[c-nsp] LNS question asr 1002

[Arie Vayner (avayner)]

Actually, there is a solution for that... It's called ODAP and it allows your LNS to pull address pools from a server.
So you can have smaller pools (like /25's or /24's) assigned from the server and announced as aggregates.
Even a /25 is better than 128x/32's

http://www.cisco.com/c/en/us/td/docs/ios/ios_xe/ipaddr/configuration/guide/xe_3s/iad_xe_3s_book/iad_dhcp_sod_apm_xe.html

It has been a while since I played with it, but the concept should be mostly the same.

Arie

-----Original Message-----
From: Youssef Bengelloun-Zahr [mailto:youssef at 720.fr] 
Sent: Monday, August 18, 2014 10:17
To: Arie Vayner (avayner)
Cc: Mike; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] LNS question asr 1002

Hello Arie,

I hear you and your arguments are perfectly understandable. The only downside I see with per-LNS pool is lack of redundancy in case of hardware failure.

In previous companies I worked for, PPPoL2TP used to terminate randomly on a pool of LNS based on a radius Round Robin algorithm. Excellent for balancing sessions evenly (or not) but the one downside is that you have to re-announce /32s inside your BGP domain. If you RRs can handle it, then why not do it...

I guess that this isn't a problem for small to medium sized ISPs, but that's a different song for big ones.

Again, it'll all depends on your business case and pre-requisits.

Best regards.



> Le 18 août 2014 à 18:50, "Arie Vayner (avayner)" <avayner at cisco.com> a écrit :
> 
> You may actually want to look at summarizing this. The best practice would be to have a per-LNS pool (either locally managed or from RADIUS) and advertise the summary from the LNS up to the network.
> You may need to redistribute also connected routes for "fixed IP" services where a user may have a custom IP from the RADIUS.
> 
> Not summarizing means that every connection (and disconnection) is a BGP update driving your CPU utilization across the BGP domain...
> 
> 
> Arie
> 
> -----Original Message-----
> From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf 
> Of Mike
> Sent: Monday, August 18, 2014 09:23
> To: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] LNS question asr 1002
> 
> 
>> On 08/17/2014 08:24 PM, Edwardo Garcia wrote:
>> Secondly, how does one handle running two LNS servers? How does the 
>> border router know which edge (LNS) to forward too for a particular 
>> IP?
> 
>     I do it with iBGP where my router is advertising individual /32's. 
> Yes it makes the route tables longer but it works well in my environment. YMMV.
> 
> Mike-
> 
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