nanog mailing list archives
Re: Scalability issues in the Internet routing system
From: Blaine Christian <blaine () blaines net>
Date: Wed, 26 Oct 2005 13:18:55 -0400
On Oct 26, 2005, at 12:12 PM, Valdis.Kletnieks () vt edu wrote:
On Wed, 26 Oct 2005 08:53:50 PDT, Alexei Roudnev said:Anyway, as I said - it is only small, minor engineering question - how to forward having 2,000,000 routes. If internet will require such router - it will be crearted easily. Today we eed 160,000 routes - and it works (linecards,m software, etc - it DO WORK).Forwarding packets is only half the story. Building a routing table isthe other half.Route flaps. Even if you have an algorithm that's O(n), 2M routes will take 12.5 times as long to crunch as 160K. If your routing protocol is O (n**2) onnumber of routes, that's about 150 times as much.Such a router is probably buildable. I'm not at all convinced that it's "easy" to do so at a price point acceptable for most sites that currently have fullrouting tables.
There are definitely performance challenges to overcome. Of course, most route processors are underpowered compared to the existing state of the art for processors so there is some wiggle room.
With both Cisco and Juniper we have a nice period of hang time as "brand new" new routes get installed. Both vendors are playing with layers of abstraction to improve things once up and operational but increasing the amount of time to bring a device "online" is factor which influences purchasing decisions as well.
It does seem appropriate to consider Gigabit sized routing/forwarding table interconnects and working on TCP performance optimization for BGP specifically, if any improvement remains. Combine those things with a chunky CPU and you are left with pushing data as fast as possible into the forwarding plane (need speedy ASIC table updates here).
Another thing, it would be interesting to hear of any work on breaking the "router code" into multiple threads. Being able to truly take advantage of multiple processors when receiving 2M updates would be the cats pajamas. Has anyone seen this? I suppose MBGP could be rather straightforward, as opposed to one big table, in a multi-processor implementation.
Regards, Blaine
Current thread:
- Re: Scalability issues in the Internet routing system, (continued)
- Re: Scalability issues in the Internet routing system Lincoln Dale (Oct 26)
- Re: Scalability issues in the Internet routing system Rubens Kuhl Jr. (Oct 26)
- Re: Scalability issues in the Internet routing system James (Oct 26)
- Re: Scalability issues in the Internet routing system Rubens Kuhl Jr. (Oct 26)
- Re: Scalability issues in the Internet routing system sthaug (Oct 26)
- Re: Scalability issues in the Internet routing system Elmar K. Bins (Oct 27)
- Re: Scalability issues in the Internet routing system sthaug (Oct 27)
- Re: Scalability issues in the Internet routing system JORDI PALET MARTINEZ (Oct 26)
- Re: Scalability issues in the Internet routing system Alexei Roudnev (Oct 26)
- Re: Scalability issues in the Internet routing system Valdis . Kletnieks (Oct 26)
- Re: Scalability issues in the Internet routing system Blaine Christian (Oct 26)
- Re: Scalability issues in the Internet routing system Andre Oppermann (Oct 26)
- Re: Scalability issues in the Internet routing system Christopher L. Morrow (Oct 26)
- Re: Scalability issues in the Internet routing system Blaine Christian (Oct 26)
- Re: Scalability issues in the Internet routing system Andre Oppermann (Oct 26)
- Re: Scalability issues in the Internet routing system Blaine Christian (Oct 26)
- Re: Scalability issues in the Internet routing system Andre Oppermann (Oct 27)
- Re: Scalability issues in the Internet routing system Blaine Christian (Oct 27)
- Re: Scalability issues in the Internet routing system Michael . Dillon (Oct 27)
- Re: Scalability issues in the Internet routing system william(at)elan.net (Oct 27)
- Re: Scalability issues in the Internet routing system Lincoln Dale (Oct 26)