Cisco 7600 MUX-UNI on SRE IOS

ciscocisco-6500cisco-7600cisco-catalystmpls

I know that MUX-UNI can only be configure on a 7600 running certain IOS version, SR and SX I believe. Does that not include SRE?

Logged into a 7600 running 12.2(33)SRE9a, with the following configuration;

interface GigabitEthernet8/3
 description Link to a box
 no ip address
!
interface GigabitEthernet8/3.123
 description L3 link to a box
 encapsulation dot1Q 556
 ip address 10.21.225.65 255.255.255.248
!
interface GigabitEthernet8/3.456
 description PWE3 to a box
 encapsulation dot1Q 920
 xconnect 172.16.25.25 1026 encapsulation mpls
  mtu 1500

When I try to reconfigure this as a MUX-UNI interface the following happens;

r1(config-if)#int gi8/3
r1(config-if)#switchport 
Subinterfaces configured on this interface will not be available after mode change. To re-use reserved internal vlans, subinterfaces need to be deleted before changing the mode.
Proceed with the command? [confirm]

I can't find any Cisco doc's that say "yes" or "no" definitively on this.

Update:

The supervisor is a RSP720-3CXl-GE. The line card I was trying to configure is an old WS-X6516A-GBIC. But I thought this wasn't depending on the line card but the IOS. I configured another port on that line card and selected "confirm" and sure enough it shut down and removed the sub-interfaces. I tried to then configure the port as a switchport first and then add sub-interfaces but I couldn't assign an IP address to the sub-interface;

r1(config)#do show run | b 8/1
interface GigabitEthernet8/1
 switchport
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 58,59
 switchport mode trunk
!
interface GigabitEthernet8/1.58

r1(config)#int gi8/1.58
r1(config-subif)#ip ?
Interface IP configuration subcommands:
  access-group        Specify access control for packets
  admission           Apply Network Admission Control
  auth-proxy          Apply authenticaton proxy
  dhcp                Configure DHCP parameters for this interface
  header-compression  IPHC options
  rsvp                RSVP Interface Commands
  vrf                 VPN Routing/Forwarding parameters on the interface

I tried the same configuration on a different line card, WS-X6748-GE-TX, same result, couldn't configure an IP address because the option is not given under the sub-interface configuration mode.

Best Answer

MUX-UNI support:

It looks like you're trying to configure a MUX-UNI with:

  • A Layer3 interface on Vlan 556
  • A Vlan-mode PW on Vlan 920

The WS-X6516A is considered a Catalyst 6500 / Cisco 7600 LAN Card; LAN cards have some feature restrictions... one of the restrictions is how you configure a Layer3 interface on a LAN card with dot1q encapsulation.

When you're building a MUX-UNI combination of Pseudo-Wire services, and Layer3 services on a dot1q-trunked Catalyst 6500 LAN card, you must do the following:

  • Configure the Layer3 services on an SVI. Direct Layer3 subinterface configuration on the LAN switchports is not supported on Sup720
  • Configure the Pseudo-wire as a subinterface of the LAN card (omit the PW vlan from the dot1q trunk though.

I'll use your example...

interface GigabitEthernet8/1
 switchport
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 556
 switchport mode trunk
 switchport nonegotiate
!
interface GigabitEthernet8/1.123
 ! Configure PW-ID 1026 on Vlan 920, note that vlan-920 is *not* explicitly trunked on Gi8/1
 encapsulation dot1q 920
 xconnect 172.16.25.25 1026 encapsulation mpls
  mtu 1500
!
interface Vlan556
 no shutdown
 ! insert optional VRF configuration here
 ip address 192.0.2.254

If you use this configuration as a template, MUX-UNI will work for you.

What was wrong with your configuration

  • You tried to use a Layer3 IP subinterface directly on the switchport, which is not supported on 6500 / 7600-series LAN cards and Sup720
  • The original MUX-UNI configuration on Gi8/3 was not made a switchport first.

Catalyst6500 LAN Card IP subinterfaces

Because Catalyst6500 Vlans have a global scope throughout the chassis, LAN cards on Sup720 support a routed dot1q subinterface, as long as you have not used that same vlan elsewhere... example:

! ensure vlan 100 is unused, so we can use it on a Gi4/1 subinterface
no vlan 100
interface GigabitEthernet4/1
 no switchport
interface GigabitEthernet4/1.100
 encapsulation dot1q 100
 ip address 192.0.2.1 255.255.255.0
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