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TimGuyUK
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Joined: Fri Jul 29, 2016 11:36 am

UK Lease line WAN subnet mask on MK routers

Wed Oct 10, 2018 5:17 pm

Hi

Dealing with UK lease line WAN circuit suppliers (well BT and Virgin) I always have to program the WAN interface of the MK with a mask of at least /29 (and sometimes /28) where as the documented subnet mask from the supplier is always 255.255.255.254 (/31). The Aggregation router is always the next ip up. CPE IP x.x.x.246 and AR IP x.x.x.x.247 yet I can only ever bring up the route if I use /29 (/28) as the network mask.

Anyone else have this issue? Its never been a problem because Ive never had a customer with two circuits in the same location at the same time but one day Im going to hit a hurdle of having another circuit on say .248 (in the above example) and Im not going to be able to route to it.

Tim
 
mkx
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Re: UK Lease line WAN subnet mask on MK routers

Wed Oct 10, 2018 5:30 pm

I seem to remember a thread or two on this forum where users complained about MT not allowing /31 netmask (if you think of it, it doesn't seem like valid netmask as it lacks network and broadcast addresses). But there's a workaround (from the first linked thread):
/ip address
add address=1.2.3.246/32 network=1.2.3.247 interface=ether1
i.e. set CPE IP as its address with 32-bit netmask and set AR's IP address as network address.

I certainly hope the right guy will come by and correct my mistakes ...
BR,
Metod
 
TimGuyUK
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Posts: 24
Joined: Fri Jul 29, 2016 11:36 am

Re: UK Lease line WAN subnet mask on MK routers

Wed Oct 10, 2018 5:48 pm

I seem to remember a thread or two on this forum where users complained about MT not allowing /31 netmask (if you think of it, it doesn't seem like valid netmask as it lacks network and broadcast addresses). But there's a workaround (from the first linked thread):
/ip address
add address=1.2.3.246/32 network=1.2.3.247 interface=ether1
i.e. set CPE IP as its address with 32-bit netmask and set AR's IP address as network address.

I certainly hope the right guy will come by and correct my mistakes ...
Thats got it. Nice one. Apprecaite it and seams obvious when you look at the solution.

Thanks again

Tim

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