Re: [Lsr] Why only a congestion-avoidance algorithm on the sender isn't enough Mon, 04 May 2020 06:12 UTC

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Subject: Re: [Lsr] Why only a congestion-avoidance algorithm on the sender isn't enough
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> 			I think we/you are looking at two different problems: 1) a hop count of 1 or maybe two between the two end points 2) and the multiple / many hop count between the two end points.

IS-IS adjacencies are always between immediate L3 neighbors, ignoring strange things like tunneling.

> 			Thus, I think that your issue is mostly the #2 problem and the problem that most CA algorithms IMO always try to increase capacity and thus at some point must exceed capacity. TCP must find a range of capacity per flow (assuming a consistent a number of packets per sec). However, what is maybe missed (I missed it in the document) is the ability not to overshoot the TCP threshold point and trigger multiple initial congestion events in/exiting the slow-start phase.

Modern router designs have interface bandwidths from 10-400Gb/s.  The CPU would be hard pressed to supply 1Gb/s, therefore for most of the circumstances that we’re concerned about, the link capacity is never the issue.