how can I configure two vlans to be on the same subnet (cat3750)

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Oct 14th, 2008
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I am in the process of planning an upgrade to one of our factories,the problem is the old switches cat 3524s have vlan 1 as their management vlan, and the new 3750s will have vlan 51 as the management vlan, with the same IP subnet, during the cutover I will have both old and new switches on the network

how can I bridge the 2 vlans so I can access both sets of switches, I have been looking at some of the bridging commands, but cannot get it to work,

I have tried

bridge 1 protocol vlan-bridge

int vlan 1

bridge-group 1

int vlan51

ip address

bridge-group 1

Also tried

bridge irb

bridge 1 route IP

and put the ip address on

the BVI interface

any body done this

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Gadu-Gadu Wed, 10/15/2008 - 03:29
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there is no support for ip bridging.. try to type into "cisco 3750 vlan brdige fallback briding" or something like that :)

glen.grant Wed, 10/15/2008 - 03:39
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The question is was the old 3524's trunked before ? If not then you don't have to change anything just hook it up to the new vlan . If it was trunked then you will have to create a new SVI on your 3524's for vlan 51 with the address on it and shut the vlan1 management interface down . You would have to create a layer 2 vlan for 51 also.

Richard Bradfield Wed, 10/15/2008 - 13:11
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yes there is trunking, as I have a number of vlans, I was hoping I could do some sort of bridging so that I would not have to do any changes, because I also Have APs running their Management/native vlan on 1 so need to do changes there as well...

Richard Bradfield Wed, 10/15/2008 - 21:02
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I have fixed my problem by extending vlans 1 and 51 to the site 3845 router and enabling bridging on the 3845


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