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Community Member

Config Help

Hi

I have 3825 with 24 port EtherSwitch Module. I want to configure multiple VLANs on the system and route between them. How?

Router has Adv Sec IOS, switch module has IP Base IOS.

Also can router act as VTP server for switch?

6 REPLIES

Re: Config Help

Community Member

Re: Config Help

Hi

That looked good, but the 24 port module is not seen by the router. I have to configure it via a "service-module" command.

Also, I have to give int Gi2/0 an IP address before I can open a session to the switch module. Where is Gi2/0? Is it an internal int?

Somewhere there must be a config document that can put me on the right track.

I can config the router OK. I can config a switch OK. But the mix of 3825 and Etherswitch has got me scratching my head a bit.

Someone MUST have done this before.

Ian

Community Member

Re: Config Help

After working through this issue myself I have come to a few conclusions.

1. Cisco did not intend for this switch module to be used with a layer 2 link to the router.

2. You can't configure a trunk encapsulation on the g2/0 interface and subinterfaces don't play well with others.

3. The g2/0 interface corresponds to the slot the NME is in.

You can enable layer 3 connectivity between your switch module and the g2/0 interface. Simply place an IP address on the vlan 1 interface of the switch module that is in the same subnet as your g2/0 interface. This will enable you to ping back and forth. If you have the EMI image on your switch module you can then add routed interfaces or other vlan interfaces (through vlan database) and route these subnets on the switch module and subsequently through your vlan 1 layer 3 connection to the 3825. I myself had been trying to determine how I could build sub interfaces off of g2/0 and trunk the vlans but I don't think that was the intent of this architecture. I learned this through much pain and suffering. If someone can prove me wrong I'm all ears but at least this way works.

Hope that helps.

Rick

Community Member

Re: Config Help

Ok

So, lets see what I CAN do.

The router chassis will be connected to my WAN using OSPF. No problems there.

Give Gi2/0 an IP address in VLAN 1 of switch module, also add that to OSPF in router, then any device on WAN can ping VLAN 1 of switch module.

I have IP base on switch module so seems I need to get EMI for this module to make routing between multiple VLANs to work. Now, is there an EMI for this module?

All I need are four VLANs (on the switch module)that the WAN can see, wish subinterfaces on Gi2/0 would do the trick! Apart from VLAN 1 traffic the other VLANs are only to be used in a disaster situation, if ever.

Community Member

Re: Config Help

There is an EMI image for the NME Module. If you reguire OSPF then you must get the IP Services or ADV IP services. Try searching for "c3750-advipservices-mz.122-25.SEE"

The IP base EMI doesn't support most of the routing protocols but does support routing. If you can't obtain the advipservices image you could do it with static routes.

With the advipservices image your configuration would look something like this.

ip routing

interface Vlan1

ip address

no ip route-cache

!

interface Vlan6

ip address

no ip route-cache

!

interface Vlan7

ip address

no ip route-cache

!

interface Vlan69

ip address

no ip route-cache

router ospf xx

network vlan 1

network vlan 6

network vlan 7

network vlan 69

!

ip default-gateway ip address to g2/0

ip classless

This will allow the NME to neighbor with the 3825 (via Vlan1) and then OSPF will take care of the rest. Remember the routes to the vlans will only show up if there is a port in an up up state to cause the vlan itself to come up.

Hope this helps.

Rick

Community Member

Re: Config Help

Thanks for that. No budget to get EMI for switch module but have come up with a work round.

Create all VLANs as per your config. Then, when I require these VLANs to work I can add static route in router config and redistribute into the OSPF.

Simple. As this is a disaster recovery router, a little manual input is allowed.

Many thanks for your help, much appreciated.

Ian

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