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3745 router with 36-port power enabled Ethernet Module Issues

Unanswered Question

have a 3745 with the 36-port Ethernet module in it to provide inline power and connectivity for IP phones. I am having trouble getting everything to play nicely, specifically inter-VLAN routing and DHCP on the 3745.

If I setup the router with sub-interfaces (int fa0/0.55, etc.) like you would do on an external router, I can get inter-VLAN routing between the router, a switch and another router in my test network, but my IPphones and clients can't get DHCP from the switch module or communicate at all.

If I setup the router with VLAN interfaces (int VLAN 55, etc.) like you would do on a switch or RSM, I can get inter-VLAN routing on the devices (IP phones, laptop) connected to the 36 port module, but I can't ping the switch, router, etc. (anything not connected to the 36-port module).

And obviously you can't do both (sub-interfaces and VLAN interfaces).

I have a setup already with a 3745 where we're not using the 36-port module, and the phones plug directly into a 3524-PWR-XL switch and we trunk between the switch (using int VLAN 55, etc.) and the router (sub-interfaces), and everything works fine, since the logic is on two seperate devices. But when I go to put everything on the 3745, I can only get one or the other.

I found a forum article mentioning an upgrade to the IOS. I am currently running c3745-is-mz.122-8.T5.bin. I downloaded c3745-js-mz.122-13.T.bin but when I go to install it is says that there's not enough room on the device. Shouldn't is prompt me to erase then continue?

Any ideas on this??

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After a lot of research, I figured it out...

Can't do sub-interfaces (Layer 3) on FA0/0 or FA0/1 with the ESW, it needs layer 2, and you can't trunk on FA0/0 or FA0/1. So you need to use "Int VLAN YY" instead of sub-interfaces to get your clients on the ESW to be able to do inter-VLAN routing.

This still leaves one issue......how do I trunk the VLANs to an upstream device (mine is a 2950) if FA0/0 or FA0/1 don't do trunking (Layer 2)??? Plug a cross-over from your uplink on upstream switch to a port on the ESW. That one took me a long time to figure out, but it's Friday.



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