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VLAN

Lee Barron
Occasional Contributor

VLAN

Hi,

I am wanting to implement a VLAN solution for our network but am a little confused after reading about it!

We have a class C network using a single subnet and are pretty much out of IP addresses. Initially I would like to split the network into 2 subnets one for each "side" of the network.

Between the two "sides" of the network we have a Procurve 5308xl switch which will enable us to do the routing between the subnets.

Lets say we have Network A which sits to the left of the 5308 switch and network B which sits to the right of the switch.

Network A is our current subnet that currently covers everything. Network B would be our new subnet/VLAN.

Would all the config just need to be done in the 5308xl switch or would all switches on both sides need to be configured to know about the VLAN's?

Bearing in mind on each side of the 5308 we have quite a few switches not all HP and not all managed!

Any help would be appreciated.

Thanks

Lee
2 REPLIES
Pieter 't Hart
Honored Contributor

Re: VLAN

thechnically speaking you do not have to use multiple vlan's.
you can use multiple subnets within the same lan (/vlan)!
but as traffic increases , splitting into vlans has other advantages.

It's no problem to dedicate vlan2 only to ports on switch2 with one connecting port to switch1 in vlan1.
In this scenario you only need to config switch2.
Jarret Workman
Frequent Advisor

Re: VLAN

Hi Lee,

Since you have 5300's, setting up a second vlan and then routing on one or both of the 5300's could work.

As one example, you would add the second vlan 2 5300A, give it an IP address, and turn on routing.

On 5300B, you would configure vlan 2, put the majority of your ports as untagged in vlan 2, and then tag your link between 5300A and 5300B for vlan 2. The devices in vlan 2 would have the ip address for vlan 2 5300A configured as their default gateway address.

5300A would also need an IP address added for the existing vlan. The existing devices in the current network would use this ip address for their default gateway.

With this static routing configuration, the existing devices in vlan 1 can talk to the new devices in vlan 2 and vice versa.

One last piece you would need is a route of last resort on 5300A that would allow traffic for an unknown destination (internet traffic for example) to get out.

This address generally takes the place of what had been configured as the default gateway on 5300A. If a default gateway did not previously exist, then this should be the address of an upstream firewall or router that heads out towards the internet.

One last note: For your newly created vlan 2, you would need to configure a return route on your firewall or upstream router so that vlan 2 traffic can get back to the end device.