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New Member

Is this possible: accessing 2 vlans from a port set to vlan 1?

Hi,

We're using a Catalyst 2924,

and recently implemented VLAN's.

All ports of the switch have a static vlan 1

and port 24 has multivlan 1+2

How come that 2 of my static ports, can access both vlans??????

From the DHCP server, i get an address of VLAN2.

But setting manually an ip address, i can access VLAN1.

This problem is port based; when i swap machines, the problem remains on the same port.

How can I resolve this???

Kind Regards,

Simon.

3 REPLIES
New Member

Re: Is this possible: accessing 2 vlans from a port set to vlan

Ensure the host on port 24 does not forward.

Ensure that you do not have a device acting as a router on port 24, which is on both VLANs. Better disconnect the host on port 24 and test if the 2 VLANs can now communicate. If not that is the problem.

It might seem silly but sometimes the TCP/IP stack of hosts, instead of dropping packets, it forwards them if it knows a valid route.

Fabio Sardone

New Member

Re: Is this possible: accessing 2 vlans from a port set to vlan

Fabio,

Maybe i did not made myself very clear about port 24.

On port 24, there is another switch attached. below, you find a figure of our configuration.

The gloal is to connect the top switch to the bottom switch,

passing through a couple of existing switches.

This existing infrastructure is VLAN1, the "pass though" network is VLAN 2

There is a router on our network, but that's connected to the switch on 193.168.0.105, and that router is only for internet purposes.

Switch 193.121.106.33 (VLAN 2)

|

| ( UTP)

|

193.168.0.105

port 24 (VLAN 2)

Cisco 2900XL Fiber (VLAN 1 & 2)

|

| (Fiber)

|

193.168.0.106

Cisco 2900 port 22 (VLAN1 & 2)

!!! PROBLEM PORTS ARE HERE !!!

port 22 (VLAN1 & 2)

|

| (Fiber)

|

193.168.0.112

port 11 (VLAN

port 1 (VLAN 1 local PC)

Cisco 2950 port 12 (VLAN 2 ==> goes to a 3com switch)

Everything works fin, except for the problemports at 193.168.0.106.

The problem seems to expand... yet 6 ports have switched to VLAN 2...

And now the question : Is this setup ok, or should I implement the VLAN's in another way?

Thanks,

Simon.

Bronze

Re: Is this possible: accessing 2 vlans from a port set to vlan

Please paste the first and last switch version n config

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