I have 30 sites I need to setup with fiber between them trunking(3550's). What are the pros and cons of using a VLAN for each site and then using one 3550 to route between all vlans or to put a route table into each switch?
If you use option 1, traffic from vlan 1 on switch 1 to vlan 2 on switch 2, will take a trip from switch 1 to the 3550 that routes between the vlans, and then from there back to switch 2. You definitely dont want a traffic pattern like this. All 3550s are layer 3 capable. If you have SMI, you can run RIP. But if you have EMI you can run EIGRP or OSPF which is a better option.
Let me ask this then. If I set them up using OSPF it is still possible to use VLANs too to seperate certain traffic? If so, does that mean that I need to specify what VLANs OSPF will run on?
Yes your can use OSPF and VLANs. You will specify what VLANs OSPF is active on by using the command:
network [network ID] [wildcard mask] area [area ID]
this command is used uner the router ospf configuration context. Don't forget that the wildcard mask is the inverse of a subnet mask.
So if your VLAN 12 has an ip address of 10.30.250.1 255.255.255.192 then your corresponding OSPF command would be "network 10.30.250.0 0.0.0.63 area 0"
This might be a stupid question but what if someone puts two address schemes that overlap each other on different vlans. Wont that cause a problem with routing?
The router or layer 3 switch will not let you assign overlapping address ranges on different interfaces. Give it a try. Here is a sample output:
Test1(config-if)#ip address 10.10.0.1 255.255.0.0
10.10.0.0 overlaps with Vlan20
If I specify VLAN 1 and 2 to use OSPF they will only route in the VLAN right? So VLAN 1 shouldn't be able to reach VLAN 2. I think you would need to use intervlan routing to accomplish this.
Also right now I use SVI and when I issue "ip routing" my VLAN1 on that switch goes down but not on VLAN 2. Any suggestions?
Yes, it will only route between vlan 1 and 2. Do you have any host connected in Vlan 1.Does it only happen when you enable IP routing ?. Paste the switch config and also the output of " show int vlan1 " before and after ip routing is enabled on the switch.
Yes there are hosts throughout the 30 3550's. The only change in the config is IP Routing. The configs are here http://whitneysolutions.com/config.htm
I am trying to do this with minimal interuption, is this possible?
Let me make sure I have this down. Create 30 VLANS for the 30 sites all with different IP addresses. Each site will have all ports enabled on the VLAN for that site (IE site 1 all VLAN1, site 2 all VLAN2). Enable OSPF on all 30 VLANS. Is this right? Now it will create its own routing tables and route between all VLAN/networks? Also say I have 60 VLANS can I create 30 on OSPF 1 and 30 on OSPF 2 so that they will not route between each other.
Also the config is above from when I enable IP Routing VlAN 1 shuts down.