Gratituous ARP and the em driver

[Nielsen]

Yes, this is the case. I tested it again, and the arp packet in question 
doesn't get to the other machines. The sending machine does send 
gratituous arp, however the em NIC is down for 3 or 4 seconds, and the 
packet isn't sent on the wire.

I find it odd that the em driver would need to reinitialize the NIC each 
time an alias is added. I haven't seen any other network drivers do this.

And, yes, it occurs every time an alias is added or removed from the 
NIC. Not just the first time.

Cheers,

Nate

Robert Watson wrote:

>On -1 xxx -1, Nielsen wrote:
>If you run tcpdump on the machine to sniff the interface in question
>looking for arp packets, does tcpdump see the gratuitous arp?  I'm
>guessing that it does, and the lack of sending the arp is a result of
>delays in negotiating on the wire.  Does this problem turn up only the
>first time you raise the interface, or every time you change the IP
>address on the interface? 
>
>Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
>robert at fledge.watson.org      Senior Research Scientist, McAfee Research
>  
>