why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?)

Mark Tinka mark.tinka at seacom.mu
Sun Jun 21 08:21:35 UTC 2020

On 20/Jun/20 15:39, Masataka Ohta wrote:

> Ipsilon was hopeless because, as Yakov correctly pointed out, flow
> driven approach to automatically detect flows does not scale.
> The problem of MPLS, however, is that, it must also be flow driven,
> because detailed route information at the destination is necessary
> to prepare nested labels at the source, which costs a lot and should
> be attempted only for detected flows.

Again, I think you are talking about what RSVP should have been.


> Routing table at IPv4 backbone today needs at most 16M entries to be
> looked up by simple SRAM, which is as fast as MPLS look up, which is
> one of a reason why we should obsolete IPv6.

I'm not sure I should ask this in fear of taking this discussion way off
tangent... aaah, what the heck:

So if we can't assign hosts IPv4 anymore because it has run out, should
we obsolete IPv6 in favour of CGN? I know this works.

> Though resource reserved flows need their own routing table entries,
> they should be charged proportional to duration of the reservation,
> which can scale to afford the cost to have the entries.

RSVP failed to take off when it was designed.

Outside of capturing Netflow data (or tracking firewall state), nobody
really cares about handling flows at scale (no, I'm not talking about

Why would we want to do that in 2020 if we didn't in 2000?


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