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Scorpio1971
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cisco 897 WAN side Vlan config

Hi

based on my recent success with silly questions I thought I'd try again.

I have Wires only line for an ISP, details :-

a.b.c.1/30 as the remote gateway

a.b.c.2 as my "outside" router address
Vlan 10

I have routed subnet on a /29, which is fine, I just need to get a.b.c.2 on Vlan 10 so I can route into a.b.c.1.

I am using a 897 with the ISP line on gi8 as the handoff is MM fibre and gi8 has sfp.


I've tried various things but I just can't get to the point I can ping a.b.c.1, I am blatantly missing something here so any abuse accepted!


Thank you




Cisco

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Craig Beck

8/22/2022 - Mon
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Craig Beck

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Scorpio1971

ASKER
Hi

couldn't agree more, I have never had a vlan on a /30 or /31 route before but the carrier (bt I think) uses it.

You have highlighted exactly what I have tried, I can't ping their gateway, my inside ports are one vlan and routed fine, I just can't open the link to the remote gateway.

I had got as far as a "sub interface" , but how does gi8.10 connect to physical gi8? Are they effectively linked?

Thanks for you comments
Scorpio1971

ASKER
OK, 2nd try, the sub int was the solution, just after the ISP sorted out their end!

thank you!
Craig Beck

I had got as far as a "sub interface" , but how does gi8.10 connect to physical gi8? Are they effectively linked?
Yes, a subinterface is just a virtual interface connected to the physical interface, so it's physical port 8, virtual interface 10.

BT use a lot of different configurations depending on the circuit type, IP provision, etc. It's common to be given a /30 for the WAN if you have been given an additional routed subnet.

Glad you got it working!
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