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New Member

Isolate VLANs on single 2950

I have created multiple VLANs on a 2950 but find that users on one VLAN can see devices on the other VLANs without going though the router or firewall. Is there an easy way to segment the VLANs or ports on the switch to isolate the VLANs? This would turn the switch into multiple switches.

6 REPLIES
Purple

Re: Isolate VLANs on single 2950

They should not be able to see each other if they are on different vlans . sounds like something is not configured right . If you can post the config , along with a show vlan command maybe we can help.

New Member

Re: Isolate VLANs on single 2950

Here is the config file. Show commands to follow...

Re: Isolate VLANs on single 2950

Hi Friend,

Your config is simple and straight forward. If you are sure that machines are not at all hitting any layer 3 devices for inter vlan communication then make sure you have no cable cross connected on the same switch on 2 ports assigned to 2 different vlans.

Regards,

Ankur

New Member

Re: Isolate VLANs on single 2950

I believe that the problem may have been caused by plugging into an unassigned port. Port 1 was not assigned to a vlan when I originally did the testing. I caught the error in dumping out the config. After correcting the error (assigning interface 1 to vlan1), things appear to be working OK.

This allows me to manage the switch from the regular network and still have the multiple isolated LANs. The important issues appears to make certain that all ports are assigned so that a bad connection will not screw up the works.

Re: Isolate VLANs on single 2950

Hi Glen,

Though it looks weird but it happens sometime that machines on one vlan are able to talk machines in another vlans without using layer 3 device and that is known as "vlan bleeding"

The reason is if you just take a single cross over cable and connect to 2 ports on same switch like a loop and assign the 2 ports in 2 different vlan machines in those 2 vlans will start talking to each other.

Any frame when comes out of the access port it is just a frame with no vlan identification and once it hits the port vlan id is associated to the frame and the vans id is the one for which port is been configured.

Regards,

Ankur

Purple

Re: Isolate VLANs on single 2950

Understood but without a cable bridging 2 different vlans you should not be able to see users in different vlans.

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