Adding a separate subnet

[hbkhelpdesk]

We have two switches; a WS-C3550-48 and a WS-C3548-XL connected via fiber uplink ports. Both switches are on the same subnet 192.168.1.0 /24. I would like to change the subnet of the second switch, WS-C3548-XL, to be on 192.168.2.0 /24. Would it be possible to assign 192.168.2.x IP addresses to both uplink ports to achive this?

The current config for both interfaces is

interface GigabitEthernet0/1

switchport trunk encapsulation dot1q

switchport mode trunk

Or would I need to create a separate VLAN and assign both GigabitEthernet0/1 uplink ports to this VLAN?

Thank you for any assistance.

[John Blakley]

The address on vlan 1 on both devices is used for device management. Do you have routing enabled on these? What's the drive to want to change the other switch to a different subnet? Are you trying to support hosts in that subnet?

HTH,
John

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[hbkhelpdesk]

I am running out of IP addresses on 192.168.1.0 /24 and these switches are seperated by location (connected via Fiber). I need someone to point me in the right direction on how to setup a seperate subnet over two switches connected via uplink ports. The 3550 switch is layer three but I dont know if the 3548 is. Can I setup a second VLAN and route with these devices? Or, can I simply assign IP addresses to the uplink ports on both switches to be on 192.168.2.0? I currently have a similar setup with a 3750 and a 2950 where port 16 was assigned an IP on a different subnet (say 192.168.10.0 /24). There was no need to add any routes to 192.168.10.0 since it is directly connected to the 3750 switch.

[John Blakley]

You're running out of addresses, but adding a 192.168.2.0/24 to your switch isn't going to solve the issue if you aren't using it for routing. Again, the 192.168.1.x or 192.168.2.x on vlan 1 (or any vlan for that matter) is only for management purposes if routing is disabled. Your hosts that are attached to the switch would never use the IP on the switch if the switch isn't configured as L3 and being used as a default gateway for your hosts. That being said, we may need to know a little about your topology. I believe the 3548s are L2 only which means you will need something to route if you're going to go in this direction. The easy way out is if you're routing on your 3550 for this point-to-point linke, you could always add the 192.168.2.x address as a secondary address on the vlan that your 192.168.1.x addresses are on. Then you could superscope the dhcp pool by adding another scope for the 192.168.2.x subnet.

If this doesn't point you in the proper direction, please post a diagram of how this fiber is connected including what does the routing for you. At this point, I'm assuming that your 3550 is configured for routing but I could be utterly wrong

HTH,
John

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[Robert R · Accepted solution]

Are you set on using 192.168.2.0/24?  If 192.168.0.0/24 is available, then you might consider changing the vlan to a /23 since it seems the driving factor is to add IP addresses. 

192.168.0.0/23  would give you 510 IPs from 192.168.0.1 - 192.168.1.254.

Just a thought.

Rob

[hbkhelpdesk]

Thanks for the help. I think we will go with the /23 idea.