VLAN configs on multiple separate switches 1

[FannyWhistle]

Hi,

I'm currently looking how to configure a couple of VLANs on 3com switches.

I have a 4900 and a pair of 4226T's in my computer room that I want to be 10.1.x.x, and I have 4 more 4226T's serving the users in my wiring closet that I want to be 10.2.x.x.

Do I have to set EVERY port in EVERY switch to be VLAN aware? or can I just set the 10.1.x.x VLAN in the computer room switches and set up the routing between VLANs on the uplink ports between the computer room and the wiring closet switches?

I'm not sure which to do, considering that I read somewhere else on Tek-Tips that there's a few gotchas relating to the default gateway on the default VLAN?

If I give you a little bit more background, i'm looking to hang a gateway for the clients off of the 10.2.x.x VLAN and a separate gateway to the servers off of the 10.1.x.x VLAN and have a RIP-based route between the two gateways for the two subnets.

Thanks for any info.

Cheers,
Mike.

 

[TimRegester]

You could run an uplink from the 4900 to each switch if and just make the 4900 memberships of the relavent VLANs 1 or 2 (nb VLAN 1 in this example being 10.1.x.x and vlan 10.2.x.x) with no 802.1q awareness just using port based membership. The 42xx switches could then be left in VLAN 1.

However it would be more sensible to change the vlan membership of each port on the 42xx to the correct VLAN in each case, this would provide you with maximimum flexibility in the future, protection from someone else changing the 4900 VLAN 2 port to 802.1q membership and screwing it all up and protection if the goalposts change and you have to add a third VLAN on one of the 42xx switches.

The CLI command bridge vlan modify addPort then add the VLAN ID and 1,2,3,......26 should work and you will only have to log into each stack once since you can switch units from the CLI.

I hope this helps.

 

[FannyWhistle]

Thanks Tim,

I'm loathe to use the 4900 as a distribution switch since it's only got a couple of free ports and actually sits between the two 4226T's in the computer room topology (since I run redundant gigabit loops in my network and think the 4226T's spanning tree implementation is a bit better). I use a gigabit port from the 4226T as one of the links to the 4900, and the other gigabit port as the link to the wiring closet switch.

In your experience are there any restrictions upon which numbered VLANs I should use then? as there was someone here talking about the inability to see a default route on the default VLAN - i.e. should I use all new VLANs for all ports in the network, or can I leave one set of VLAN ports on the default VLAN or is this going to cause problems?

Cheers,
Mike.

 

[TimRegester]

As a general rule VLAN 1 is used for management so make both the two vlans anything other than that. VLAN 1 will still exist on all switches and all ports will be members of it, hence the default route issue. Using other vlans makes them discreet and prevents any broadcast issues.

The 4900 will still have to route between VLANs but this could be done using the uplink in 802.1q tagging mode.

Simply give each vlan a gateway ip address as per the workstations and enable rip routing. Make the link to the wiring closet tagged and the 4900 to 4226Ts tagged and all should work fine.