Understanding BGP for CLNS VPNs

BGP extensions allow BGP to carry Connectionless Network Service (CLNS) virtual private network (VPN) network layer reachability information (NLRI) between provider edge (PE) routers. Each CLNS route is encapsulated into a CLNS VPN NLRI and propagated between remote sites in a VPN.

CLNS is a Layer 3 protocol similar to IP version 4 (IPv4). CLNS uses network service access points (NSAPs) to address end systems. This allows for a seamless autonomous system (AS) based on International Organization for Standardization (ISO) NSAPs.

A single routing domain consisting of ISO NSAP devices are considered to be CLNS islands. CLNS islands are connected together by VPNs.

You can configure BGP to exchange ISO CLNS routes between PE routers connecting various CLNS islands in a VPN using multiprotocol BGP extensions. These extensions are the ISO VPN NLRIs.

Each CLNS network island is treated as a separate VPN routing and forwarding instance (VRF) instance on the PE router.

You can configure CLNS on the global level, group level, and neighbor level.

Example: Configuring BGP for CLNS VPNs

This example shows how to create a BGP group for CLNS VPNs, define the BGP peer neighbor address for the group, and define the family.

• Requirements
• Overview
• Configuration
• Verification

Requirements

Before you begin, configure the network interfaces. See the Junos OS Interfaces Library for Security Devices.

Overview

In this example, you create the BGP group called pedge-pedge, define the BGP peer neighbor address for the group as 10.255.245.215, and define the BGP family.

Configuration

CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.

Step-by-Step Procedure

1. Configure the BGP group and define the BGP peer neighbor address.
   [edit protocols bgp]user@host# set group pedge-pedge neighbor 10.255.245.213
2. Define the family.
   [edit protocols bgp]user@host# set family iso-vpn unicast
3. If you are done configuring the device, commit the configuration.
   [edit]user@host# commit

Verification

Verifying the Neighbor Status

Purpose

Display information about the BGP peer.

Action

From operational mode, run the show bgp neighbor 10.255.245.213 command. Look for iso-vpn-unicast in the output.

Peer: 10.255.245.213+179 AS 200 Local: 10.255.245.214+3770 AS 100
Type: External State: Established Flags: <ImportEval Sync>
Last State: OpenConfirm Last Event: RecvKeepAlive
Last Error: None
Options: <Multihop Preference LocalAddress HoldTime AddressFamily PeerAS
Rib-group Refresh>
Address families configured: iso-vpn-unicast
Local Address: 10.255.245.214 Holdtime: 90 Preference: 170
Number of flaps: 0
Peer ID: 10.255.245.213 Local ID: 10.255.245.214 Active Holdtime: 90
Keepalive Interval: 30 Peer index: 0
NLRI advertised by peer: iso-vpn-unicast
NLRI for this session: iso-vpn-unicast
Peer supports Refresh capability (2)
Table bgp.isovpn.0 Bit: 10000
RIB State: BGP restart is complete
RIB State: VPN restart is complete
Send state: in sync
Active prefixes: 3
Received prefixes: 3
Suppressed due to damping: 0
Advertised prefixes: 3
Table aaaa.iso.0
RIB State: BGP restart is complete
RIB State: VPN restart is complete
Send state: not advertising
Active prefixes: 3
Received prefixes: 3
Suppressed due to damping: 0
Last traffic (seconds): Received 6 Sent 5 Checked 5
Input messages: Total 1736 Updates 4 Refreshes 0 Octets 33385
Output messages: Total 1738 Updates 3 Refreshes 0 Octets 33305
Output Queue[0]: 0
Output Queue[1]: 0