c2950 to c2950 vlan connection problem

[r.sneekes]

I am having a problem connecting a c2950 through a single vlan port to another c2950 port in native vlan (1).

I have one c2950 in which i changed the managment vlan to 10. I changed one port on that switch to vlan 10 (non trunk) and connected it to another c2950 to a port in its native vlan 1. Both switches are in the same ip space lets say one has 10.10.10.1 and the other 10.10.10.2 and since i linked vlan 10 to vlan 1 on the other switch they should be able to communicate with each other.

But that's the problem they don't. Another strange thing is when i look in the mac-adress-table of the second switch(vlan1) i see mac-adressen of oher vlans then 10 now how is this possible since the other port is dedicated vlan 10 i should not see mac-adresses from other vlans.

i solved the problem by using the default managment vlan instead of vlan10 it works but not the way i like it to work.

anyone got an idea what the problem can be? Bug ? Or i am missing something here?

[jfraasch]

One of the major benefits of VLANs is to control broadcast domains. That means that information from one VLAN will not go to another VLAN by default because that is what a VLAN is designed to do. The only way to get packets from one VLAN to another is with a router. Packets have to be routed between VLANs.

There are two ways to solve it- 1) You can plug each switch into different ethernet ports on a router or 2) you can plug both switches into the same port on a router but run a VLAN trunking protocol like 802.1q. You would need a router with a fastethernet port (10mb need not apply).

[r.sneekes]

Now that's not right. I an normal case it is only possible to link vlan though a router on layer 3 of the osi model. But i just linked them at layer 2. One port is configured as access port which means it should sent out regular packets without the vlan information.

Those packets are recieved by the other switch in another VLAN say 1 thus they will be able to communicate between the two vlan ( if there in the same ip network ofcource). I have linked several switches this way and it works fine.

[n.titchener]

Your problem is your connecting the switch to an access port and expecting to manage it. Ports configured as access ports strip all vlan information before sending the data out the port. Therefore anything connected to the port is by default in the vlan configured on the port. If you want to be able to manage the switch you should consider configuring the port as a trunk port and defining a single vlan as the management vlan. Keep it simple.

[r.sneekes]

I only have 1 managment VLAN 10. The same access vlan 10 is configured on the port to the other switch. So traffic from the switch's managment interface should just be able to go through that port untagged. And then arrive at the other switch in vlan1

[sbrobak]

Agree that this is strange. What ver. do you run?

[r.sneekes]

This is our software version:

Version 12.1(6)EA2c