>Spencer, yes I wasn't suggesting ECN as "the defined standard", and
>wasn't even aware of all the problems with it you mention.
Spencer is correct that the absence of ECN cannot be used as an
indication of corruption instead of congestion, even in an environment
where all flows and all routers are ECN-Capable.
First, even in such an ECN-Capable environment, it is possible to
have sufficiently high congestion that buffers overflow, forcing
a packet drop due to congestion. The use of ECN cannot *ensure*
that buffers never overflow due to transient congestion.
In addition, routers are advised to drop instead of mark packets
in times of *high* congestion, even if the buffer has not yet
overflowed. This gives the network some protection against flows
that would be inclined to lie about being ECN-Capable (or for whom
a rogue or broken router is "erasing" ECN/CE bits from packet headers
downstream in the network).
- Sally
This archive was generated by hypermail 2b29 : Mon Feb 14 2000 - 16:14:55 EST