Routing

I understand the concept of family route-target but when I issue the command family route-target under my internal BGP group on all of my routers (P and PE), BGP fails to establish to the routers not running inet-vpn routing-instances (P and some PE routers). Only when I issue family route-target under protocols bgp do things work correctly.  Is that suppose to happen?

My routers are on JunOS 9.6.R4.4.

Hi,

The NLRI families under "group" configurations has higher precedence over the one under "protocol bgp".

When you have configured "family route-target" under "protocol bgp", it wouldn't had any effect.

You can confirm

show bgp neighbor <peer_address. | grep "NLRI for this session"

For BGP peers to come up, the NLRI should match on both sides otherwise you will see this error in syslog

bgp_process_caps: mismatch NLRI with 3.3.3.3 (Internal AS 100): peer: <l2vpn route-target inet-flow>(12352) us: <l2vpn inet-flow>(8256)

Regards

Surya Prakash

BGP establishes but RED.inet.0 and bgp.rtarget.0 not populated using this configuration:

protocols bgp family inet unicast

protocols bgp family inet-vpn unicast

protocols bgp group int type internal

protocols bgp group int family route-target  <--- does this override the other families I have configured under bgp?

protocols bgp group int neighbor <IP>

BGP establishes, RED.inet.0, and bgp.rtarget.0 populated using this configuration:

protocols bgp group int type internal

protocols bgp group int family inet unicast

protocols bgp group int family inet-vpn unicast

protocols bgp group int family route-target

protocols bgp group int neighbor <IP address>

your bgp neighbor config with only family route-target (in first section). the FAMILY don't inherited by groups, if you config its under protocol bgp.

Hi,

When you don't have any family configured under group level, BGP uses the families configured in next level which in your case is under"protocols bgp", for NLRI capabilities. Otherwise families configured under BGP group would take precedence.

In your first set of configs, only "family route-target" NLRI would be advertised and in the second case all families would be advertised. Hence you see respective tables being populated for second set of configs.

Let see with an example with PE1 and PE2 as BGP peers:

<<< PE1 is configured for families inet-vpn and l2vpn, both under group level >>>>>

suryak@PE1# show protocols bgp
group int {
    type internal;
    local-address 1.1.1.1;
    family inet-vpn {
        unicast;
    }
    family l2vpn {
        signaling;
    }
    neighbor 3.3.3.3;
}

suryak@PE1# run show bgp summary
Groups: 1 Peers: 1 Down peers: 0
Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending
inetflow.0             0          0          0          0          0          0
bgp.l2vpn.0            1          1          0          0          0          0
bgp.l3vpn.0            0          0          0          0          0          0
Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State|#Active/Received/Accepted/Damped...
3.3.3.3                 100          6          6       0       4        1:08 Establ
  bgp.l2vpn.0: 1/1/1/0
  VPNA.l2vpn.0: 1/1/1/0



<<<<<< PE2 is configured with family inet-vpn under protocol level and family l2vpn under group level >>>>>

suryak@PE2# show protocols bgp
family inet-vpn {
    unicast;
}
group int {
    type internal;
    local-address 3.3.3.3;
    family l2vpn {
        signaling;
    }
    neighbor 1.1.1.1;
}

suryak@PE2# run show bgp summary
Groups: 1 Peers: 1 Down peers: 0
Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending
bgp.l2vpn.0            1          1          0          0          0          0
bgp.l3vpn.0            0          0          0          0          0          0
Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State|#Active/Received/Accepted/Damped...
1.1.1.1                 100          6          7       0       0        1:23 Establ
  bgp.l2vpn.0: 1/1/1/0
  VPNA.l2vpn.0: 1/1/1/0




<<< AS YOU SEE PE2 and PE1 has populated tables only which corresponds to l2vpn >>>>
<<< and if we check on PE1, the NLRI advertised by PE2 would be only l2vpn which was under group level >>>>


suryak@PE1# run show bgp neighbor | grep "NLRI advertised by peer"
  NLRI advertised by peer: l2vpn



<<<< Now if I configure inet-vpn family under group level in PE2 as well, then >>>>>


suryak@PE2# show protocols bgp
family inet-vpn {
    unicast;
}
group int {
    type internal;
    local-address 3.3.3.3;
    family inet-vpn {
        unicast;
    }
    family l2vpn {
        signaling;
    }
    neighbor 1.1.1.1;
}

suryak@PE2# run show bgp summary
Groups: 1 Peers: 1 Down peers: 0
Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending
bgp.l2vpn.0            1          1          0          0          0          0
bgp.l3vpn.0            0          0          0          0          0          0
Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State|#Active/Received/Accepted/Damped...
1.1.1.1                 100          3          4       0       0           7 Establ
  bgp.l2vpn.0: 1/1/1/0
  VPNA.l2vpn.0: 1/1/1/0
  bgp.l3vpn.0: 0/0/0/0


<<< We observe correspondong l3vpn table as well along with l2vpn table >>>
<<< Checking on PE1 for NLRI advertised by PE2 >>>

suryak@PE1# run show bgp neighbor | grep "NLRI advertised by peer"
  NLRI advertised by peer: inet-vpn-unicast l2vpn



Hope this helps

Regards

Surya Prakash

Thanks Surya!!  That was a good example!

use traceoption for bgp and you find your problem