RR in MPLS

Awesome material about implementing Route Reflector in MPLS network.

Functionality of RR in MPLS;

  1. It should accept all vpnv4 prefix. RR-groups can be implement so that only those vpnv4 routes filtered by RT/SOO are stored.
  2. Reflect all vpnv4 prefix without any change. Means, RR will not change/create a label. (its not going to a Next-hop for a prefix, if implemented at P-router)

So, here is the simple topology;

There is no need for RR in this simple topology. Just for the sake of playing around RR concept, R3 and R4 are act as RR (each for a specific RT/SOO using RR-group concept). Here; P-routers act as RR

R2,R5– PE routers. R0,R6- customer 1 and R1-R7– customer 2

R3(config)#ip extcommunity-list 1 permit rt 11:11
R3#show run | sec bgp
router bgp 1
no synchronization
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 1
neighbor 2.2.2.2 update-source Loopback0
neighbor 2.2.2.2 route-reflector-client
neighbor 5.5.5.5 remote-as 1
neighbor 5.5.5.5 update-source Loopback0
neighbor 5.5.5.5 route-reflector-client
no auto-summary
!
address-family vpnv4
neighbor 2.2.2.2 activate
neighbor 2.2.2.2 send-community extended
neighbor 5.5.5.5 activate
neighbor 5.5.5.5 send-community extended
bgp rr-group 1
exit-address-family
R3#
*Mar  1 00:54:01.355: %BGP-5-ADJCHANGE: neighbor 2.2.2.2 Up
R3#

Now, the neighbor is UP and expected to see all vpnv4 prefix which matches RT=11:11, but the table is empty.

R3#show ip bgp vpnv4 all

R3#

R3#show ip bgp vpnv4 all

R3#

The problem is, “neighbor x.x.x.x route-reflector-client” is applied on default ipv4 address family and not on vpnv4 address family.

Now, after reconfiguring;

R3#show ip bgp vpnv4 all
BGP table version is 8, local router ID is 3.3.3.3
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
r RIB-failure, S Stale
Origin codes: i – IGP, e – EGP, ? – incomplete

Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 1:1
*>i100.100.100.100/32
2.2.2.2                  0    100      0 2 i
R3#

HTH,

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