[Fedora-xen] Xen network bridge questions (using network configuration tools provided by distribution)

[Bertho Stultiens]

Pasi Kärkkäinen wrote:
[snip]
> 1. Changes the MAC-address of peth0 to FE:FF:FF:FF:FF:FF. If I have another
> physical interface, peth1, can it have the same MAC address, or does it have 
> to be different? 

In principle, all unicast MACs in a broadcast domain have to be unique.
Each vlan is a broadcast domain, so that is fine. However, the kernel
has a slightly different view of the interfaces and I an not sure that
it can keep everything properly isolated. The FE:FF..FF addresses are
fake anyway and should be local only. There is then the STP problems you
can run into depending on whether you have all isolated STP instances
for each vlan/interface.

To make a long story short :), use unique MACs to avoid problems. You
can use them f.ex. from the 00:01:01, 10:00:00, ac:de:48... (and there
are more private MAC pools defined; see
http://standards.ieee.org/regauth/oui/oui.txt and look for PRIVATE).

[do not use MAC addresses with an odd numbered high octet; these are
reserved for multicast/broadcast]


> 2. Sets peth0 to NOARP (disables ARP). Why is this? Is it a requirement? 
> 3. Sets xenbr0 to NOARP. Same question goes for this.

The NOARP is because you do not want the interfaces to answer to arp
requests. Neither interface has an IP address assigned, so they are to
be local only and their MAC should not propagate. It is a requirement so
far as to have them shut up...


> I have working setup with FC6 network scripts/tools, but I'd like to make
> sure I do the correct things.

If you also could post your resulting scripts or make a micro-howto,
that would be great too. Polishing can be done on the list I guess.


-- 
Greetings Bertho


Bertho Stultiens
Senior Systems Manager
Mobilethink A/S