Re: [Xen-users] bonding + VLANs -> Oops/panic, no VLAN on 100 Mbit cards [SOLVED]

["Fajar A. Nugraha" <fajar@xxxxxxxxxxxxx>]

Tomasz Chmielewski wrote:
> Fajar A. Nugraha schrieb:
>> - Create vlans and bridges in dom0 using your distro's network config.
>> - If you need bonding and have more than two dom0 interface handling
>> domU's traffic, do the bonding in domU.
>
> Doesn't make much sense to me to do bonding in domU.
> What if you want to live migrate the guest to a host which doesn't
> have two cards?
>
> Also you wrote it earlier ("I doubt it would work as expected anyway,
> since the only way to get bonding and vlan in domU is to detect line
> status (which would be rather useless if the network problem happens
> anywhere other than the switch)") - so I'm not sure what you mean.
>
>

I believe it all comes down to your this line :
I doubt it would work as expected anyway, since the only way to get
bonding and vlan in *dom0* is to detect line status (which would be rather
useless if the network problem happens anywhere other than the switch)

I made a typo earlier, it should be dom0, not domU. The reasoning behind
that statement is :
1. there are several method that linux ethernet bonding use for link
monitoring, ARP monitor and the MII monitor
2. The best HA setup (IMHO) would be to use ARP monitor, and use router
IP as arp target.
3. Using vlans means multiple networks and multiple routers are involved.
4. Checking only one router ARP (the router on native-vlan) isn't really
good enough (for me anyway) since it doesn't check the conditions of
routers on other VLANs
5. MII monitor only check whether the link (the switch or hub that your
eth is connected to) is up. It doesn't really check whether the switch
connection to the router is working properly or not.

Which is why, IMHO, the best way to do bonding is in domU, and use dom0
for VLAN and bridge.
If you ever get a solution that would RELIABLY do bonding (as in capable
of checking each VLAN's router ARP) in dom0, I'd love to hear about it :)

Regards,

Fajar

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