Re: Setting up Switch module on 2951 - Page 2

Patrick McHenry · ‎09-19-2012

Hi,

I'm trying to set up a 2951 with a 24 port switch module. I want the ports to act similiarly to the ports on an 881 router - where I assign the VLANs on the router and I set the VLANs to the switchport interfaces.

I would like to be able to create the VLANs on the router portion of the 2951 and then, enter the switch module and configure the Ports to the VLANs but, how do I logically connect router to the switch? Is it an internal logical interface - meaning how are the VLANs getting from the router to the switch?

Thanks, Pat.

Patrick McHenry · ‎09-20-2012

Thanks, Reza.

I'm going to try it out. Should I create the VLANs on both the router and switch or should I only create the VLANs on the switch?

The config for the interface 2/0 (1.1.1.1) is not going to interfere with any routing or traffic flow is it?

Also, about the layer 3 connection between the router and switch module - ould I instead, give the switch a VLAN 10 ip and manage the switch by telneting to it from the router? Then I could get rid of the whole extra logical interface config? Or will it still be needed?

Thanks again, Pat.

Reza Sharifi · ‎09-20-2012

Pat,

I'm going to try it out. Should I create the VLANs on both the router and switch or should I only create the VLANs on the switch?

You don't need to create any vlans on the eouter, just the switch.

The config for the interface 2/0 (1.1.1.1) is not going to interfere with any routing or traffic flow is it?

no, it is not. That could be any ip and that is for you to jump from the router to the switch

Also, about the layer 3 connection between the router and switch module - ould I instead, give the switch a VLAN 10 ip and manage the switch by telneting to it from the router? Then I could get rid of the whole extra logical interface config? Or will it still be needed?

yes, you could, since vlan 10 in on the trunk, all you need is to create an SVI on the switch and give it an ip address in the same range as vlan 10.

HTH

Good Luck

Patrick McHenry · ‎09-20-2012

I cannot create sub-interfaces on the logical, g2/1 port.

mchenry(config)#int g2/1

mchenry(config-if)#no switchport

Command rejected: Not a convertable port.

mchenry(config-if)#

mchenry(config-if)#exit

mchenry(config)#int g2/1.10 ?

% Unrecognized command

mchenry(config)#int g2/1.10

But couldn't I make the g2/1 a trunk port that links with the g0/25 switchport and then, create the vlan interfaces on the router. Allow the VLANs accross the trunk and assign the ports to the appropriate VLAN?

Thanks, Pat.

tg74b2000 · ‎11-16-2012

That's the way I have it configured. If anyone knows how to get the sub-interfaces on g2/0 to work, please chime in. I am at a loss as I was able to do so with my 3825.

The difference I see with the 2951 is the 2 backplane interfaces to the switch module. I set up sub-interfaces on the router's G2/0 interface and configured port G0/26 on the switch module as a trunk port, and no dice. Configuring G2/1 on the router a trunk, creating VLAN interfaces, and setting port G0/25 on the switch module as a trunk does work. The issue is that I would like to keep with the sub-interfaces as that is the way my program has been doing it for a couple of years now. The more I can stay with a known baseline, the easier it is for guys in the field to configure and trouble shoot

Thanks,

Terrence

Patrick McHenry · ‎11-17-2012

Terrence,

what are you trying to accomplish?

I was able to set this up by giving interface g2/0 on the router an ip address of 1.1.1.1 255.0.0.0. This creates the logical link between the router and switch. Make sure it is up and up. Then, create the trunk between the router and the switch using g2/1on the router - allowing the vlans that you want to traverse the trunk to the switch - of course you need to create the layer 3 vlan interfaces on the router with the addresses. Then, create a trunk on g0/25 of the switch module. This will connect to the trunk you created on the router. Create the VLANs on the switch and allow them on the trunk and you should be all set. The logical interface threw me off for a while but I guess you need to do it to make the connection between the router and switch.

HTH, Pat.

tg74b2000 · ‎11-17-2012

Pat,

The way I have had a 3825 with switch module set up for the last couple of years is with sub-interfaces on the router and a trunk port on the switch module. I want to keep this same set up, if possible, for the 2951 just for the ease for my outlying personnel already doing things this way. I can use port G2/1 as a trunk port on the 2951, create the required VLANs on the 2951, and configure port G0/25 as a trunk on the switch module and pass traffic. Also, there is an address on G2/0 so I can session into the switch module.

What is causing me heartburn is the fact the I can't do sub-interfaces on G2/0 on the 295, have port G0/26 set as a trunk port, and get data moving. Like I said above, a 3825 that is being replaced by the 2951 has a switch module and I use sub-interfaces just fine. It's not really detrimental that I have to use VLANs on the 2951, it's just not making sense to me that I can't sub-interface.

V/r,

Terrence

Patrick McHenry · ‎11-18-2012

Terrence,

I believe that it is just not supported on the 2951 - I tried to set it up with sub interfaces when I started working with it but, with no luck. I like to keep things standard as well but, what can you do.

I also put a 4G card in the thing for backup WAN link. It works great when the Primary Internet goes down.

Good luck.

tg74b2000 · ‎11-20-2012

Pat,

Good news - I was able to create sub-interfaces on the 2951 G2/0. After trunking G0/26 on the switch module, I could get traffic to pass. I guess I was being too IA minded by changing the native VLAN on the router interface. It appears that is the issue. If you create a sub-interface on the router and set it as the native VLAN, traffic does not pass.

Side note... Even with setting another VLAN as native on the trunk port on the switch module, as long as you do not create the sub-interface on the router and set it native, traffic passes. I would expect to see a native VLAN mismatch error, but so far I am not. Not sure what is happening here. May be an IOS glitch.

V/r,

Terrence

Patrick McHenry · ‎11-24-2012

Terrance,

how were you able to dreate the sub interfaces? The commands weren't supported on my 2951. I tried - if you look above I posted some config. Did I have the syntax wrong?

Thanks, Pat.

tg74b2000 · ‎11-26-2012

Pat,

Below is a snippet of what I set up on the 2951. As for the switch module, I just made port G0/26 a trunk port with a native vlan 2. Also, G2/0 is the layer 3 interface you need to create sub-interfaces on due to G2/1 being a layer 2 interface which cannot have sub-interfaces.

!

interface GigabitEthernet2/0

ip add 10.10.10.1 255.255.255.254

!

interface GigabitEthernet2/0.2

encapsulation dot1Q 2 native

no ip address

!

interface GigabitEthernet2/0.10

encapsulation dot1Q 10

ip address 192.168.10.254 255.255.255.0

!

interface GigabitEthernet2/0.20

encapsulation dot1Q 20

ip address 192.168.20.254 255.255.255.0

!

interface GigabitEthernet2/1

no ip address

shutdown

!

interface vlan 1

no ip address

shutdown