MTU not considered when xconnect switches to backup peer

[gule1]

Hi !

I have an issue on CISCO7609-S Version 12.2(33)SRC1.

Given this simple config :

int Te9/2.4000

encaps dot1q 4000

xconnect 10.10.10.10 10104000 encaps mpls

backup peer 10.10.10.11 10114000

backup delay 10 30

mtu 9100

When UP with primary peer, MTU is 9100 but when it switches to backup peer, MTU returns to default value 9216.

Did someone already notice that ? Is there any workaround ?

Thanks.

[balaji.bandi]

CISCO7609-S Version 12.2(33)SRC1.

may be EOL decade back  coming to your issue, what is the main interface MTU configured , i dont remember you can change sub-interface MTU ?

[gule1]

main interface MTU is 9216. Actually, here we modify MTU in the "xconnect" context (for compliance with remote peer).

It works with the primary peer, not with the backup peer..

So you guess it's an IOS software issue ? I performed research but found nothing about this..

As you can see with a "sho mpls l2transport vc int Te9/2.4000 detail", local MTU is 9216 in the backup section.

Local interface: Te9/2.4000 up, line protocol up, Eth VLAN 4000 up
  MPLS VC type is Eth VLAN, interworking type is Ethernet
  Destination address: 10.10.10.10, VC ID: 10104000, VC status: up
    Output interface: Po1, imposed label stack {25947 524087}
    Preferred path: not configured
    Default path: active
    Next hop: 10.20.20.20
  Create time: 7w0d, last status change time: 2w2d
  Signaling protocol: LDP, peer 10.10.10.10:0 up
    Targeted Hello: 10.9.9.9(LDP Id) -> 10.10.10.10
    Status TLV support (local/remote)   : enabled/supported
      Label/status state machine        : established, LruRru
      Last local dataplane   status rcvd: no fault
      Last local SSS circuit status rcvd: no fault
      Last local SSS circuit status sent: no fault
      Last local  LDP TLV    status sent: no fault
      Last remote LDP TLV    status rcvd: no fault
    MPLS VC labels: local 2896, remote 524087
    Group ID: local 0, remote 0
    MTU: local 9100, remote 9100
    Remote interface description:
  Sequencing: receive disabled, send disabled
  VC statistics:
    packet totals: receive 8442091, send 19777721
    byte totals:   receive 2122750758, send 23155206728
    packet drops:  receive 0, seq error 0, send 0

Local interface: Te9/2.4000 up, line protocol up, Eth VLAN 4000 up
  MPLS VC type is Eth VLAN, interworking type is Ethernet
  Destination address: 10.10.10.11, VC ID: 10114000, VC status: down
    Output interface: if-?(0), imposed label stack {}
    Preferred path: not configured
    Default path: no route
    No adjacency
  Create time: 7w0d, last status change time: 2w2d
  Signaling protocol: LDP, peer 10.10.10.11:0 up
    Targeted Hello: 10.9.9.9(LDP Id) -> 10.10.10.11
    Status TLV support (local/remote)   : enabled/supported
      Label/status state machine        : remote invalid, LrdRrd
      Last local dataplane   status rcvd: no fault
      Last local SSS circuit status rcvd: DOWN(not-forwarding)
      Last local SSS circuit status sent: AC DOWN(rx,tx faults), PW DOWN(rx,tx faults)(not-forwarding)
      Last local  LDP TLV    status sent: DOWN(not-forwarding)
      Last remote LDP TLV    status rcvd: AC DOWN(rx,tx faults)(not-forwarding)
    MPLS VC labels: local 4053, remote 130927
    Group ID: local 0, remote 0
    MTU: local 9216, remote 9100
    Remote interface description:
  Sequencing: receive disabled, send disabled
  VC statistics:
    packet totals: receive 0, send 0
    byte totals:   receive 0, send 0
    packet drops:  receive 0, seq error 0, send 0

[gule1]

Then you guess an IOS software issue ?