The MPLS WG Archive

[Keith.Schuettpelz@go.ecitele.com]

Eric Gray wrote:

> Consider this.  You are about to discard a packet
> because it is to large.  Who cares if you do this on the
> slow path?

I see at least 2 issues...

1) If you need to fragment the packet rather than discard it
Doing this in the slow path can result in packet re-ordering w.r.t.
subsequent smaller packets processed in the fast path.
Is this acceptable?

2) If you need to send an ICMP message back to the source.
How fast must the slow path be in order to handle all of the
concurrent PMTUD's being performed by the many TCP flows
passing through a core link? I.e. What percentage of the packets will
be performing PMTUD and have the DF bit set, requiring the generation
of an ICMP message?


Keith Schuettpelz