Hey guy's,

Can anyone point me in the right direction with this question?

If you have two switches, with a router in the middle, connected via ethernet on both sides, if i'm using inter VLAN routing, do i need subinterfaces for each VLAN on the router? For example,

Fa0/0 on router is trunked and has .1,.2,.3,.4 for VLAN's 2,3,4 with subinterfaces all on /25, works fine.

Fa0/1 on same router connected to other switch, wanting to connect VLAN's 2,3,4 (also configured on 2nd switch) but can't seem to use /25 for sub's on Fa0/1 as overlaps with Fa0/0, does there even need to be more sub's on Fa0/1 or should they be connecting to 1st set of sub's on Fa0/0?

Sorry if this sounds a bit vague guy's hope someone can help

You can't have 2 interfaces in the same range on the same router (at least not ethernet)

What exactly is the design goal here? There must be a better way of doing what you are trying to do

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Its for a lab exercise i've been given so i'm pretty new to this stuff, but i'm slowly learning with some great tips on here

Basically I've got a design which goes: Switch / Router / Switch --- hosts in 3 vlans / i've configured the switch on the right and the hosts into the vlan's, i've got the router working with ospf as instructed, i'm left with the switch on the left and i'm trying to config the 3 vlan's onto that switch, which i've done, but i cant ping the router, I had a similar problem with the first switch until i config'd the sub-interfaces then bingo connectivity on the right of the design, but i dont know whether the switch on the left needs to be connected to more sub-interfaces on the router (Fa0/0), the switch on the right is connected to Fa0/1 and is up and running.

Any ideas?

Are the switches running OSPF as well? If so I would put different ip ranges on each side of the router and let the switches learn how to get to the other side via OSPF.

If they are not running OSPF, then create subinterfaces on both sides without IP addresses. Then put fa0/0.10 and fa0/1.10 into the same bridge group and put the IP address on the BVI 10 interface. Do the same for the rest.

If the router is running OSPF by itself that would make no sense...

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I've got a feeling once this is configured the next part may be to introduce a few more routers for them to route to using OSPF. At the moment i've only got the router using OSPF but ill add it to the switches and see if i can get them connecting that way, if not ill try the other way you suggested, i'm not upto bridge groups yet but there's only one way to learn!

Thanks for your advice bud your a legend

No problem. Bridge groups can be a bit tricky at first, but once you know how they work it's pretty simple.

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