Different physical interfaces with same Vlan ID

[P. Muilman]

Hello,

Can we configure the same vlan id on two different physical interfaces on a ASR9010?

I found this in the documentation page 1022:
http://www.cisco.com/en/US/docs/routers/crs/software/crs_r4.3/interfaces/command/reference/b_interfaces_cr43xcrs.pdf
"All VLAN IDs must be unique among all subinterfaces configured on the same physical interface"

Is this possible on a ASR9010?

interface GigabitEthernet6/20.2
description connection vlan 2 interface A 
encapsulation dot1Q 2 
vrf forwarding customer A 
ip address 10.10.10.10 255.255.255.0

interface GigabitEthernet6/10.2
description connection vlan 2 interface B 
encapsulation dot1Q 2 
vrf forwarding customer B 
ip address 11.11.11.11 255.255.255.0

[Nicolas Fevrier · Accepted solution]

Hello,

yes you can

VLAN IDs are only locally significant in your L3 interfaces, so no problem.

Cheers,

N.

[P. Muilman]

Hello Nicolas,

This is great.

Do you have an example or documentation link?

Maybe a piece of configuration where you configured this.

Thanks in advance.

Greetings, Peter

[Nicolas Fevrier · Accepted solution]

Hi Peter,

I'm not sur the particular case of re-using the same vlan ID on different L3 interfaces is particularly documented, but if I start a config on a real router based on your example:

RP/0/RP1/CPU0:A#conf

Wed Jul  3 17:24:22.643 PDT

RP/0/RP1/CPU0:A(config)#vrf custA

RP/0/RP1/CPU0:A(config-vrf)#address-family ipv4 unicast

RP/0/RP1/CPU0:A(config-vrf-af)#exit

RP/0/RP1/CPU0:A(config-vrf)#exit

RP/0/RP1/CPU0:A(config)#vrf custB                  

RP/0/RP1/CPU0:A(config-vrf)#address-family ipv4 unicast

RP/0/RP1/CPU0:A(config-vrf-af)#exit

RP/0/RP1/CPU0:A(config-vrf)#exit

RP/0/RP1/CPU0:A(config)#int GigabitEthernet0/4/3/3.2

RP/0/RP1/CPU0:A(config-subif)#dot1q vlan 2

RP/0/RP1/CPU0:A(config-subif)#vrf custA

RP/0/RP1/CPU0:A(config-subif)#ipv4 address 4.5.6.7/30

RP/0/RP1/CPU0:A(config)# exit

RP/0/RP1/CPU0:A(config)# int GigabitEthernet0/4/3/2.2 

RP/0/RP1/CPU0:A(config-subif)#dot1q vlan 2  

RP/0/RP1/CPU0:A(config-subif)#vrf custB                     

RP/0/RP1/CPU0:A(config-subif)#ipv4 address 5.6.7.1/30       

RP/0/RP1/CPU0:A(config-subif)#exit

RP/0/RP1/CPU0:A(config)#show

Wed Jul  3 17:29:00.889 PDT

Building configuration...

!! IOS XR Configuration 4.3.1.23I

vrf custA

address-family ipv4 unicast

!

!

vrf custB

address-family ipv4 unicast

!

!

interface GigabitEthernet0/4/3/2.2

vrf custB

ipv4 address 5.6.7.1 255.255.255.252

dot1q vlan 2

!

interface GigabitEthernet0/4/3/3.3

vrf custB

ipv4 address 5.6.7.1 255.255.255.252

dot1q vlan 2

!

end

RP/0/RP1/CPU0:A(config)#commit

Wed Jul  3 17:29:03.906 PDT

RP/0/RP1/CPU0:A(config)#show run int GigabitEthernet0/4/3/2.2

Wed Jul  3 17:29:33.799 PDT

interface GigabitEthernet0/4/3/2.2

vrf custB

ipv4 address 5.6.7.1 255.255.255.252

dot1q vlan 2

!

RP/0/RP1/CPU0:A(config)#sh run int GigabitEthernet0/4/3/3.3

Wed Jul  3 17:29:36.795 PDT

interface GigabitEthernet0/4/3/3.3

vrf custB

ipv4 address 5.6.7.1 255.255.255.252

dot1q vlan 2

!

RP/0/RP1/CPU0:A(config)#

Hope it helps,

Cheers,

N.

[P. Muilman]

Hello Nicolas,

This is exactly what I needed. Thank you.

The last answer you configured only gig0/4/3/2.2 and gig0/4/3/3.3 the same. And the last show command you probably wanted: show run int GigabitEthernet0/4/3/3.2 to show customer A, as you configured in the above text.

Doesn't matter.

Your answer is clear and you were a great help.

Regards, Peter