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Hi,
I need to trace "MPLS-y" stuff between some routers, and wonder if
I'm missing tcpdump functionality here, namely "decode packets inside
MPLS".
I can match on "mpls" or "mpls <label>", but then I just get a hex
dump...
11:13:58.765851 MPLS (label 105, exp 0, ttl 254)
(label 24003, exp 0, [S], ttl 254)
0x0000: 0000 0000 0050 569c 338e 3cfd febd 7835 .....PV.3.<...x5
0x0010: 0800 4500 0068 1218 0000 4001 8e3b 0a1b ..E..h....@..;..
0x0020: 6302 0a1b 630a 0800 a2ea 6e4b 0738 0000 c...c.....nK.8..
0x0030: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0040: 0000 6c69 626f 7069 6e67 202d 2d20 4943 ..liboping.--.IC
0x0050: 4d50 2070 696e 6720 6c69 6272 6172 7920 MP.ping.library.
0x0060: 3c68 7474 703a 2f2f 6f63 746f 2e69 742f <http://octo.it/
0x0070: 6c69 626f 7069 6e67 2f3e liboping/>
... while tshark would nicely decode the inner headers...
MultiProtocol Label Switching Header, Label: 24002, Exp: 0, S: 1, TTL: 253
0000 0101 1101 1100 0010 .... .... .... = MPLS Label: 24002
.... .... .... .... .... 000. .... .... = MPLS Experimental Bits: 0
.... .... .... .... .... ...1 .... .... = MPLS Bottom Of Label Stack: 1
.... .... .... .... .... .... 1111 1101 = MPLS TTL: 253
Ethernet II, Src: Cisco_65:92:0f (00:c1:64:65:92:0f), Dst: IntelCor_bd:78:35
(3c:fd:fe:bd:78:35)
...
Internet Protocol Version 4, Src: 10.27.99.34, Dst: 10.27.99.2
...
Internet Control Message Protocol
Type: 0 (Echo (ping) reply)
Now, I do not want to use tshark here, because it is way too chatty -
for a quick live packet view ("1-3 lines per packet", so I can immediately
see "ah, yes, packet went out, reply is / is not coming back") without
scrolling or folding packets I like tcpdump way better...
Now, the two questions:
- is there a switch I'm missing to decode packets-in-MPLS?
(like, "packets in GRE" get decoded already)
- if not, is someone already working on it? I might just hack
it in, if not...
thanks :)
gert
--
"If was one thing all people took for granted, was conviction that if you
feed honest figures into a computer, honest figures come out. Never doubted
it myself till I met a computer with a sense of humor."
Robert A. Heinlein, The Moon is a Harsh Mistress
Gert Doering - Munich, Germany g...@greenie.muc.de
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