HP 5412: Configure Multiple Subnets on 1 VLAN to work with VRRP and Use the switche as DHCP Serv

[NyikoT2013]

We have recently purchased 2x HP 5412 switches, key deliverable with the switches are as follows:

1. Have configured  6x /24 subnets on one VLAN and we need to have VRRP work on all of the subnets, currently VRRP only works on one  subnet (primary)
2. 3x of the /24 subnets on the VLAN are DHCP Addresses, we configured IP helper address pointing to the our DHCP server however that only works on one subnet (primary).

(Please note that if we assign the subnets to each vlan it works, however since we have a flat LAN this option is not feasible)

Can you please advise how we can have the aforementioned working without having to assign the subnets to their own VLAN’s, also can the 5412 switches work as DHCP servers?

Your help is much appreciated.

[paulgear]

Hi NyikoT2013,

What is the reason you are assigning multiple subnets to the same VLAN?  This is definitely not the desired way of setting up a new network.

[Vince_Whirlwind · Accepted solution]

I'm pretty sure the 5412 doesn't offer a DHCP server, however you can buy a server module to slot into it.

If you have a big flat LAN, you might as well just use a big /21 subnet. All you gain from lots of little subnets is excessive complication.

Alternatively, use 6 subnets, put each on its own VLAN, then provide those VLANs out to access switches as untagged on the downlink to the remote switch that doesn't have VLANs on it.

If you have all your subnets mixed up and all over the place, then that's a different story. You should fix your design first, I think.

As far as VRRP goes, I seem to recall reading in the manual something about it supporting 64 IP addresses per VLAN, or 64 VRRPs per VLAN or something. I recall thinking to myself - "What is this, the '90s? Why would anybody use more than one subnet on a single VLAN?".

[NyikoT2013]

Hi Paulgear,

The reason is that we have a flat network, servers are on static addresses and users to be on DHCP. after the installtion of the HP 5412 switches we will replace the access switches but only 6 months from now, thus we need to find a way to get the business going until then.

Kind regards,

Nyiko

[Vince_Whirlwind]

What make/model are your current edge switches?

Your best bet may be to implement your VLANs right now. It isn't difficult. Certainly much easier than creating a huge mess.

[paulgear]

I agree with Vince here.  I don't see static server IPs as justification for running multiple subnets on the same VLAN.

[NyikoT2013]

Hi Vince and Paul

Many thanks for your input and assistance, we have decided to implement basic VLAN's with the existing switches (legacy 3com 4200) until we purchase latest HP Procurve switches.

Kind regards,