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Inter-vlan Routing

I'm just a little confused and would like some clairification about a couple of things.

1) The 2950 switch does NOT support ISL, right? I was sure this was the case, but saw something on the tech. support pages that led me to believe otherwise. I'm not talking about and XL switch, just the straight 2950.

2) With 802.1q Inter-VLAN Routing, is it necessary to have an IP on the main interface on the router, or just a good idea? I plan on doing the routing between VLAN 1 and VLAN 2 on one switch and VLAN 2 and VLAN 3 on another.

Thanks for the words of wisdom.


Re: Inter-vlan Routing


when ever u want to make communication between two differnet VLAN then there is a need for the layer-3 your switch is not layer-3 switch...thats why u need to create the multiple sub interfaces on the router interface so u can have communication between differnet VLAN...and one more thing will u clear your connectivity...

please rate this post if it helps




Re: Inter-vlan Routing

1) Yes that is correct. The 2950/2955 series of switches do not support ISL.

2) Usually you do not configure IP Address on the physical interface when doing inter-VLAN routing. The only situation I can think of when you will do it is when using IOS versions earlier than 12.3(T) that did not allow you to use the dot1q native command on a sub-interface. In this case the IP Address on the physical interface will be handling untagged packets from the native VLAN. For all other VLANs you would configure sub-interfaces and configure ip addresses there. The following link might help:

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