SDN Internet Router (sir)

Thu Jan 5 14:57:28 UTC 2023

"The right tool for the job" gets into a religious argument in assuming that one's way to do the job is the only reasonable way to do the job. 

Large networks historically have a very poor (IMO) model of gigantic iron in a few locations, which results in sub-optimal routing for the rest of their network between those large POPs. I've heard time and time again that someone buying service from a major network in say New Orleans has a first hop of Dallas or Atlanta. I agree that full-route capable routers need to be in the large, central locations, but it isn't cost effective to have them at every POP, especially if you're a last-mile provider. 

I'd go into more examples of where it doesn't make sense to have full-route routers everywhere, but I'm afraid that the Internet would then focus on the examples instead of the core idea of intelligently putting routes into the FIBs of low-FIB routers throughout my network. 

----- 
Mike Hammett 
Intelligent Computing Solutions 

Midwest Internet Exchange 

The Brothers WISP 

----- Original Message -----

From: "Tom Beecher" <beecher at beecher.cc> 
To: "Mike Hammett" <nanog at ics-il.net> 
Cc: "Mel Beckman" <mel at beckman.org>, "NANOG" <nanog at nanog.org> 
Sent: Wednesday, January 4, 2023 7:36:58 AM 
Subject: Re: SDN Internet Router (sir) 

Disagree that it’s a line in the sand. It’s use the right tool for the job. 

If a device is low FIB, it’s that way for a reason. There are plenty of ways to massage that with policy and software, depending on capabilities , but at the end of the day, trying to sort 10 pounds of shit to store in a 5 pound bag is eventually going to end up the same way. 

On Tue, Jan 3, 2023 at 13:18 Mike Hammett < nanog at ics-il.net > wrote: 

There are likely more networks with 10 gigabit or less total external capacity than there are with more. 

Creating imaginary lines in the sand doesn't really help anyone. 

----- 
Mike Hammett 
Intelligent Computing Solutions 

Midwest Internet Exchange 

The Brothers WISP 

From: "Mel Beckman" < mel at beckman.org > 
To: "Mike Hammett" < nanog at ics-il.net > 
Cc: "NANOG" < nanog at nanog.org > 
Sent: Tuesday, January 3, 2023 10:57:34 AM 
Subject: Re: SDN Internet Router (sir) 

It’s not a problem, due to cheap, plentiful high-speed memory and rapid prefix search silicon in backbone routers. The entire Internet routing table consumes at most a few gigabytes when fully structured (and only a few hundred Mbytes stored flat). That’s less memory than your average laptop sports. 

Even in the worst case scenario, where every network decides to announce only its most specific prefixes, the BGP backbone would temporarily enter an oscillating state that generates a large number of routing updates into the inter-domain routing space. In this case, BGP route damping will quickly suppress the crazies while the backbone stabilizes. 

Small routers should not be taking full tables, since there is no point to them being in the default free zone. For large routers, neither memory nor CPU speed are an issue. High-speed routers operating in the default-free zone have a critical path in the forwarding decision for each packet: it needs to take less than the inter-packet arrival time for minimum-sized IP packets. 

This is easy to achieve with today’s hardware. A router line card with an aggregate line rate across all of its point-to-point interfaces of 10Tbps (readily available in today’s gear) can process packets with just a handful of cycles in the FIB Ternary Content Addressable Memory (TCAM) using ASIC-assisted lookups. TCAM is the most expensive component you’re paying for in such a router. It’s not cheap, but backbone routers don’t need to be cheap. They just need to not be memory-constrained. 

-mel via cell 

<blockquote>
On Jan 3, 2023, at 7:47 AM, Mike Hammett < nanog at ics-il.net > wrote: 

<blockquote>

https://github.com/dbarrosop/sir 

I came across this over the weekend. Given that the project was abandoned six years ago, are there any other efforts with a similar goal (more intelligently placing routes into FIBs of low-FIB capacity devices? 

----- 
Mike Hammett 
Intelligent Computing Solutions 

Midwest Internet Exchange 

The Brothers WISP 

</blockquote>

</blockquote>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.nanog.org/pipermail/nanog/attachments/20230105/7e2fd14c/attachment.html>