[c-nsp] MTU on MPLS TE Tunnels w/PA-FE-TX?

[Vinny Abello]

Rodney Dunn wrote:
> On Sun, Mar 18, 2007 at 11:08:49PM -0400, Vinny Abello wrote:
>> Nope, I think what I have wrong is is I'm not running an S train or that Cisco has not put those fixes in any mainline code yet. I checked a few routers that do have SB trains and it seems to work properly although I didn't do a complete test on them yet. I need to get some time to test more in a lab scenario.
>>
> 
> I've never seen a report of MPLS mtu set to 1508 to get 2 bytes of
> labels (1 IGP + 1 VPN) not working on those PA's. You may be having a TE
> specific problem.

Possibly... Like I said, I'm new to it, but I'm just following guides in several Cisco Press books on MPLS. Anyone feel free to make any suggestions to something obvious I'm missing. Just as an FYI, I'm currently using TDP instead of LDP due to 12.2 apparently not supporting LDP. I can switch that if this has any bearing on this problem. I just thought I'd mention it. I just want to rap my head around traffic-engineering and that's the code I'm working with currently.


Here is what I see on the tunnel interface which shows the missing 4 bytes due to what I am assuming is the label:

Interface Tunnel49024:
        IP tagging not enabled
        TSP Tunnel tagging not enabled
        Tag Frame Relay Transport tagging not enabled
        BGP tagging not enabled
        Tagging operational
        Optimum Switching Vectors:
          IP to Tag Feature Vector
          Tag Switching Feature Vector
        Fast Switching Vectors:
          IP to Tag Fast Feature Switching Vector
          Tag Switching Feature Vector
        MTU = 1496
        ^^^^^^^^^^

Tunnel configuration is basically the following:

interface Tunnel49024
 ip unnumbered Loopback0
 tunnel destination 192.168.0.24
 tunnel mode mpls traffic-eng
 tunnel mpls traffic-eng path-option 10 dynamic
 tunnel mpls traffic-eng autoroute announce


Physical interface pointing to the router with loopback of 192.168.0.24 is:

interface FastEthernet3/0
 ip address 192.168.7.101 255.255.255.252
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip router isis
 ip route-cache flow
 no ip mroute-cache
 duplex full
 mpls traffic-eng tunnels
 tag-switching mtu 1508
 tag-switching ip
 no cdp enable
 no mop enabled
 isis hello-interval 3


and the show mpls interfaces detail output for FastEthernet3/0 shows the correct MTU I set with tag-switching mtu command:


Interface FastEthernet3/0:
        IP tagging enabled
        TSP Tunnel tagging enabled
        Tag Frame Relay Transport tagging not enabled
        BGP tagging not enabled
        Tagging operational
        Optimum Switching Vectors:
          IP to Tag Feature Vector
          Tag Switching Feature Vector
        Fast Switching Vectors:
          IP to Tag Fast Feature Switching Vector
          Tag Switching Feature Vector
        MTU = 1508


As you can see, I have the tag-switching mtu set to 1508 currently. When I have autoroute announce set on the tunnel to inject the path into ISIS, I suddenly cannot ping 192.168.0.24 with packets of 1500 bytes unless I let them fragment. I can successfully ping with 1496 no problem. All these tests are performed from the headend router which is from where I'm showing all this configuration.

The actual Tunnel interface shows the following:


Tunnel49024 is up, line protocol is up
  Hardware is Tunnel
  Interface is unnumbered. Using address of Loopback0 (192.168.0.49)
  MTU 1514 bytes, BW 9 Kbit, DLY 500000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation TUNNEL, loopback not set
  Keepalive not set
  Tunnel source 192.168.0.49, destination 192.168.0.24
  Tunnel protocol/transport Label Switching, key disabled, sequencing disabled
  Checksumming of packets disabled,  fast tunneling enabled
  Last input never, output never, output hang never
  Last clearing of "show interface" counters 2d08h
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 34
  Queueing strategy: fifo
  Output queue: 0/0 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     39705 packets output, 6733402 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 output buffer failures, 0 output buffers swapped out


Again, any suggestions appreciated.

router1#sh ver | i IOS
IOS (tm) 7200 Software (C7200-JK9S-M), Version 12.2(40), RELEASE SOFTWARE (fc1)
router1#sh ver | i image
System image file is "disk0:c7200-jk9s-mz.122-40.bin"


Actual hardware:

Slot 3:
        Fast-ethernet (TX-ISL) Port adapter, 1 port
        Port adapter is analyzed
        Port adapter insertion time 5w4d ago
        EEPROM contents at hardware discovery:
        Hardware revision 1.4           Board revision B0
        Serial number     15797601      Part number    73-1688-05
        FRU Part Number:  PA-FE-TX

        Test history      0x0           RMA number     00-00-00
        EEPROM format version 1
        EEPROM contents (hex):
          0x20: 01 11 01 04 00 F1 0D 61 49 06 98 05 00 00 00 00
          0x30: 58 00 00 00 99 10 24 00 FF FF FF FF FF FF FF FF