mixing sub interfaces with vlan interfaces

Unanswered Question
Jul 2nd, 2009

I have a 6509 running 7 gig interfaces, each interface is using sub interfaces to route vlans however It does not appear that I can span a vlan across multiple physical interfaces. I would like to span 1 given vlan across all switch ports and was wondering if i could use a vlan interface for this? how would I assign the physical interfaces, as trunks? I do not want to remove the sub interfaces as we can not convert those at this time.


Thank you,

Lawrence


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Jon Marshall Thu, 07/02/2009 - 10:57

Lawrence


Not entirely sure i follow. When you say "span" are you talking about port monitoring ie. span/rspan/vpsan or do you just mean you want to be able to allocate multiple ports into the same vlan ?


Assuming the second could you explain your topology a little more ie. why are you using subinterfaces at present.


The short answer to your question is yes you can create a L3 SVI for the vlan and then on that switch just allocate certain ports into that vlan ie.


int gi0/1

switchport access vlan


or if the ports are on another switch you can either


1) create a trunk from your 6500 to that switch which allows at a minimum your new vlan


OR


2) just create an access port that is in your new vlan.


As i say it's difficult to be be precise as your topology is not clear.


Jon

lordsporkton Thu, 07/02/2009 - 16:45

So my network is a 6509 at core going to 3 different network segments, the 6509 is the only layer3 device, everything else is layer2. I was referring to your second option, I want one vlan across more than one port.


We are running sub interfaces because the 6509 replaced a 12000(using sub interfaces, we just kind copied and pasted the config from 12k into 6509) which was setup way before me and since we have over 150 vlans per interface we haven't been too inclined to make a switch, other than this little problem we really don't have a reason to.


When I say mix I dont mean just using subs and vlan interfaces on the same switch, i mean on the same interface. Like have one interface that is using both subs and acting as a trunk.


I can't really switch everything to vlan interfaces right now, the sub interfaces kind of have to stay for now. but I also need the cross vlan connectivity if possible.


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