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New Member

VLANS and 802.1Q Trunks vs. Port Channels

I will be installing 3548 Switches with Gigabit GBICs feeding into GB 3508''s.

The 3508's will terminate via GB trunks into 2948G-Layer 3 . Will be running VLANS which terminate at the 2948G-L3.


1) Do I have to add subinterfaces on the 2948G-L3 GB interfaces for each VLAN?

Can I even do this or do I have to use the FE ports and create Port Channels?

2) Will HSRP work on GB Trunks?


New Member

Re: VLANS and 802.1Q Trunks vs. Port Channels

am unsure about question 1.

question 2: the same operation works on cat4K (which use the same software) and I can confirm HSRP works accross portchannels, as it is one physical interface, you must use HSRP groups and i suggest a good idea to use the channel number as the HSRP group number.

back to Q1, the GB interface has to be tied to the port channel to perform intervlan routing through the backplane. If you configure subinterfaces, you will probably then have to use an external connection back into the switch. This is my understanding on the 4K, the 2948 should be the same ?

Re: VLANS and 802.1Q Trunks vs. Port Channels

Yes, you will need to add sub-interfaces per VLAN to the 802.1Q trunk links on the 2948G-L3.

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