Layer 3 Subinterface Configuration

OcNOS-SP : Layer 3 Guide : Layer 3 Unicast Configuration Guide : Layer 3 Subinterface Configuration

This chapter contains examples of configuring 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 a physical port will use their parent port for transmitting and receiving data.

Sub-interfaces can be used for various purposes, as for inter-vlan routing to happen when router has only one physical interface, two sub-interfaces each with different IP network can be created under it and data can be routed between them.

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 L3 Sub-interface.

Topology

Figure 28-145 shows and example of subinterface configuration. In this example, there are two routers, R1 and R2, and the eth1 interface of R1 is connected directly to eth2 of R2 using an Ethernet cable.

Subinterface connections

The eth1.10 subinterface is created on R1, and eth2.10 is created on R2.

Note: Layer 3 Subinterfaces can be created on physical and LAG interfaces.

Creating a Subinterface

#configure terminal	Enter configure mode.
(config)#interface eth1	Enter interface mode
(config-if)#interface eth1.10	Creates a sub-interface as eth1.10
(config-if)#encapsulation dot1q 10	Configure the encapsulation as dot1q matching vlan 10
(config-if)#ip address 10.10.10.1/24	Assigning IP address to sub-interface
(config-if)#commit	Commit the candidate configuration to the running configuration
(config-if)#exit	Exit interface mode

Creating a Subinterface with Encapsulation

Double encapsulation as dot1q

#configure terminal	Configure terminal
(config)#interface eth1.1010	Configure subinterface
(config-if)# encapsulation dot1q 10 inner-dot1q 10	Configure encapsulation with inner tag
(config-if)#ip address 192.168.1.50/24	Configuring ip address
(config-if)#commit	Commit the candidate configuration to the running configuration
(config-if)#exit	Exit configure mode

Double encapsulation as dot1ad

#configure terminal	Configure terminal
(config)#interface eth1.20	Configure subinterface
(config-if)# encapsulation dot1ad 20 inner-dot1q 20	Configure encapsulation with inner tag
(config-if)#ip address 192.168.2.50/24	Configuring ip address
(config-if)#commit	Commit the candidate configuration to the running configuration
(config-if)#exit	Exit configure mode

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 0x8100. To verify the ethertype value for the interface use show interface <subinterface> command.

L3SI Statistics

Enable below commands to get subinterface statistics

#configure terminal	Configure terminal
(config)#hardware-profile statistics ac-lif enable	Enable hardware profile statistics
(config)#commit	Commit the candidate configuration to the running configuration
(config)#exit	Exit configure mode

Note: Reload the node, and then only statistics command will get effective.

Displaying Subinterfaces

In OcNOS, subinterfaces appear as any physical interface in the show running-coccnfig 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.

Note: The below command output is just for reference and is not directly related to the configuration provided above

show interface brief

RTR1#show interface brief

Codes: ETH - Ethernet, LB - Loopback, AGG - Aggregate, MLAG - MLAG Aggregate

FR - Frame Relay, TUN -Tunnel, PBB - PBB Logical Port, VP - Virtual Port

CVP - Channelised Virtual Port, METH - Management Ethernet, UNK- Unknown

ED - ErrDisabled, PD - Protocol Down, AD - Admin Down, PD(Min-links) - Protocol Down Min-links

DV - DDM Violation, NA - Not Applicable

NOM - No operational members, PVID - Port Vlan-id

HD - ESI Hold Timer Down

--------------------------------------------------------------------------------

Ethernet Type PVID Mode Status Reason Speed Port

Interface Ch #

--------------------------------------------------------------------------------

ce49 ETH -- routed up none 100g --

--------------------------------------------------------------------------------

Interface Type Status Reason Speed

--------------------------------------------------------------------------------

ce49.2 SUBINTERFACE up -- 0

ce49.3 SUBINTERFACE up -- 0

ce49.4 SUBINTERFACE up -- 0

ce49.5 SUBINTERFACE up -- 0

ce49.6 SUBINTERFACE up -- 0

show ip interface brief

RTR1#show ip interface brief

'*' - address is assigned by dhcp client

Interface IP-Address Admin-Status Link-Status

ce49 unassigned up up

ce49.2 49.49.2.1 up up

ce49.3 49.49.3.1 up up

ce49.4 49.49.4.1 up up

ce49.5 49.49.5.1 up up

ce49.6 49.49.6.1 up up

show ip ospf neighbor with VRF enabled

RTR1#show ip ospf neighbor

Total number of full neighbors: 2

OSPF process 1 VRF(default):