From: Brian W. <br...@te...> - 2004-10-14 15:50:49
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On Thu, 2004-10-14 at 10:29, Keir Fraser wrote: > > So the xen side of the vif isn't see on the wire except for a: the > > backend driver domain( usually domain-0) and that vif's front and driver > > domain eh? (I got the front and back end locations right yes?) > > Noone ever sees the backend MAC address -- it is never written into > any packet. We only need to give the backend a MAC address because we > hook into the Linux networking code as a normal Ethernet interface, > and normal Ethernet interfaces need a normal MAC address. :-) > It needs to be unique because of sanity checks in the bridge that fail > if it sees a remote address == a local address that it knows about. > > > Either way it goes, how would one go about verifying that the MAC is > > truly unique on it's visible lan? I'd be i very interested in this as a > > safety precaution. Right now I can't think of how to do the uniqueness > > test... 8-P if someone can give me an idea or two I could try to code it > > since it's something that I want.(brain fried this morning) > > I'm pretty sure there's no way of soliciting a response from an > Ethernet host without using some higher-level protocol; probably IP or > RARP. RARP is hardly ever used, but maybe if you know the IP subnet > you could do a broadcast ping and collect the responses and look at > their source MAC addresses? > Hmm, not a bad idea.... :) I know brctl can be used to query for a list of MACs on it's physical lan that it has cached. Maybe if xend on domain-0 did something similar using ARP and arp-reply packets that it sees on the bridges to vet it's mac choices against, and issue a warning if it sees a dupe? > -- Keir <snip - backlog shortened > |