Re: ICMP responses to broadcasts

Mike Brescia (brescia@BBNCCV.ARPA)
15 Apr 86 10:32:51 EST (Tue)

     Let me second John Romkey's assertion that no good ICMP implementation
     should send redirects in response to a broadcast packet. Might I also
     ask at this time why our core gateway does just that?

Chris, your gateway is on a ring. Its driver does not recognize broadcasts as
such, and will rebroadcast them as well as send a redirect each time it comes
around until the TTL disappears. This means that if the TTL is 10, you get 10
copies of the 'rwho' packet and 10 redirects. This has been the case since
day one on the ring. (It had been fixed in fibernet and ethernet drivers long

The fix in the gateway is to drop all IP-type packets addressed to
'hardware-broadcast' before they leave the local net layer.

This is the first report of this being some kind of problem. We'll put it on
the queue of things to fix before the latest release is completely frozen.


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