Backbone VLAN?

chrismgeary · ‎12-06-2005

I have two 3560 distribution switches. They run EIGRP between each other, one runs RIP to our ISP and the other runs OSPF to another part of the organisation. We have 15 server and user VLANs and VLAN1 is the native.

At present, EIGRP and OSPF have free reign on the network in terms of which VLANs they form adjacencies on. I've been reading about passive-interface default and done some tests in my test lab. I want to remove as much traffic from the native VLAN as possible as I have read that this is a sensible thing to do. If I create a single "Backbone VLAN" and issue passive-interface default to all routing protocols apart from that VLAN, are there any problems with doing this? Obviously, ISP and intranet routers would have to be moved into this VLAN.

I've done numerous searches on these forums and cisco.com tech support and cannot find enough info to work out if its best practice or not. My objective is to make the LAN as secure and stable as possible by using best practices.

many thanks

Chris

amit-singh · ‎12-06-2005

Hi Chris,

Why do you want to move the routers to a new Vlan. Your native vlan is Vlan 1 and you dont want it to be a native vlan so just make any other vlan as Native vlan say vlan 100 which is not used anywhere in ur network. This way your Vlan1 traffic will be tagged and will work as secure as any other Vlan.

on switch

conf t

vlan 100

int gig x/y <-- Your trunk interface

switchport trunk encapsulation dot1q

switchport mode trunk

switchport trunk native vlan 100

regards,

-amit singh

chrismgeary · ‎12-07-2005

mainly because I have 10 switches in VLAN1 and only 2 WAN routers in VLAN1. It seems less work to move the routers rather than the native VLAN.

As to the principle of setting all interfaces to passive apart from a 'routing vlan' - is this a sensible approach? would it be considered best practice to remote routing protocol packets from user vlans?

chrismgeary · ‎12-14-2005

can anyone offer any advice?

of course it should read

"would it be considered best practice to remove routing protocol packets from user vlans?"