Subject: Re: Path MTU discovery
To: None <tech-net@NetBSD.ORG>
From: Michael Richardson <email@example.com>
Date: 07/16/1997 02:38:19
>>>>> "Wolfgang" == Wolfgang Rupprecht <firstname.lastname@example.org> writes:
Wolfgang> mo@UU.NET (Mike O'Dell) writes:
>> but if you put an FDDI interface into your box and have it talk
>> to another server, how will your hard-wired MTU of 1460 take
>> advantage of half as many packets per NFS transfer??
Wolfgang> Under NetBSD the MTU is specifiable on a per-routing
Wolfgang> table entry basis. If I had an FDDI I'd simply allocate
Wolfgang> a network for the FDDI and set that MTU to 4k (or
Wolfgang> whatever the exact number is). Adding the following to
Wolfgang> the rc file, sure is faster than adding the
Wolfgang> MTU-discovery code to the kernel.
Wolfgang> route add -mtu 4096 -net x.x.x.0 myinterface
Yes, but that isn't the point of PMTU discovery.
The point is to figure out that there are FDDI networks from A<->B
and so that *NON-LOCAL* packets can be bigger.
In any case, the reason I wanted PMTU code (which I understand now
that FreeBSD has) is because I want to determine if my implementation
of PMTU ICMP's in an IPsec security gateway works correctly.
] It isn't that sun never sets; rather dawn and dusk are united | one quark [
] Michael Richardson, Sandelman Software Works, Ottawa, ON | two quark [
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