Re: 1941/1921 router - group onboard Gig Ethernet ports with switch Gig Ethernet ports on EHWIC-4ESG

radiomean · ‎06-14-2020

Hi, I would like advice on how to group the onboard GigEthernet ports 0/0 and 0/1 with switch GigEthernet ports 0/1/0, 0/1/1, 0/1/2 and 0/1/3 on the add in EHWIC-4ESG card... (if possible).

I've setup a Vlan for and put the switch ports in it and they behave as expected - but I can't put the onboard GigEthernet ports into the same Vlan. The add in card gives me 4 ports and I would ideally like to use the onboard ports as a couple more of switch ports - but I realise the onboard ports are routed - so can I emulate switch port behaviour? I know I could use a EHWIC-D-8ESG but I feel that's inelegant - and I would like to save money and use the unused onboard ports...

A bridge virtual interface has been mentioned and I'd appreciate advice on this please - or any other solution.

Many thanks, Bill

Richard Burts · ‎06-14-2020

The Bridged Virtual Interface used with Integrated Routing and Bridging is the technique that would allow you to configure bridging on the 2 onboard ports, This makes them act more like switch ports than routed ports. But I am not sure that you would be able to put them into the same vlan as your EHWIC ports.

HTH

Rick

radiomean · ‎06-14-2020

Thanks - I've also found this doc which gives more details on IRB...

https://www.cisco.com/c/en/us/support/docs/lan-switching/integrated-routing-bridging-irb/17054-741-10.html

And there is this thread which seems to do pretty much what I want to do...

https://community.cisco.com/t5/switching/configuring-1941-with-8-port-ehwic-switch-module-and-onboard-ge/td-p/1977385

Both of these seem to be pretty much what I want so I'll have to give it a try. I wonder if there is a performance penalty though?

Thanks anyway...

radiomean · ‎06-14-2020

OK, well if anyone is interested, BVI seems to work a treat...

I've setup the onboard GiGEthernet 0/1 and the four switched ports on the EHWIC-4ESG together in a VLAN and they all seem to see and talk to each other, get an IP address from DHCP etc. I have put one laptop on the onboard port and two others on the switch ports and it still seems to work, so all that is really needed to do is connect to a WAN and see if the speed is what I expect... ie is there a performance hit?

Cheers all...

Richard Burts · ‎06-15-2020

Thanks for the update. It is good to know that you have implemented this and that it does seem to work. I had been concerned whether the router would allow the IP assigned for the BVI to be in the same subnet (same vlan) as the ESG ports. Apparently that is not an issue. Is there an SVI for the vlan for the ESG ports? Do the devices connected on ESG ports have the same default gateway as the devices connected to the on board ports? What is their default gateway?

HTH

Rick

radiomean · ‎06-15-2020

I simply assigned an IP address to BVI178 (178 is the number I used!).

I put one of the onboard gigethernet ports in bridge group 178

I then put the four EHWIC-4ESG ports into vlan 178, and put vlan 178 into bridge group 178 (with no ip).

That seemed to do the trick...

(I'm a bit of a novice, excuse me if I don't answer your question fully!)

All the best...

radiomean · ‎06-15-2020

Regarding the IP address, neither the onboard gigethernet port nor the vlan are assigned ip addresses - they are both put into the bridge group, and only the bridge group interface bviXXX is assigned an IP address...