5372XL Routing

[Elmer Zaglauer]

Hi,

I would like to route between subnetts without
building vlans. Is that possible with the 5372XL?
Can I use secondary addresses?

Regards

Elmer Zaglauer

[Markku Leinio]

You have to use VLANs when routing with 5300XL.

You can, however, leave all ports as untagged so that other devices won't know about 5300XL's VLAN settings.

Example: you want to route between A1 (192.168.100.1/24) and A2 (192.168.200.1/24):

vlan 100 (for example)
ip address 192.168.100.1/24
untagged a1

vlan 200
ip address 192.168.200.1/24
untagged a2

ip routing

Now the switch knows how to route between 192.168.100.0/24 and 192.168.200.0/24 networks, which are connected to A1 and A2, respectively. No other device will know about the VLAN numbers, and no other 802.1Q-capable devices are needed.

[Elmer Zaglauer]

Thanks for the answer,

but that is not what I want to do.

I have 3 networks for example
10.1.1.0 255.255.255.0
10.1.2.0 255.255.255.0
10.1.3.0 255.255.255.0

The Endstations are mixed all over the network.
At the moment there is a CISCO Router as Default
Gateway 10.1.1.1 ans with secondary addresses
10.1.2.1 and 10.1.3.1
The 5372XL should become the knew Default Gateway
if he can do the same.
Only the default VLAN 10.1.1.1 and secondary
adresses 10.1.2.1 and 10.1.3.1

Elmer

[Michael Glaubig]

Yes you can do exactly what you want. On the revision of the manual I have it is page 7-9, which I can't attach because it's over 7MB, but you can download directly from the HP support site for the 5300xl series switch. You're creating secondary IP addresses for the default VLAN interface. You can only do this at the CLI:

vlan ip address secondary

Some stipulations for using this functionality (check the entire section on Configuring IP Addressing - section 7):

1. You MUST define static IP addresses on the switch to define secondary IP addresses

2. You can only assign 7 secondary IP addresses.

3. There may be DHCP issues for your clients where a client ends up in a subnet they aren't supposed to because one DHCP server answered before another. If you are using a separate switch for each subnet with a DHCP server on each switch, you would never run into this problem given the config you posted. It's a different ballgame if you want to consolidate to a single switch.

I do agree with Markku that you should use VLANs, as I would imagine that there was some reason to keep those subnets routed instead of on one large subnet like 10.1.0.0/16 (255.255.0.0). Or you could use something like:

10.1.0.0/22 (255.255.253.0)

The above would more than cover the entire IP range you listed in a single subnet with no need for a router to communicate between them.

Using the large subnet would elimate the need for the router entirely, but signifcantly increase broadcast traffic, which is probably the reason for the subnetting in the first place. The switch can be setup for DHCP relay so you only have to maintain a single DHCP server.

Without using VLANs you won't actually reduce this traffic to the clients. In your current setup, your router is most likely completely bogged down with routing packets and looking at broadcast traffic from 3 subnets, which is probably why you're contemplating getting a routing switch. You can still keep your clients spread out as they are, but you'll need to configure the switch (and where the clients plug in) so that those clients end up on their respective VLANs.

[Michael Glaubig]

My last post should have listed the netmask as 255.255.252.0 instead of 255.255.253.0 for the range listed as 10.1.0.0/22.

[Stuart Teo]

Hi,

Yes, it is possible to do what you want.

1) you need to create 3 VLANS and assign a mgmt IP addr to each of these VLANs. e.g. 10.1.1.1 to VLAN-1, 10.1.2.1 to VLAN-2, 10.1.3.1 to VLAN-3.

2) assign ports to each of these VLANs

3) connect broadcast domain 1 (10.1.1.0/24) to a VLAN-1 port. Hosts in this broadcast domain will point to 10.1.1.1 as their default gateway.

4) connect broadcast domain 2 (10.1.2.0/24) to a VLAN-2 port. Hosts in this broadcast domain will point to 10.1.2.1 as their default gateway.

5) connect broadcast domain 3 (10.1.3.0/24) to a VLAN-3 port. Hosts in this broadcast domain will point to 10.1.3.1 as their default gateway.

6) turn layer 3 routing on using your telnet/ssh logon and the menu system

7) add static routes or turn appropriate interior routing protocol(s) on using CLI. e.g. ospf, rip1, rip2

[Elmer Zaglauer]

Hi,
thanks for all your answers. In the meantime I
had the possibility to test the scenario and
it worked. I configuered three adresses for
vlan 1.
There is only one mistake in the documentation
and also in the cli help.
If you configure the second IP Address with
the extension you get an error.
You have to do it without the
extension.

Regards

Elmer