Layer 2 Subinterface Configuration
This chapter contains examples of configuring L2 Subinterfaces.
A single physical interface when required to handle multiple VLAN traffic, can be divided into multiple logical interfaces called sub-interfaces.
All sub-interfaces under the physical port will use their parent port for sending and receiving data.
Sub-interfaces let you divide a physical interface into multiple logical interfaces that are tagged with different VLAN identifiers. Because VLANs allow you to keep traffic separate on a given physical interface, you can increase the number of interfaces available to your network without adding additional physical interfaces.
Note: Refer to the release note for features supported by L2 Sub-interface.
Topology
Below figure shows and example of subinterface configuration for one node with cross-connect. In this example, there is one router R1 with 2 connections
The xe1.10 and xe2.10 subinterface is created on R1
Sub-interface can be created over physical or LAG interfaces.
Note: Use dot1ad ethertype (0x8100 | 0x88a8 | 0x9100 | 0x9200) command to configure the service-tpid value on parent port of a subinterface. By this the tpid used for service tag for a subinterface may be inherited from the one applied to parent interface.
Note: For any dot1ad subinterface to be functional, dot1ad ethertype should be set to desired value as 0x88a8/0x9100/0x9200. Default value is 8100. To verify the ethertype value for the interface use show interface <subinterface> command.
Configure L2 Subinterface with cross-connect
#configure terminal | Enter configure mode. |
(config)#interface xe1 | Enter interface mode |
(config-if)# dot1ad ethertype 0x88a8 | Configure interface with tpid value as 88a8 |
(config-if)#exit | Exit interface mode. |
(config)#interface xe1.10 switchport | Creates a L2 sub-interface as xe1.10 |
(config-if)#encapsulation dot1q 10 | Configure the encapsulation as dot1q matching vlan 10 |
(config-if)#exit | Exit interface mode. |
(config)#interface xe2 | Enter interface mode |
(config-if)# dot1ad ethertype 0x88a8 | Configure interface with tpid value as 88a8 |
(config-if)#exit | Exit interface mode. |
(config-if)#interface xe2.10 switchport | Creates a L2 sub-interface as xe2.10 |
(config-if)#encapsulation dot1q 10 | Configure the encapsulation as dot1q matching vlan 10 |
(config-if)#exit | Exit interface mode. |
(config)# cross-connect CC1 | Create cross-connect with name CC1 |
(config-xc)# interface xe1.10 | Attach interface xe1.10 |
(config-xc)# interface xe2.10 | Attach interface xe2.10 |
(config-xc)#exit | Exit cross-connect mode. |
(config)#commit | Commit the transaction. |
Configure L2 Subinterface(Double-Push) with cross-connect
#configure terminal | Enter configure mode. |
(config)#interface xe1.10 switchport | Creates a L2 sub-interface as xe1.10 |
(config-if)#encapsulation untagged | Configure the encapsulation as untagged |
(config-if)# rewrite push 0x8100 200 inner-dot1q 200 | Configure rewrite push with inner vlan 200 and outer vlan 200 |
(config-if)#exit | Exit interface mode |
(config)#interface xe2.10 switchport | Creates a L2 sub-interface as xe2.10 |
(config-if)# encapsulation dot1ad 200 inner-dot1q 200 | Configure the encapsulation with inner vlan 200 and outer vlan 200 |
(config-if)#exit | Exit interface mode |
(config)# cross-connect CC1 | Create cross-connect with name CC1 |
(config-xc)# interface xe1.10 | Attach interface xe1.10 |
(config-xc)# interface xe2.10 | Attach interface xe2.10 |
(config-xc)#exit | Exit cross-connect mode. |
(config)#commit | Commit the transaction. |
Configure L2 Subinterface(Double-Pop) with cross-connect
#configure terminal | Enter configure mode. |
(config)##interface xe1.10 switchport | Creates a L2 sub-interface as xe1.10 |
(config-if)#encapsulation untagged | Configure the encapsulation as untagged |
(config-if)#exit | Exit interface mode |
(config)#interface xe2.10 switchport | Creates a L2 sub-interface as xe2.10 |
(config-if)# encapsulation dot1ad 200 inner-dot1q 200 | Configure the encapsulation with inner vlan 200 and outer vlan 200 |
(config-if)# rewrite pop-2tag | Configure rewrite pop-2tag |
(config-if)#exit | Exit interface mode |
(config)# cross-connect CC1 | Create cross-connect with name CC1 |
(config-xc)# interface xe1.10 | Attach interface xe1.10 |
(config-xc)# interface xe2.10 | Attach interface xe2.10 |
(config-xc)#exit | Exit cross-connect mode. |
(config)#commit | Commit the transaction. |
Creating a Subinterface with Encapsulation
Single encapsulation as dot1q with vlan range
configure terminal (config)#interface xe1.100 switchport
(config-if)# encapsulation dot1q 100-200
Single encapsulation as dot1ad with vlan range
configure terminal (config)#interface xe1.100 switchport
(config-if)# encapsulation dot1ad 100-200
Double encapsulation as dot1q
configure terminal (config)#interface xe1.100 switchport
(config-if)# encapsulation dot1q 10 inner-dot1q 10
Double encapsulation as dot1ad
configure terminal (config)#interface xe1.200 switchport
(config-if)# encapsulation dot1ad 20 inner-dot1q 20
Encapsulation as default
configure terminal (config)#interface xe1.101 switchport
(config-if)# encapsulation default
Encapsulation as untagged
configure terminal (config)#interface xe1.102 switchport
(config-if)# encapsulation untagged
Rewrite with push
configure terminal (config)#interface xe1.10 switchport
(config-if)# encapsulation dot1q 10
(config-if)# rewrite push 0x8100 100
(config-if)#interface xe2.20 switchport
(config-if)# encapsulation dot1q 100 inner-dot1q 10
(config-if)#exit
(config)# cross-connect CC1
(config-xc)# interface xe1.10
(config-xc)# interface xe2.10
Note: At interface xe1.10, for incoming traffic "rewrite push" will add vlan as 100 with tpid values 8100.
Note: At interface xe1.10, for outgoing traffic "rewrite push" will pop the vlan.
Rewrite with translate
configure terminal (config)# interface xe1
(config-if)# dot1ad ethertype 0x9100
(config-if)#interface xe1.10 switchport
(config-if)# encapsulation dot1ad 200
(config-if)# rewrite translate 1-to-1 0x9100 100
(config-if)#interface xe2
(config-if)# dot1ad ethertype 0x9100
(config-if)#interface xe2.20 switchport
(config-if)# encapsulation dot1ad 100
(config-if)#exit
(config)# cross-connect CC1
(config-xc)# interface xe1.10
(config-xc)# interface xe2.10
Note: At interface xe1.10, for incoming traffic "rewrite translate" will update vlan as 100 with tpid values 9100.
Note: At interface xe1.10, for outgoing traffic "rewrite translate" will update vlan as 200 with tpid values 9100.
Rewrite with pop
#configure terminal (config)#interface xe1.10 switchport
(config-if)# encapsulation dot1q 100
(config-if)# rewrite pop
(config-if)#interface xe2.20 switchport
(config-if)# encapsulation untagged
(config-if)#exit
(config)# cross-connect CC1
(config-xc)# interface xe1.10
(config-xc)# interface xe2.10
Note: At interface xe1.10, for incoming traffic "rewrite pop" will pop the vlan.
Note: At interface xe1.10, for outgoing traffic "rewrite pop" will add vlan as 100 with tpid values 8100.
Note: Push, pop and translate rewrite operations are supported with tpid values 8100/88a8/9100/9200 as symmetric operation.
No subinterfaces
#configure terminal (config)#interface xe1
(config-if)# no subinterfaces
Note: no Subinterfaces will remove all the Subinterfaces.
Note: Same physical interface will support both L2 and L3 subinterfaces.
L2SI Statistics
Enable below commands to get L2SI statistics
#configure terminal (config)# hardware-profile statistics ac-lif enable
Note: Reload the node, and then only statistics command will get effective.
Verification commands
Subinterfaces appear as any physical interface in the show running-config or the show ip interface brief output and can be configured as any other interface.
The following examples display subinterface information from various show commands.
show interface brief
R1#show interface brief | include xe1
xe1 ETH -- routed up none 10g --
xe1.10 SUBINTERFACE up -- N/A
show interface <>
R1#show interface xe1.10
Interface xe1.10
Hardware is SUBINTERFACE Current HW addr: b86a.97d0.25c5
Physical:(Not Applicable) Logical:(not set)
Port Mode is Switch
Interface index: 20484106
Metric 1
<UP,BROADCAST,RUNNING,MULTICAST>
VRF Binding: Not bound
Encapsulation Dot1q (0x8100) Virtual LAN
Outer Match: Dot1q VLAN 10
Label switching is disabled
No Virtual Circuit configured
Administrative Group(s): None
Bandwidth 1g
DHCP client is disabled.
Last Flapped: Never
Statistics last cleared: Never
RX
unicast packets 0 multicast packets 0 broadcast packets 0
input packets 0 bytes 0
jumbo packets 0
undersize 0 oversize 0 CRC 0 fragments 0 jabbers 0
input error 0
input with dribble 0 input discard 0
Rx pause 0
TX
unicast packets 0 multicast packets 0 broadcast packets 0
output packets 0 bytes 0
jumbo packets 0
output errors 0 collision 0 deferred 0 late collision 0
output discard 0
Tx pause 0
show cross-connect
R1#show cross-connect
cross-connect status
XC name Ep1 Ep2 Status
-----------------------------+----------------+----------------+-------
CC1 xe1.10 xe2.10 UP
-----------------------------+----------------+----------------+-------
AC cross-connect summary
Total : 1
Up : 1
Down : 0
R1#show running-config interface xe1
!
interface xe1
dot1ad ethertype 0x88a8
!
R1#show run interface xe1.10
!
interface xe1.10 switchport
encapsulation dot1q 10
rewrite push 0x8100 10
!
R1#show running-config interface xe1
!
interface xe2
dot1ad ethertype 0x88a8
!
R1#show run interface xe2.10
!
interface xe2.10 switchport
encapsulation dot1q 10
!
show interface xe1.10 counters
R1#show interface xe1.10 counters
Interface xe1.10
Rx Packets: 50000
Rx Bytes: 50000000
R1#show interface xe2.10 counters
Interface xe2.10
Tx Packets: 50000
Tx Bytes: 49900000