LDP neighbor relationship fails

[Ulrich Hansen]

Hi,

I have LDP peering between my PE and P nodes in a datacenter enviroment.

One of the PE nodes reports the following:

2011 Aug 29 09:40:20.781 DC1SD01 %LCON-3-DUP_ADDR_RCVD:    Duplicate Address 184549342 advertised by peer 10.255.255.254:0 is already bound to 10.255.255.253:0

2011 Aug 29 09:40:20.781 DC1SD01 %LCON-3-LDPID:    peer 10.255.255.254:0, LDP Id/Addr mapping problem (rcvd LDP address message, bind failed)

I'm somewhat familiar with this errormsg, but the highlighted "address" makes little sense to me. If it's a label value, I'm unable to locate it on either of the two P-nodes nor the PE-node. Apparently this causes the LDP relationship to fail and subsequently re-establishes.

Can anyone shed some light on this?

Thanks

/Ulrich

[Ivan Krimmel]

Hallo Ulrich,

I would recommend to find out why 10.255.255.222 comes from 10.255.255.254, as it is already known by this peer from 10.255.255.253

HTH,

Ivan.

[Ulrich Hansen]

Hi Ivan,

Thanks for replying.

10.255.255.222 is our mcast RP-address and it is identically configured on all four P-nodes. The thing is, that this P/PE node relationship are the only ones reporting this problem. All other P/PE node relationsship do not experience this problem.

Failed to recognize that the value was an IP expressed in decimal.

/Ulrich

[Ivan Krimmel]

Ulrich,

I guess the problem appears only on the node, where this IP is being learned twice with different labels.

[Luc De Ghein]

Hi,

The duplicate address is a bound IP address to the router, i.e. an interface IP address. If this address is not used for unicast forwarding (and MPLS), then there is no issue. It looks like this is the case because you mentioned that this

is used for multicast anycast.

Thanks,

Luc

[Peter Paluch]

Hello Ulrich,

In addition to other friends' answers here, the "strange" IP address in the logging message output corresponds to the IP address 10.255.255.222:

peterp@handel:~$ ping 184549342
PING 184549342 (10.255.255.222) 56(84) bytes of data.
^C
--- 184549342 ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 999ms

It is simply given in a linear format instead of being split into 4 octets. Perhaps this may help you identify the offending IP or Router ID.

Best regards,

Peter

[Luc De Ghein]

The LDP peers are 10.255.255.254:0 and 10.255.255.253:0.

Thanks,

Luc

[Peter Paluch]

Luc,

I do not object to that. I am only saying that the IP address displayed in the error message that Ulrich asked about in the first place corresponds to dotted-decimal format 10.255.255.222. Where that IP address came from is another issue - I assume that Ulrich will be able to identify that device.

Best regards,

Peter