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bairdmj

join:2009-12-30
reply to unwired9

Re: [Tech Ops] MPLS

If you centrally assign IP addresses via RADIUS (from one common, central pool), you will inject one host route (a /32) into your IGP's (OSPF) routing table for every client who connects. Furthermore, every time one of your clients disconnects/reconnects their PPPoE connection, an update to your routing table will occur. Each device that participates in OSPF on your network will will receive the "update" every time a PPPoE connection state changes.

If you choose to route a block of IPs to each PPPoE concentrator, it will be a bit more difficult to manage your IPs efficiently. But, you will be able to summarize the route for the block of IPs. This means that instead of having 253 /32 host-routes for each client in a /24, the router/concentrator would only announce one summary route (the /24) to the rest of your network. In addition, because you are summarizing the route, your routing table won't update each time a client connects/disconnects.



Inssomniak
The Glitch
Premium
join:2005-04-06
Cayuga, ON
kudos:2

said by bairdmj:

If you centrally assign IP addresses via RADIUS (from one common, central pool), you will inject one host route (a /32) into your IGP's (OSPF) routing table for every client who connects. Furthermore, every time one of your clients disconnects/reconnects their PPPoE connection, an update to your routing table will occur. Each device that participates in OSPF on your network will will receive the "update" every time a PPPoE connection state changes.

You can still filter this out no problem. I have a centrally assigned IP address setup from RADIUS and just block it in an "ospf-out" chain so all my other routers cant see it, they have no need to see it.
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TomS_
Git-r-done
Premium,MVM
join:2002-07-19
London, UK
kudos:5

Yeah. Most likely you can have the router doing the termination announce a summary route in place of all of the host routes.

If youre terminating locally at each tower or in a non-centralised way, naturally you have little choice.