Dynamic PMSI for MPBGP MVPN

Dynamic PMSI for MPBGP MVPN Summated by: Boris Zhang, TELUS Inc.

Purpose

When RSVP P2MP LSP is used as provider tunnel (PMSI) to transport multicast traffic for layer3 VPN, Junos allows you to configure dynamic leaf discovery. P2MP LSP is automatically created towards originating router loopback address derived from PMSI AD routes. However, in some case there are multiple loopback addresses on originating router and you are requested to create LSP towards specific one address over another for routing isolation.

Solution

Junos supports to specify address as primary and explicitly configure router-id, combined with specific behaviour of LDP and MPBGP which allows you to manipulate LDP label binding and AD routes to solve the problem.

Step 1: Create loopback0 interface with two addresses. 1.1.1.1 is specified as primary- address which is requested to be destination address as leaf node; 1.1.1.10 is targeted to be router-id for all protocols. interfaces { loopback0 { unit 0 { family inet { address 1.1.1.1/32 { primary; } address 1.1.1.10/32; } } } }

Step 2: 1.1.1.10 is configured as router-id routing-options { router-id 1.1.1.10; }

Step 3: Enable LDP on loopback0 interface. Without egress export policy, LDP only generate FEC for loopback address same as router-id. Consequently, there is only 1.1.1.10 being advertised out with label but not 1.1.1.1. protocols {

1 ldp { interface lo0.0; } }

Step 4: Create P2MP LSP template and apply to MVPN provider-tunnel. It’s a default behaviour for MVPN using primary-address as originating router loopback address to build AD routes protocols { mpls { label-switched-path mvpn1_template { template; p2mp; } } } routing-instances { mvpn1 { provider-tunnel { rsvp-te { label-switched-path-template { mvpn1_template; } } } } }

With above 4 steps, you end up with a desired result. The output from remote PE are exactly as we expected.

 There is no LDP route for 1.1.1.1  Originating router loopback inside AD route is 1.1.1.1  P2MP LSP is established correctly to 1.1.1.1  1.1.1.10 is advertised through LDP and used as router-id abc@PE2> show route protocol ldp | match 1.1.1 1.1.1.10/32 #[LDP/9] 18:26:54, metric 30000 abc@PE2> show route table mvpn1.mvpn.0 mvpn1.mvpn.0: 12 destinations, 22 routes (12 active, 4 holddown, 0 hidden) + = Active Route, - = Last Active, * = Both

2 1:1.1.1.10:100:1.1.1.1/240 *[BGP/170] 05:30:51, localpref 100, from 1.1.1.10 AS path: I > to 10.1.35.2 via ge-5/1/2.35, Push 431986 abc@PE2> show mpls lsp Ingress LSP: 85 sessions To From State Rt P ActivePath LSPname 1.1.1.1 1.1.1.2 Up 0 * 1.1.1.1:1.1.1.2:100:mvpn:mvpn1