[c-nsp] Cisco 6500/Sup32 Sub-interface MTU Issue

[Markus Binder]

Hi all,
I am wondering which Linecard on the Sup32 (or Sup720) Platform supports user settable MTUs on Routed Sub-interfaces?

We want to use one physical Port for MPLS Backbone Uplink and IP Downlink to a customer at the same time.
As MPLS Backbone Link we have a VLAN configured with a MTU of 9216 Bytes, as IP Downlink we want to use the "normal" 1500 Byte MTU each on separate Routed Sub-Interfaces.
The Routed Sub-interfaces are required for the support of Xconnect MPLS connectivity of the IP Downlink Port as Sup32 does not support Xconnect on SVIs without WAN Cards.

The configuration required would look like:

interface GigabitEthernet6/1
mtu 9216
no ip address
no switchport
!
interface GigabitEthernet6/1.50
encapsulation dot1Q 50
description MPLS Backbone Link
ip x.x.x.x y.y.y.y
mpls ip
!
interface GigabitEthernet6/1.100
description IP Downlink to customer
encapsulation dot1Q 100
 mtu 1500
xconnect x.x.x.x 100 encapsulation mpls


But it does not work:

SW(config)#int Gi6/1
SW(config-if)#mt
SW(config-if)#mtu 9216
SW(config-if)#no sw
SW(config-if)#no switchport
SW(config-if)#int Gi6/1.100
SW(config-subif)#encapsulation dot1Q 100
SW(config-subif)#mtu ?
  <1500-9216>  MTU size in bytes

SW(config-subif)#mtu 1500
% Sub-interface GigabitEthernet6/1.100 does not support user settable mtu

Any other ideas of how to achieve that?

Best regards,

Markus Binder
--
Globalways AG
Neue Brücke 8
D-70173 Stuttgart
Germany