Routing between buildings

Unanswered Question
Dec 21st, 2009

Our current network is setup such that each building is on it's own vlan.  We would change our setup so that we are routing between buildings instead.  Our core has 3560's and the building we would like to route between have 3560's as well. My problem/question is, we have some devices in the remote buildings such as printers that are setup on vlan1 with static addresses.  As soon as we change the link between the core and the remote building to a L3 link, those printers are unable to communicate with the main building since they are are the same subnet as devices in the main building.  Is there a way to make routing between those devices and the rest of the network work without changing the ip address of those devices or is that the only solution?

Thanks in advance.

Jeff

I have this problem too.
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Jon Marshall Mon, 12/21/2009 - 09:51

jjnagel102 wrote:

Our current network is setup such that each building is on it's own vlan.  We would change our setup so that we are routing between buildings instead.  Our core has 3560's and the building we would like to route between have 3560's as well. My problem/question is, we have some devices in the remote buildings such as printers that are setup on vlan1 with static addresses.  As soon as we change the link between the core and the remote building to a L3 link, those printers are unable to communicate with the main building since they are are the same subnet as devices in the main building.  Is there a way to make routing between those devices and the rest of the network work without changing the ip address of those devices or is that the only solution?

Thanks in advance.

Jeff

Jeff

You have 3 options

1) use P2P routed links between the 3560s only and then you need to readdress the printers

2) have a routed link for all other vlans but also have a L2 link purely for the printers - this obviously requires more fibre

3) Make the link a L2 trunk and carry vlan 1 traffic as L2 and then route the other traffic via a dedicated vlan ie. you have a vlan that no devices are in on both 3560 switches. You then route traffic over this vlan for non-printer traffic.

Option 3) is a bit of a messy setup and i wouldn't recommend it. You are still running L2 across the uplink which means STP.

Option 2) is a sort of halfway house.

Option 1) is the one to go with if you can but you do need to readdress printers. Bear in mind though that you shouldn't have any end user devices in vlan 1 anyway whether that be clients/servers/printers so it may be a good time to readdress anyway.

Edit - is there a specific reason you want to route ?

Jon

jjnagel102 Mon, 12/21/2009 - 10:17

Thank you for the reply.

I think option 1 seems to be the best option.

The only reason I was considering L3 between the buildings is at one time another engineer suggested it as he said it gives you better failover and manageability and also better separation in case there are issues on one of the segments.

Thanks again.

Jeff

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