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New Member

creating VLANS

I have a question, I'm going to create VLAN's on a 2950 switch. The network i'm doing this on is up and can not be brought down. You guys don't see any great risk in doing this in the middle of the day, or would you wait for the maintenance window?

thanks Greg

6 REPLIES
New Member

Re: creating VLANS

Creating the VLANs is no problem, it's when you assign the ports that you will have a service interuption. Although it happens very quick, what are you doing for Layer 3 connectivity? Do you need to route between the VLANS? If so then you want to have your router privy to the VLANS prior either with 802.1q or ISL.

New Member

Re: creating VLANS

Its a basic setup, I have th 2950 with 4 ports feeding switches downstream, and 1 uplink to a cisco 7260 router. There is no immideiate need to route between the vlans but it is something that I may do at a later time. I'm basically going to use port 1 as a trunk, and ports 2-5 as seperate VLAN's

thanks Greg

New Member

Re: creating VLANS

OK have 1 more question. I plan on using ISL on the trunk, and the network I want to segment with VLAN's are all the same subnet. I only want to create VLANS on the physical port face not at a logical level. So can I use the same IP address for each subinterface on the router? if I cant how can I do what I want to do.

example: router 7206 fa0/0 ip address 172.31.32.1

switch 2950 (ip address 172.31.32.4), int fa0/1 (uplink to router), int fa0/2 to marconi switch IP address 172.31.32.5, int fa0/3 to marconi switch IP address 172.31.32.30, int fa0/3 to arconi switch IP address 172.31.2.47, int fa0/4 to marconi switch IP address 172.31.32.60

I only want to implement the vlans at the 2950 ports 1-4. any help would be great.

Greg

New Member

Re: creating VLANS

The 2950 does not support ISL trunking. ISL is a Cisco proprietary trunking protocol. They are moving to 802.1q.

New Member

Re: creating VLANS

For your vlan setup, there is article that might be of help to you.

http://www.cisco.com/warp/public/473/50.shtml

Cheers.

New Member

Re: creating VLANS

1. Why do you say you want to create VLANs in the same subnet? You create VLANs to put segments of your network in different broadcast domains. So the different VLANs will be in different subnets.

2. Each of the sub-interfaces have to be in different subnets.

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