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Re: SDN Internet Router (sir)

From: Joe Maimon <jmaimon () jmaimon com>
Date: Thu, 5 Jan 2023 15:22:22 -0500
Lots of 1M tcam fib limits in older gear.......
So yeah, its the same problem, bigger numbers and still not solved in any sort of non-painful or expensive way. 

I think Ill explore the google path and paper on it again.

Joe

Mike Hammett wrote:

Then please bless the world with the right way.
You acknowledge that not every router in a network needs to be fully DFZ capable, but then crap on my desire to have more than a default route in one. 



-----
Mike Hammett
Intelligent Computing Solutions <http://www.ics-il.com/>
<https://www.facebook.com/ICSIL><https://plus.google.com/+IntelligentComputingSolutionsDeKalb><https://www.linkedin.com/company/intelligent-computing-solutions><https://twitter.com/ICSIL>
Midwest Internet Exchange <http://www.midwest-ix.com/>
<https://www.facebook.com/mdwestix><https://www.linkedin.com/company/midwest-internet-exchange><https://twitter.com/mdwestix>
The Brothers WISP <http://www.thebrotherswisp.com/>
<https://www.facebook.com/thebrotherswisp><https://www.youtube.com/channel/UCXSdfxQv7SpoRQYNyLwntZg>
------------------------------------------------------------------------
*From: *"Tom Beecher" <beecher () beecher cc>
*To: *"Mike Hammett" <nanog () ics-il net>
*Cc: *"Mel Beckman" <mel () beckman org>, "NANOG" <nanog () nanog org>
*Sent: *Thursday, January 5, 2023 9:55:38 AM
*Subject: *Re: SDN Internet Router (sir)

    "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
I disagree that it's religious. I completely agree there are locations in networks that having full DFZ capable routers doesn't make technical or economic sense. But there have long been different products for those different use cases.
To perhaps explain my viewpoint better,(and perhaps I didn't properly comprehend the problem you're aiming to solve) :
If you are trying to use SDN stuff to shuffle routes on and off a box because you have the wrong sized routers in place, then I would argue you're doing it wrong.
If you are trying to use SDN stuff to (as Christopher mentioned) make decisions that are not strictly LPM, and the equipment you have cannot do that, then that's different and entirely reasonable.
If the second use case is more of what you were asking, then I apologize for misunderstanding.
On Thu, Jan 5, 2023 at 9:57 AM Mike Hammett <nanog () ics-il net <mailto:nanog () ics-il net>> wrote: 

    "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 <http://www.ics-il.com/>
    
<https://www.facebook.com/ICSIL><https://plus.google.com/+IntelligentComputingSolutionsDeKalb><https://www.linkedin.com/company/intelligent-computing-solutions><https://twitter.com/ICSIL>
    Midwest Internet Exchange <http://www.midwest-ix.com/>
    
<https://www.facebook.com/mdwestix><https://www.linkedin.com/company/midwest-internet-exchange><https://twitter.com/mdwestix>
    The Brothers WISP <http://www.thebrotherswisp.com/>
    <https://www.facebook.com/thebrotherswisp><https://www.youtube.com/channel/UCXSdfxQv7SpoRQYNyLwntZg>
    ------------------------------------------------------------------------
    *From: *"Tom Beecher" <beecher () beecher cc <mailto:beecher () beecher cc>>
    *To: *"Mike Hammett" <nanog () ics-il net <mailto:nanog () ics-il net>>
    *Cc: *"Mel Beckman" <mel () beckman org <mailto:mel () beckman org>>,
    "NANOG" <nanog () nanog org <mailto:nanog () 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 () ics-il net
    <mailto:nanog () 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 <http://www.ics-il.com/>
        
<https://www.facebook.com/ICSIL><https://plus.google.com/+IntelligentComputingSolutionsDeKalb><https://www.linkedin.com/company/intelligent-computing-solutions><https://twitter.com/ICSIL>
        Midwest Internet Exchange <http://www.midwest-ix.com/>
        
<https://www.facebook.com/mdwestix><https://www.linkedin.com/company/midwest-internet-exchange><https://twitter.com/mdwestix>
        The Brothers WISP <http://www.thebrotherswisp.com/>
        <https://www.facebook.com/thebrotherswisp><https://www.youtube.com/channel/UCXSdfxQv7SpoRQYNyLwntZg>
        ------------------------------------------------------------------------
        *From: *"Mel Beckman" <mel () beckman org <mailto:mel () beckman org>>
        *To: *"Mike Hammett" <nanog () ics-il net <mailto:nanog () ics-il net>>
        *Cc: *"NANOG" <nanog () nanog org <mailto:nanog () 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

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

            
            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 <http://www.ics-il.com/>
            
<https://www.facebook.com/ICSIL><https://plus.google.com/+IntelligentComputingSolutionsDeKalb><https://www.linkedin.com/company/intelligent-computing-solutions><https://twitter.com/ICSIL>
            Midwest Internet Exchange <http://www.midwest-ix.com/>
            
<https://www.facebook.com/mdwestix><https://www.linkedin.com/company/midwest-internet-exchange><https://twitter.com/mdwestix>
            The Brothers WISP <http://www.thebrotherswisp.com/>
            <https://www.facebook.com/thebrotherswisp><https://www.youtube.com/channel/UCXSdfxQv7SpoRQYNyLwntZg>
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