Hi
R9 -- ATM1 -- R1
(both links are cell-mode MPLS)
I've got a weird problem in the lab where I can see LSP created across the ATM
links and I can ping R1 loopback to R9 loopback no problems, and beyond, all
labelled through LDP/OSPF. I can see the bindings are correct for this in ATM1
and the VCI/VPI looks okay too:
Rack1R9(config-vrf)#do sh mpls for 44.44.44.1
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
18 1/33 44.44.44.1/32 0 AT3/0.1 point2point
CellModeATM#sh mpls atm-ldp binding 44.44.44.1 32
Destination: 44.44.44.1/32
Headend Router ATM1/0.1 (1 hop) 1/33 Active, VCD=60
Tailend Router ATM3/0.1 1/33 Active, VCD=102
The problem is when I try to add a label to the stack. If I provision a VPN in
BGP and create loopbacks in this VPN on R1 and R9 and ping between them with no
joy.
When I come to debug I see weird label values in the FIB:
Rack1R1#sh ip cef vrf VPN_A 10.44.9.9 det
10.44.9.9/32, epoch 0
recursive via 44.44.44.9 label 31
nexthop 150.1.101.254 ATM3/0.1 label 65569
Rack1R9#sh ip cef vrf VPN_A 100.100.100.1 det
100.100.100.1/32, epoch 0
recursive via 44.44.44.1 label 31
nexthop 150.1.109.254 ATM3/0.1 label 65569
Do they actually mean anything?
Looking at the packets, you do not see the ATM VC in the label value in the
packet header (because there is no mechanism to put the values in there),
therefore you can not see if there is a problem there:
(ATM1)
19:44:06: MPLS turbo: AT3/0.1: rx: Len 112 Stack {0 0 255} {31 0 255} - ipv4
data
19:44:06: MPLS turbo: AT1/0.1: tx: Len 112 Stack {0 0 254} {31 0 255} - ipv4
data
On the other end, I see the MPLS packet come in (again with a zero'ed label)
but then I do not see the IP packet materialise in a 'debug ip packet'...
(R1)
19:45:39: MPLS turbo: AT3/0.1: rx: Len 112 Stack {0 0 254} {31 0 255} - ipv4
data
Normally in a frame-mode environment I would be able to trace the label
stacking and look at the stack change as the packets flow through the network.
I can't really do that here, other than see that the VPN label does appear to
remain. It looks like cell-mode devices do not perform PHP?
debug mpls atm-ldp X does not really produce anything helpful.
It's almost like the routers are receiving the labelled packets (w/stack) over
the ATM interfaces and the not doing anything further with them. However a
single label on the packet is okay.
Any suggestions on how to troubleshoot this further...
(Oh, and congrats Brian Bartik).
--
Dan Holme
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