[c-nsp] Router for wholesale DSL aggregation over L2TP

[Tony]

Hi Scott,

The number of sessions isn't totally relevant, more important is the bandwidth through the router. We had an old NPE-300 terminating LT2P sessions and it coped quite easily with 200-250 DSL users but they were low speed (mostly 512k or 1500k), so throughput was only about 20-30Mbps in total (from memory CPU was about the same number, ie. 20-30%)

Work out if a 3845 has enough grunt to route the traffic you need and then you can decide based on that. If you're buying 2nd hand then I would think a better option might be a 7204 with NPE-G1 in it for around the same coin (and is the same thing everyone else is using).

As mentioned by someone else you will need larger MTU to handle the overhead (ie. need GigE with jumbo) and need to make sure that the handoff from your carrier allows for this too.


regards,
Tony.





>________________________________
> From: Scott Lambert <lambert at lambertfam.org>
>To: cisco-nsp <cisco-nsp at puck.nether.net> 
>Sent: Thursday, 17 January 2013 4:28 AM
>Subject: [c-nsp] Router for wholesale DSL aggregation over L2TP
> 
>Windstream is changing us over from our ATM DS3 to ethernet handoff
>for DSL aggregation.
>
>We are looking to get a different router to take the ethernet handoff
>in another location.  Our current router is a 7204VXR with NPE-G1.  
>
>I've been looking at what might be available inexpensively.  It
>looks like a 3845 is specified to handle 1200 or so L2TP connections.
>We have around 800 DSL subscribers.  We can add more subscribers
>after we get the additional bandwidth available on the ethernet
>handoff.  But we don't expect to grow the DSL side of the business
>very much.  We are mostly focused on fixed point wireless at this
>point.  I believe we will only need 50 to 100Mbps of Internet,
>no dynamic routing protocols.
>
>For less than $1000, there are 3845s available on eBay.   If the
>3845 will do the trick, I can get a spare.  
>
>The 3945 is around $5000 - $7000 on eBay.  That's not what we call
>inexpensive.  It's tough being a small independent ISP.  I just
>haven't been able to google up the rated L2TP specs for the 3900
>series.
>
>Am I even looking at the correct range of hardware for our wholesale
>DSL aggregation?
>
>We have not done the L2TP handoff before.  Do I need to be careful
>to make sure the software is licensed for a particular feature set?
>
>Should I just do it on my 7204VXR?  We could afford to call a
>maintenance window for the hour or two necessary to transport it
>to the new location if needed.  Everything would need to go perfectly
>and that never happens... :-)
>
>-- 
>Scott Lambert                    KC5MLE                       Unix SysAdmin
>lambert at lambertfam.org
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