ASR BNG + standard routing + cache?

[puddingtech]

Just wondering, if we go with the ASR9001-s for a BNG setup, is it possible to setup the units to also handle the general service routing. Let me explain

Port 1 = connectivity to internet

Port 2 = Customer vlans for BNG

Port 3 (MPA) = Alternative network only to be routed to the internet not processed by BNG

Port 4 (MPA) = Connectivity to cache server to cache http traffic

I don't see any issue with this from what I've read as the ISG listener is port based, so it won't touch the port 3 traffic, and we can route it normally right?

Now i saw that WCCP isn't supported in ASR? Does that mean we can't do it this way and we'd have to add another box in between the Internet and ASR9k

[xthuijs]

you can use this design indeed, there is no functional restriction between the onboard and MPA based ports as such so from that standpoint no issue.

there is indeed no WCCP and not planned, but if you want to achieve something similar could leverage ABF (acl based forwarding) or PBR (policy based routing) to direct traffic from an ingress source to a designated nexthop or interface.

ABF can work with redundant next hops and if you split the subnet out that needs to be redirected into say 2x /25's and each ACE would then say nexthop1 nexthop2 and the other one nexthop2 nexthop1 so they are backup of each other and you can loadbalance some of the traffic that way?

cheers!

xander

[puddingtech]

about what i expected... silly question but is their a reason why you guys decided to drop WCCP support?

So in your example above we could do the ABF to forward port 80 to the cache, with a next hop as the standard default gateway in the event the cache was to crash and no redundant cache was available...

What exactly are we loosing in this kind of setup vs the old wccp setup if you don't mind me asking? 

[xthuijs · Accepted solution]

fair question and the honest answer is there that so far it has not been "worth the development effort". looking at WCCP and what it does, and the a9k having the capability of ABF or HTTP redirect appeared to be accomodating in all the scenarios where it had come up, hence it hasnt become a priority.

wccp has the ability to encap requests in GRE allowing for multihop between the two endpoints, but then with 522 we have the ability to set the destination address in a request so we can force redirection based on that new destination ip.

ABF is more like L2-based WCCP whereby the cache and redirecting router are assumed to be on the same network or having a direct link.

yeah so you're not really losing anything of not having wccp with the tools that are there today.

cheers!

xander

[puddingtech]

Thank xander you really are a great help!