Eli Dart wrote:

The networks that are apparently working fine are most likely misconfigured, IMHO.

Others have made a case for permitting an interface to accept as large a packet as it can, regardless of configured MTU. That's fine for theory.

My operational experience leads me to a different place. If an interface receives a packet that is larger than its configured MTU, I would prefer that the packet be dropped as a giant and a giants counter incremented, regardless of whether the hardware can theoretically receive the packet. In modern networks, an MTU mismatch within a broadcast domain indicates a broken network, IMHO. If the devices in the network are configured to enforce MTU for both tx and rx, more problems get spotted during turnup, rather than surfacing later on as difficult-to-diagnose problems that users only call about after they are truly frustrated. And, if you have a giants counter (or input error counter) you can look at, it makes it straightforward to spot the problem.

(one could also stretch a bit and say that enforcing MTU on rx might provide less surprise to code that consumes packets and has knowledge of the MTU setting of an interface.....unfortunately I don't know enough about the details of the network stack to know if this is a real concern)

100% agree! :)

--
           Sincerely yours,
                            Artyom Viklenko.
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[EMAIL PROTECTED] | http://www.aws-net.org.ua/~artem
FreeBSD: The Power to Serve   -  http://www.freebsd.org
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