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VLANS and STP

I have the situation shown in the "existing" and want to implement the "desired". As of right now there are only 2 vlans in the 4500 series switches, all subnets are in VLAN1 and need to be given their own VLAN.

The goal is to eventually have all switches uplink individually to the 4500 series.

Here are my questions:

1. If I want the full redundant config as in the "desired", how do you configure the two seperate uplinks, are they considered seperate trunks the two switches?

2. the fact that these are 3com, is there anything that needs to be considered or is the config the same conceptually?

3. The two Cisco switches gave STP configured, what all needs to be considered when enabling on the 3coms? Is there any danger in just enabling the STP on the 3coms?

4. The access switches have management interfaces, but the users have their default gateway pointing to the SVI on the Cisco 4503 correct?

5. If 4 is so, what scenario would I point the users the the access switch as their default gateway?

2 REPLIES

Re: VLANS and STP

Hi,

I am unable to view the diagram. I believe you have 2 core switches and all the access switches have 2 uplinks to each core. See the responses below.

1. If I want the full redundant config as in the "desired", how do you configure the two seperate uplinks, are they considered seperate trunks the two switches?

Yes, they are separate trunks.

2. the fact that these are 3com, is there anything that needs to be considered or is the config the same conceptually?

Auto speed/duplex (default) setting on Cisco switches mayn't work well with non-cisco devices. Hardcode the speed/duplex. Any configuration or feature you choose to use between 3com-cisco, make sure they are industry standard protocols to avoid problems.

3. The two Cisco switches gave STP configured, what all needs to be considered when enabling on the 3coms? Is there any danger in just enabling the STP on the 3coms?

802.1D STP is industry standard. You need to enable STP on 3com switches as well to avoid STP loops.

4. The access switches have management interfaces, but the users have their default gateway pointing to the SVI on the Cisco 4503 correct?

Your description of 3com indicate they are layer 2 switches. Hence, the default gateway for the hosts should be set to the SVI IP of the 4503 switch.

5. If 4 is so, what scenario would I point the users the the access switch as their default gateway?

N/A

Hope this helps!

Sundar

Blue

Re: VLANS and STP

1) YES,

the uplinks will need to be configured as trunks if they need to support more than one VLANs traffic.

2) 3com switches are fine and your design is fine. the concept of trunking or simple link connections is the same. these are menu driven and quite easy to configure if you understand how/what you need to configure. be sure to set your port speed/duplex statically, not AUTO on both the 3coms and Cisco connections.

3) no real danger in enabling STP on the 3coms and infact to get your design to work, you will have too. should be enabled by default but if they are not, go ahead and enable STP. these devices support standard STP or Rapid-STP.

(be sure to have the cisco switches use the same STP mode, STD or Rapid as you have on the 3coms)

4) YES,

the users default gateways will be the SVI IP addresses configured.

5) you would not point the users to the access switches as gateways unless you have those switches performing routing for those users subnets. in this case, you would be able to point the users default GW to the access switches.

(the 3com 4400 can perform interVLAN routing so you do have the option)

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