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Re: [Xen-users] network setup with one bonded interface and one virtual interface

  • To: XenUsers <xen-users@xxxxxxxxxxxxx>
  • From: Alexandre Kouznetsov <alk@xxxxxxxxxx>
  • Date: Thu, 11 Oct 2012 13:39:48 -0500
  • Delivery-date: Thu, 11 Oct 2012 18:41:33 +0000
  • List-id: Xen user discussion <xen-users.lists.xen.org>


El 11/10/12 12:48, Adam Gold escribió:
I wanted to thank you for an extremely clear and helpful response.
Great it was useful!
It happened that I just have delivered a similar setup, so I had the examples at hand.

going to work through trying out your suggestions and I may – if you
don't mind – revert with some additional questions if I have any.
Sure thing. Why don't you post them to the list?
You could get more feedback, and any answer will be indexed by search engines for future reference. In any case, I'll watch for it.

of interest, if redundancy is the priority, which bond mode would you
recommend?  From what I read here it seems active-backup is the
way to go:

Can't tell for sure. I work with few bonded interfaces, so my knowledge is too theoretical. I picked up configurations based on than, made tests, they gave expected results, so I stayed there.
Check http://www.linuxhorizon.ro/bonding.html fro resumed reference.

My favorite is 802.3ad aka mode=4. It seems to be smart enough to balance the traffic and provides failover. If I unplug one cable, in the worst case I'll loose a few packets (TCP will easily correct that).

There are switches that clam they support 802.3ad, but in practice it turns they have a nonsense called "static LACP" (the standard implies that there is no 802.3ad without LACP). In that case I have successfully used balance-xor aka mode=2.

Never needed a pure failover without traffic balance. In case I needed that, I would choose between active-backup aka mode=1 and broadcast aka mode=3. The second one is more stupid, in the best sense of the word, so I can think of cases when it's preferable.

If you think of fault tolerance, consider that the bonding is frequently done with ports on the same switch. Unless you have a fine piece of equipment that supports fancy stacking, which could have different ports of the same bond on different switches. It your bond is on the same switch and the switch dies, so does the bond, forget your fault tolerance. So, you better imagine your scenarios (intentional unplug of cable while making movements, broken cable, dead Ethernet port, etc), test (simulate) them and decide if the behavior of your setup is acceptable or not.


Alexandre Kouznetsov

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