InterVLAN Routing

Hi Nityanand,
this “L3” written over the line means that both link end-points on switches are routed ports. We can add one more link interconnecting switches, make both of its end-points routed ports. Bundle links together, add IP on each end-point of port-channel and then run OSPF over it. It is no problem, should look like this.

L3%20etherchannel%20OSPF%20adjancency

Create virtual port-channel interface, make it routed port-channel and add IP on it.

SW2(config)# interface port-channel 23
SW2(config-if)# no switchport
SW2(config-if)# ip address 10.10.10.2 255.255.255.0

SW3(config)# interface port-channel 23
SW3(config-if)# no switchport
SW3(config-if)# ip address 10.10.10.3 255.255.255.0

Make physical interfaces routed ports and bundle them into port-channel. You can use interface range command for it.

SW2(config)# interface range g0/1 - 2
SW2(config-if-range)# no switchport
SW2(config-if-range)# channel-group 23 mode on

SW3(config)# interface range g1/1 - 2
SW3(config-if-range)# no switchport
SW3(config-if-range)# channel-group 23 mode on

Port-channel should be up, you can try some verification commands.

SW2# show etherchannel 23 summary

<..output omitted..>

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
23     Po23(RU)         -        Gi0/1(P)    Gi0/2(P)    

Enable IP routing on both switches.

SW2(config)# ip routing

SW3(config)# ip routing

Run OSPF process on created L3 port-channel interfaces. For example like this.

SW2(config)# router ospf 1
SW2(config-router)# network 10.10.10.2 0.0.0.0 area 0

SW3(config)# router ospf 1
SW3(config-router)# network 10.10.10.3 0.0.0.0 area 0

OSPF adjancency should come up. You can verify it.

SW2# show ip ospf neighbor 

Neighbor ID     Pri   State           Dead Time   Address         Interface
10.10.10.3        1   FULL/DR         00:00:36    10.10.10.3      Port-channel23

Edit:
Notice that ip address is configured only on virtual port-channel. There is no ip address configured on physical routed ports.

In case you shutdown one physical interface then port-channel stays up. Verify it like this.

SW2(config)# interface g0/2
SW2(config-if)# shut

SW2# show etherchannel 23 summary
Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
23     Po23(RU)         -        Gi0/1(P)    Gi0/2(D)    

Pay attention to letters in brackets.

  • Po23(RU), R means that it is layer 3 portchannel and U means that its status is up (working).
  • Gi0/1(P ), P means that interface G0/1 is active and still bundled.
  • Gi0/2(D), D tells us that interface is down, well because we did shut it down.

Is this what you was looking for?

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