Subject: Re: Path MTU discovery
To: None <tech-net@NetBSD.ORG>
From: Michael Richardson <firstname.lastname@example.org>
Date: 07/16/1997 02:56:32
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>>>>> "Jonathan" == Jonathan Stone <jonathan@DSG.Stanford.EDU> writes:
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.
Jonathan> PMTU is also useful if you have an Ethernet subnet at
Jonathan> home, with a SLIP or PPP connection configured to a low
Jonathan> MTU (256 bytes) for latency reasons.
I, for one do. However, since prior to PMTU, you were supposed to
assume an MTU of 576 for non-local TCP connections, it doesn't affect
me. It affects people that have their PPP MTU set to a higher value.
And, so, if *YOU* access my machine, across my rather loss link, (my
fault, not my ISP's) then doing too much fragmentation affects your
speed. Believe me: I'm across the world, and I know how bad my link
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