Connecting Cat6509 to Cat 2950

londint · ‎04-05-2006

Connecting a Cat 2950 to a Cat 6509 using a cross over cable. This comes up as trunk but I don’t want it to.

When it was first connected, it led to some spanning tree errors as the port vlan at both ends were different. On the C2950, I had vlan 1 and on the C6509, I had Vlan 211. I change the port vlan to 1 on the C6509 and then this was ok but now it is trunking.

I dont want to trunk on these port. What I want it to create a connection as a normal access port in say vlan 211.

How do I do this?

And then after doing the above, will routers connected to the switch be able to talk to each other via vlan 211?

I am running CatOS on the 6509 and IOS on the 2950.

Thanks

mahmoodmkl · ‎04-05-2006

HI

configure the ports as access ports for the vlan which u want.create the vlan both on 6509 and 2950.

disable trunking on the ports.see that all u r routers are in vlan which u want ie 211.

Foe eg

on 6509

set vlan 211 2/2

and on 2950

switchport mode access

switchport access vlan 211

Thanks

Mahmood

amit-singh · ‎04-05-2006

Hi,

Do the following

On 2950

conf t

int fa x/y

switchport mode access

switchport access vlan

switchport nonegotiate

On Cat 6500

If trunk is there then,

set trunk x/y off

set vlan x (vlan#) y/z (port#)

for example

set trunk 2/23 off

set vlan 100 2/23

http://www.cisco.com/en/US/products/hw/switches/ps628/products_command_reference_chapter09186a00802ccfb4.html#wp1631612

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sw_8_1/cmd_ref/setsy_tr.htm#wp1170006

HTH, Please rate if it does.

-amit singh

londint · ‎04-05-2006

Thanks Amit

The C2950 is on a remote site. The remote site have said that they do not have any VTP configured as the C2950 is being used as just a hub, so thereby the will not be able to configure vlan 100 for example on the C2950.

This leaves me with why the link came up as a trunk when the links were connected even though on the C6509, it was never configured as a trunk. I feel as if their side forced the C6509 into trunking.

So if they cannot create any extra vlan on their C2950, how else can I configure this connection as an access port?

amit-singh · ‎04-05-2006

********Why the link came up as trunk ? *****

Answer is, 2950 and 6500's support DTP (dynamic trunking protocol ) which means that if either side sends a DTP packet the other side will be able to form a trunk. This is what has happened.

Do the following thing on 2950 switchport :

conf t

int x/y --> port connected to 6500

switchport nonegotiate ** Try this command only first, it should work,if not try other **

switchport mode access

HTH, Please rate if it does.

-amit singh

londint · ‎04-05-2006

Thanks Amit.

So after doing this, can we still leave the VLAN as default VLAN 1 at both ends and it wil not trunk?.

amit-singh · ‎04-05-2006

yes, You are good to go after that.

HTH, Please rate if it does.

-amit singh

londint · ‎04-05-2006

Thank you so very much Amit. I really appreciate your help. I have another question which I will open another message for.

Thanks again.

glen.grant · ‎04-05-2006

The 2950 has a default of dynamic desirable on its ports so unless trunking is specifically shutoff on the 6500 it will create a trunk . If the 6500 trunk port is "auto" (default) or desirable the trunk link will come up , just turn the trunk off on the 6500 and the link will not trunk . You can shut it off on the 2950 also by making it an access port also.

londint · ‎04-05-2006

Thank you very much Glen.