[c-nsp] Need help understanding mpls error message

Lobo lobotiger at gmail.com
Tue May 19 12:38:14 EDT 2009

Hmmm good point Peter.  I didn't realize that it wouldn't show up in the 
FIB.  VLAN 101 should be a trusted interface since only NMS type of 
traffic is supposed to traverse on it for this part of the network.

I'll see if there's a way to hook up a packet sniffer to that 6524 and 
see if I can figure out the MAC address from there.



Peter Rathlev wrote:
> On Tue, 2009-05-19 at 11:57 -0400, Lobo wrote:
>> I've search on Cisco's website to help understand the following message 
>> but I'm not 100% clear on how to find the network/router responsible for 
>> generating these error messages:
>> .May 19 08:39:06.235 EDT: %MPLS_PACKET-4-NOLFDSB: MPLS packet received 
>> on non MPLS enabled interface Vlan101 L3 type 0x8847 label {586 0 0 255}
> ...
>> Since it's giving multiple labels, which one should I do a "mpls 
>> forwarding-table label" command on and will that point me to the 
>> offending block?  FYI, Vlan101 is part of our NMS network and does not 
>> have LDP enabled on it.
> You probably won't be able to look it up in the FIB. As it says: You
> received a MPLS tagged frame on a non MPLS interface. This frame was
> probably not tagged with labels that your router assigned.
> What else exists on VLAN 101? Any MPLS speakers? Is VLAN 101 a "trusted"
> interface?
> With a sniffer you'd be able to see the source MAC address of the
> frames. Something like tcpdump with the "-e" flag will show you:
> 18:14:39.807669 00:19:07:73:c9:40 > 00:0b:46:5a:74:20, ethertype MPLS unicast (0x8847), length 78: MPLS (label 54, exp 0, [S], ttl 247), IP, length: 64
> Then you can look up the MAC-address in the L2 FIB.
> Regards,
> Peter

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