[c-nsp] Router recommendation

[Robert E. Seastrom]

Rick Kunkel <kunkel at w-link.net> writes:

> I'll do my best for current stuff.  Need a little room to grow too I 
> suppose...
>
>> How many customers (ie, how many pppoe/lt2p sessions)?
>
> Actually, none of pppoe or l2tp right now.  We've got about 350 DSL 
> customers that are currently running in the "atm route-bridged ip" mode.  
> At some point, we may switch these to ppp.  It's also possible that we may 
> move another DSL aggregation circuit we have from Verizon into this 
> router, which would add about another 350.  Also, I suppose we could do 
> some point-to-point links from this router at some point.

Fine so far...

>> How many packets/second?
>
> This, unfortunately I do not have a great handle on.

This is the #1 thing that you need to be concerned about,
unfortunately.  Cost to switch a small packet and a big packet are
roughly the same.

>> How many megabits/second?
>
> We anticipating around 1 Gbps, but I think we better plan on a few times 
> that.

Well, by my numbers, 1 Gbps would suggest roughly 12000 customers
simultaneously online at peak, which probably means 16-17k customers
on the books.  That would represent some pretty impressive growth;
you've got 700 customers now - sustained +150% year over year
(i.e. your population a year from now is 2.50x your current
population) would not get you there in 3 years.  Ask your marketing
and sales folks if they honestly (ha!) think they can pull that off
and sustain it for 4 years.  This is all of course assuming that
you're not trying to do IPTV or something similar over wholesale
circuits (which is why we're talking about PPPoE in the first place),
right?  My experience is that unless you control the network all the
way to the edge (for instance, vdsl in buildings and fiber to the
basement), you'll find that the business model doesn't work.

Hopefully somewhere along this timeline you're getting capex to
upgrade to multiple boxes and scale horizontally - that was one of my
first goals and the big reason we were on NPE300s for so long - I
wanted to have some nice horizontal scaling with ability to move
customers to spare capacity on an intentionally lightly loaded box if
one of my edge routers croaked.  The call center director appreciates
your efforts to keep outages short even if they statistically happen a
little more frequently.  :-)

Oh yeah, one other thing while we're on the topic of single box...
have you talked with the appropriate folks about getting an OC48 or
gige or some other kind of suitable handoff for this traffic?  My
experience has been that the LEC is usually pretty far behind the
curve when it comes to pipe size.

> And of course i already mentioned that it probably needs to safely hold 3
> full routing tables.

To clarify (yes, I did miss that because it fell off the beginning of
the discussion) you mean three views, not three RIBs in some sort of
VRF-based jack move, right?

One last thing, yes, I know this is cisco-nsp, but were I in your
shoes I would be checking out the Juniper ERX series too.  Unlike the
6500 (and the GSR, which as other have noted doesn't even have the
feature set), the ERX is specifically designed for this application.

                                        ---Rob