the scope
of this document.

4.1 Customer Edge device (CE)

A CE is the name of the device with the functionality needed on the
customer premises to access the services specified by the PPVPN working
group.




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There are two different aspects that need to be considered in naming CE
devices. One could start with the type of device that is used to
implement the CE (see section 4.1.1). It is also possible to use the
service the CE provides and with the result will be a set of "prefixed
CEs", (see section 4.1.2).

It is common practice to use "CE" to indicate any of these boxes, since
it is very often unambiguous in the specific context.

4.1.1 Device based CE naming


4.1.1.1 Customer Edge Router (CE-R)

A CE-R is a router in the customer network interfacing the provider
network. There are many reasons to use a router in the customer network,
e.g. in an L3VPN using private IP addressing this is the router that is
able to do forwarding based on the private addresses. Another reason to
require the use of a CE-R on the customer side is that one want to limit
the number on MAC-addresses that needs to be learnt in the provider
network.

A CE-R could be used to access both L2 and L3 services.

4.1.1.2 Customer Edge Switch (CE-S)

A CE-S is a service aware L2 switch in the customer network interfacing
the provider network. In a VPWS or a VPLS it is not strictly necessary
to use a router in the customer network, a layer 2 switch might very
well do the job.

4.1.2 Service based CE naming

The list below is just examples and it will be extended as the number of
services increases.

4.1.2.1 L3VPN-CE

An L3VPN-CE is the device or set of devices on the customer premises
that attaches to a provider provisioned L3VPN, e.g. a 2547bis
implementation.







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4.1.2.2 VPLS-CE

A VPLS-CE is the device or set of devices on the customer premises that
attaches to a provider provisioned VPLS.

4.1.2.3 VPWS-CE

A VPWS-CE is the device or set of devices on the customer premises that
attaches to a provider provisioned VPWS.

4.2 Provider Edge (PE)

A PE is the name of the device or set of devices at the edge of the
provider network with the functionality that is needed to interface the
customer. PE, without further qualifications, is very often used for
naming the devices since it is made unambiguous by the context.

In naming PEs there are three aspects that we need to consider, the
service they support, whether the functionality needed for service is
distributed across more than one device and the type of device they are
build on.

4.2.1 Device based PE naming

Both routers and switches may be used to implement PEs, however the
scaling properties will be radically different depending which type of
equipment that is chosen.

4.2.1.1 Provider Edge Router (PE-R)

A PE-R is a L3 device that participates in the PSN (see section 7)
routing and forwards packets based on the routing information.

4.2.1.2 Provider Edge Switch (PE-S)

A PE-S is a L2 device that participates in e.g. a switched Ethernet
taking forwarding decision packets based on L2 address information.









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4.2.2 Service based PE naming


4.2.2.1 L3VPN-PE

An L3VPN-PE is a device or set of devices at the edge of the provider
network interfacing the customer network, with the functionality needed
for an L3VPN.


4.2.2.2 VPWS-PE

A VPWS-PE is a device or set of devices at the edge of the provider
network interfacing the customer network, with the functionality needed
for a VPWS.

4.2.2.3 VPLS-PE

A VPLS-PE is a device or set of devices at the edge of the provider
network interfacing the customer network, with the functionality needed
for a VPLS.

4.2.3 Distribution based PE naming

For scaling reasons it is in the VPLS/VPWS cases sometimes desired to
distribute the functions in the VPLS/VPWS-PE across more than one
device, e.g. is it feasible to allocate MAC address learning on a
comparatively small and in-expensive device close to the customer site,
while participation in the PSN signalling and set up of PE to PE tunnels
are done by routers closer to the network core.

When distributing functionality across devices a protocol is needed to
exchange information between the Network facing PE (N-PE) (see section
4.2.3.1) and the User facing PE (U-PE) (see section 4.2.3.2).

4.2.3.1 Network facing PE (N-PE)

The N-PE is the device to which the signalling and control functions are
allocated when a VPLS-PE is distributed across more than one box.


4.2.3.2 User facing PE (U-PE)

The U-PE is the device to which the functions needed to take forwarding
or switching decision at the ingress of the provider network.



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4.3 Core

4.3.1 Provider router (P)

The P is defined as a router in the core network that does not have
interfaces directly towards a customer. Hence a P router does not need
to keep VPN state and is VPN un-aware.

4.4 Naming specific Internet drafts

4.4.1 Layer 2 PE (L2PE)

L2PE is the joint name of the devices in the provider network that
implement L2 functions needed for a VPLS or a VPWS.

4.4.2 Logical PE (LPE)

The term Logical PE (LPE) originates from [LPE] and is used to describe
a set of devices used in a provider network to implement a VPLS. In a
LPE VPLS functions are distributed across small devices (PE-Edges/U-PE)
and devices attached to a network core (PE-Core/N-PE). In an LPE
solution the PE-edge and PE-Core can be interconnected by a switched
Ethernet transport network(s) or uplinks. The LPE will appear to the
core network as a single PE. In this document the devices that
constitutes the LPE is called N-PE and U-PE.

4.4.3 PE-CLE

Name for the U-PE in [sajassi ].

4.4.4 PE-Core

See use in section 4.4.2.

4.4.5 PE-Edge

See use in section 4.4.2.

4.4.6 PE-POP

Name for the N-PE in [sajassi ].






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4.4.7 VPLS Edge (VE)

The term VE originates from [DTLS] and is used to describe the device
used by a provider network to hand off a VPLS to a customer. In this
document the VE is called a VPLS-PE.

This name has dated.

5.     Functions

In this section we have grouped a number of concepts and terms that has
to be performed to make the VPN services work.

5.1 Attachment Circuit (AC)

In a Layer 2 VPN the CE is attached to PE via an Attachment Circuit
(AC). The AC may be a physical or logical link.

5.2 Endpoint discovery
Endpoint discovery is the process by which the devices that are
aware of a specific VPN service will find all customer facing
ports that belong to the same service.


The requirements on endpoint discovery and signalling are discussed in
[VPN-discov] and [PPVPN-req].

5.3 Flooding

Flooding is a function related to L2 and L3 services; when a PE receives
a frame with an unknown destination MAC-address, that frame is send out
over (flooded) every other interface.

5.4 MAC address learning

MAC address learning is a function related to L2 services; when PE
receives a frame with an unknown source MAC-address the relationship
between that MAC-address and interface is learnt for future forwarding
purposes. In a layer 2 VPN solution from the PPVPN WG, this function is
allocated to the VPLS-PE.







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5.4.1 Qualified learning

In qualified learning, the learning decisions at the U -PE are based on
the customer Ethernet frame's MAC address and VLAN tag, if a VLAN tag
exists. If no VLAN tag exists, the default VLAN is assumed.

5.4.2 Unqualified learning

In unqualified learning, learning is based on a customer Ethernet
frame's MAC address only.

5.5 Signaling

Signalling is the process by which the PEs that have VPNs behind them
exchange information to set up PWs, PSN tunnels and tunnel multiplexors.
This process might be automated through a protocol or the done by manual
configuration. Different protocols may be used to establish the PSN
tunnels and exchange the tunnel multiplexors.

6.     "Boxes"

We list a set of boxes that will typically be used in an environment
that supports different kinds of VPN services. We have chosen to include
some names of boxes that originate outside the protocol specifying
organisations.

6.1 Aggregation box

The aggregation box is typically an L2 switch that is service un-aware
and is used only to aggregate traffic to more function rich points in
the network.

6.2 Customer Premises Equipment (CPE)

The CPE equipment is the box that a provider places with the customer.
It serves two purposes ยก giving the customer ports to plug in to and
making it possible for a provider to monitor the connectivity to the
customer site. The CPE is typically a low cost box with limited
functionality and in most cases not aware of the VPN services offered by
the provider network.

The CPE equipment is not necessarily the equipment to which the CE
functions are allocated, but is part of the provider network and used
for monitoring purposes.



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The CPE name is used primarily in network operation and deployment
contexts, and should not be used in protocol specifications.



6.3 Multi Tenant Unit (MTU)

An MTU [DTLS] is typically an L2 switch placed by a service provider in
a building where customers of that service provider are located.

The MTU device name is used primarily in network operation and
deployment contexts, and should not be used in protocol specifications,
as it is also a used abbreviation for Maximum Transmit Units.

7.     Packet Switched Network (PSN)

A PSN is the network through which the tunnels supporting the VPN
services are set up.

7.1 Route Distinguisher (RD)

A Route Distinguisher [RFC2547bis] is an 8-byte value that together with
a 4 byte IPv4 address identifies a VPN-Ipv4 address family. If two VPNs
use the same Ipv4 address prefix, the PEs translates these into unique
VPN-IPv4 address prefixes. This ensures that if the same address is used
in two different VPNs, it is possible to install two completely
different routes to that address, one for each VPN.

7.2 Route Target (RT)

A Route Target attribute [RFC2547bis] can be thought of as identifying a
set of sites, or more precisely a set of VRFs (see section8.8).
Associating a particular Route Target with a route, allows that route to
be placed in all VRFs that are used for routing traffic received from
the corresponding sites.

A Route Target attribute is also a BGP extended community used in
[RFC2547], and [BGPVPN-auto]. A Route Target community is used to
constrain VPN information distribution to the set of VRFs. A route-
target can be perceived as identifying a set of sites, or more precisely
a set of VRFs.

7.3 Tunnel

A tunnel is connectivity through a PSN that is used to send traffic
across the network from one PE to another. The tunnel provides a


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mechanism to transport packets from one PE to another, separation of one
customer's traffic from another customer's traffic is done based on
tunnel multiplexors (see section 8.4). How the tunnel is established
depends on the tunnelling mechanisms provided by the PSN, i.e. the
tunnel could be based on e.g. the IP-header, an MPLS label, the L2TP
Session ID, or on the GRE Key field.

7.4 Tunnel multiplexor

A tunnel multiplexor is an entity that is sent with the packets
traversing the tunnel to make possible to decide to which instance of a
service a packet belongs and from which sender it was received. In
[L2VPN] the tunnel multiplexor is formatted as an MPLS label.

7.5 Virtual Channel (VC)

A VC is transported within a tunnel and identified by its tunnel
multiplexor. A virtual channel is identified by a VCI (Virtual Channel
Identifier). In the PPVPN context a VCI is a VC label or tunnel
multiplexor and in the Martini case it is equal to the VCID.

7.6 VC label

In an MPLS enabled IP network a VC label is an MPLS label, used to
identify traffic within a tunnel that belongs to a particular VPN, i.e.
the VC label is the tunnel multiplexor in networks that uses MPLS
labels.

7.7 Inner label

"Inner label" is another name for VC label (see section 8.6).

7.8 VPN Routing and Forwarding (VRF)

In networks running 2547 VPN's [RFC2547], PE routers maintain VRF's. A VRF is a
per-site forwarding table. Every site to which the PE router is attached is
associated with one of these tables.  A particular packet's IP destination
address is looked up in a particular VRF only if that packet has arrived
directly from a site, which is associated with that table.

7.9 VPN Forwarding Instance (VFI)

VPN Forwarding Instance (VFI) is a logical entity that resides in a PE
that includes the router information base and forwarding information
base for a VPN instance [PPVPN-frmwrk].




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7.10  Virtual Switch Instance (VSI)

In a layer 2 context a VSI is a virtual switching instance that serves
one single VPLS [L2-frmwrk].  A VSI performs standard LAN (i.e.,
Ethernet) bridging functions. Forwarding done by a VSI is based on MAC
addresses and VLAN tags, and possibly other relevant information on a
per VPLS basis. The VSI is allocated to VPLS-PE or in the distributed
case to the U-PE.

7.11  Virtual Router (VR)

A Virtual Router (VR) is software and hardware based emulation of a
physical router. Virtual routers have independent IP routing and
forwarding tables and they are isolated from each other, see [PPVPN-VR].

8.       Acknowledgements

Much of the content in this document is based on discussion in the PPVPN
design teams for "auto discovery" and "l2vpn".

9.       Authors' Contact

       Loa Andersson
       Utfors AB
       Rasundavagen 12, PO Box 525
       SE-169 29 Solna, Sweden
       phone: +46 8 5270 5038
       loa.andersson@utfors.se

       Tove Madsen
       Utfors AB
       Rasundavagen 12, PO Box 525
       SE-169 29 Solna Sweden
       phone: +46 8 5270 5040
       tove.madsen@utfors.se

10.  References

[BGPVPN-auto]
            Ould-Brahim, H. et.al. "Using BGP as an auto-discovery
            mechanism for network-based VPNs", draft-ietf-ppvpn-bgpvpn-
            auto-02.txt, Work in progress, Internet Draft, February 2002




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[DTLS]  Kompella, K., et.al. "draft-kompella-ppvpn-dtls-01.txt",
        Work in progress, Internet Draft, November 2001

[kompella-VPLS]
        Kompella, K. "Virtual Private LAN Service", draft -kompella-
        ppvpn-vpls-01.txt, Work in Progress, Internet Draft, March
        2002

[L2-frmwrk]
        Andersson, Loa "PPVPN L2 Framework", draft-andersson-ppvpn-
        l2-framework-01.txt, Work in Progress, Internet Draft, June
        2002

[L2VPN]  Kompella, K., et.al. "MPLS-based Layer 2 VPNs" draft-
        kompella-ppvpn-l2vpn-02.txt, Work in Progress, June 2002

[L3VPN-frmwrk]
        Callon, R., et.al. "A Framework for Layer 3 Provider
        Provisioned Virtual Private Networks", draft-ietf -ppvpn-
        framework-05.txt, Work in Progress, Internet Draft, April
        2002

[lasserre-vkompella]
        Kompella, V., Lasserre, M., et.al. "Transparent VLAN
        Services over MPLS" draft-lassere-vkompella-ppvpn -vpls-
        01.txt, Work in progress, Mar 2002

[LPE]   Ould-Brahim, H., et.al. "VPLS/LPE L2VPNs: Virtual Private
        LAN Services using Logical PE Architecture", draft-
        ouldbrahim-l2vpn-lpe-02.txt, Work in Progress, Internet
        Draft, March  2002

[martini-encap]
        Martini, L., et.al. "draft-martini-l2circuit-encap-mpls-
        04.txt", Work in Progress, Internet Draft, November 2001

[martini-tran]
        Martini, L., et.al. "draft-martini-l2circuit-trans-mpls-
        09.txt", Work in progress, Internet Draft, April 2002

[PPVPN-L2-frmwrk]
        Andersson, Loa "PPVPN L2 Framework", draft-andersson-ppvpn-
        l2-framework-nn.txt, Work in progress, Internet Draft, June
        2002




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[PPVPN-frmwrk]
        Callon, R., et.al. "A Framework for Provider Provisioned
        Virtual Private Networks", draft-ietf-ppvpn-framework-
        05.txt, Work in Progress, Internet Draft, April 2002

[PPVPN-req]
        Carugi, M., et.al. "Service requirements for Provider
        Provisioned Virtual Private Networks", draft-ietf -ppvpn-
        requirements-04.txt, Work in Progress, Internet Draft, April
        2002

[PPVPN-VR]
        Ould-Brahim, H., et.al. "Network-based IP VPN using Virtual
        Routers", draft-ietf-ppvpn-vpn-vr-02.txt, Work in Progress,
        Internet Draft, February 2002

[PWE3-frmwrk]
        Prayson, P., et.al. "Framework for Pseudo Wire Emulation
        Edge-to-Edge (PWE3)", draft-ietf-pwe3-framework-01.txt, Work
        in Progress, Internet Draft, June 2002

[PWE3-req]
        XiPeng Xiao, et.al. "Requirements for Pseudo-Wire Emulation
        Edge-to-Edge (PWE3)", draft-ietf-pwe3-requirements-02.txt

[RFC2547]
        Rosen, E., et.al. "BGP/MPLS VPNs", rfc2547, March 1999

[RFC2547bis]
        Rosen, E., et.al. "BGP/MPLS VPNs", draft-ietf-ppvpn-
        rfc2547bis-01.txt, Work in Progress, Internet Draft, January
        2002

[RFC2764]
        Gleeson, B., et.al. "A Framework for IP Based Virtual
        Private Networks", rfc2764, February 2000

[sajassi]
        Sajassi, A. "VPLS Architectures", draft-sajassi-vpls-
        architectures -00.txt, Work in Progress, Internet Draft,
        February 2002

[VPLS-req]
        Waldemar Augustyn, et.al. "Requirements for Virtual Private
        LAN Services (VPLS)", draft-ietf-ppvpn-vpls-requirements-
        00.txt, Work in Progress, Internet Draft, April 2002. This
        draft replaces draft-augustyn-vpls-requirements-02.txt, Work
        in Progress, Internet Draft, February 2002.



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[VPN-discov]
        Squire, M. "VPN Discovery Discussions and Options" draft-
        squire-ppvpn-vpn-discovery-reqts-00.txt, Work in Progress,
        Nov 2001

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