LDP - can't talk to neighbor

oscarBravo · Thu Apr 29, 2010 8:58 pm

I've been setting up an MPLS network, using "loopback" interfaces and OSPF to distribute routes, then setting up LDP, and finally setting up VPLS tunnels.

This has been working perfectly so far, but I have one router ("kilbride-wt2") that won't establish an LDP connection with its neighbor ("kilbride-wt1"). kilbride-wt1 is contentedly talking to two other neighbors, but kilbride-wt2 won't talk to it.

This is the config from kilbride-wt2:

/mpls
set dynamic-label-range=16-1048575 propagate-ttl=yes
/mpls interface
add comment="" disabled=no interface=all mpls-mtu=1500
/mpls ldp
set distribute-for-default-route=no enabled=yes hop-limit=255 loop-detect=no lsr-id=10.255.112.38 \
    path-vector-limit=255 transport-address=10.255.112.38 use-explicit-null=no
/mpls ldp accept-filter
add accept=yes comment="" disabled=no neighbor=all prefix=10.255.0.0/16
add accept=no comment="" disabled=no neighbor=all prefix=0.0.0.0/0
/mpls ldp advertise-filter
add advertise=yes comment="" disabled=no neighbor=all prefix=10.255.0.0/16
add advertise=no comment="" disabled=no neighbor=all prefix=0.0.0.0/0
/mpls ldp interface
add accept-dynamic-neighbors=yes comment="" disabled=no hello-interval=5s hold-time=15s \
    interface=ether2 transport-address=0.0.0.0

kilbride-wt1 is similar, except that it has three interfaces:

/mpls
set dynamic-label-range=16-1048575 propagate-ttl=yes
/mpls interface
add comment="" disabled=no interface=all mpls-mtu=1500
/mpls ldp
set distribute-for-default-route=no enabled=yes hop-limit=255 loop-detect=no lsr-id=10.255.112.2 \
    path-vector-limit=255 transport-address=10.255.112.2 use-explicit-null=no
/mpls ldp accept-filter
add accept=yes comment="" disabled=no neighbor=all prefix=10.255.0.0/16
add accept=no comment="" disabled=no neighbor=all prefix=0.0.0.0/0
/mpls ldp advertise-filter
add advertise=yes comment="" disabled=no neighbor=all prefix=10.255.0.0/16
add advertise=no comment="" disabled=no neighbor=all prefix=0.0.0.0/0
/mpls ldp interface
add accept-dynamic-neighbors=yes comment="" disabled=no hello-interval=5s hold-time=15s \
    interface=wlan-uplink transport-address=0.0.0.0
add accept-dynamic-neighbors=yes comment="" disabled=no hello-interval=5s hold-time=15s \
    interface=ether1 transport-address=0.0.0.0
add accept-dynamic-neighbors=yes comment="" disabled=no hello-interval=5s hold-time=15s \
    interface=ether2 transport-address=0.0.0.0

Listing neighbors on kilbride-wt1:

[admin@kilbride-wt1] /mpls> ldp ne p
Flags: X - disabled, D - dynamic, O - operational, T - sending-targeted-hello, V - vpls 
 #      TRANSPORT       LOCAL-TRANSPORT PEER                       SEND-TARGETED ADDRESSES      
 0 DO   10.255.112.34   10.255.112.2    10.255.112.34:0            no            10.30.112.34   
                                                                                 10.30.150.25   
                                                                                 10.50.13.1     
                                                                                 10.99.96.1     
                                                                                 10.192.1.230   
                                                                                 10.255.112.34  
 1 D    10.255.112.38   10.255.112.2    10.255.112.38:0            no           
 2 DO   10.255.1.71     10.255.112.2    10.255.1.71:0              no            10.30.1.71     
                                                                                 10.30.112.1    
                                                                                 10.255.1.71

As you can see, kilbride-wt2 shows up, but doesn't become operational. On the other hand, on kilbride-wt2, a neighbor entry appears for about five seconds, disappears for ten seconds, but never becomes operational.

Logs show nothing, both are 433s running 4.8. Any ideas?

-headstrong- · Sun May 02, 2010 9:41 pm

try manually setting mpls interfaces to MTU of 1508

oscarBravo · Mon May 10, 2010 6:41 pm

Nope, that didn't seem to help.

Mplsguy · Tue May 11, 2010 12:15 am

I suggest you send supout.rif file, made while you experience this issue, to support@mikrotik.com.

oscarBravo · Tue May 11, 2010 12:15 pm

Done, thanks.

oscarBravo · Tue May 11, 2010 12:56 pm

...and the problem was a firewall rule that was blocking the LDP packets - a silly mistake on my part. Thanks, all.

LDP - can't talk to neighbor

LDP - can't talk to neighbor

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