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New Member

Routing between 3945 + Integrated switch module

Hi Experts,

I've a 3945 with SM-ES3G-24-P module installed and tried to configure some routing but it doesnt work..

1. L3 interface on the switch modules (with ip address configured)

2. OPSF on the router with connected interface redistribute (which includes the switch module L3 interfaces)

I dont see any of the switch module L3 interfaces routes in the router, not even the connected interface..

Anything i did wrong ??



int g0/1

  no switchport

  ip add



int g0/0

ip add

router ospf 1

redistribute connected

network area 0


Everyone's tags (1)
VIP Super Bronze

Routing between 3945 + Integrated switch module


From the router can you ping the switch or vice versa?

New Member

Routing between 3945 + Integrated switch module

Nope, i cant ping to the switch (one of the L3 interface), in this case G0/1 (

VIP Super Bronze

Routing between 3945 + Integrated switch module

Ok, so you have a layer-3 interface on the switch with an IP of also need to have the same subnet with a different host address on the router example  what interface on the router is the same subnet as the switch?  Can you provide "sh ip int bri" from the router and the switch?


New Member

Re: Routing between 3945 + Integrated switch module

Erm, means i need to have a physical interface on the router with the same subnet of the switch module interface ? Or it can be subinterface ? and if can be subinterface, which physical interface should i use ? Is there any doco on this ?

I cant really create an IP for the same subnet in the router interface, as the L3 interface subnet is /30, which is being used already.. and we cant really change the subnet at this trying to find a way for the routing to work via the backplane between the switch n router, but couldnt find anything...if we have to create another IP in the router for each L3 interface in the switch module, it will be wasting one IP address for each subnet..and some of the L3 interface on the switch module, we are using /30 and obviously, no additional ip add available.

will be good if there's a way to router via the backplane (G0/25 & G0/26 on the switch module) to the router..

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