[PVE-User] Cluster network via directly connected interfaces?

[Ronny Aasen]

Personally if i was to try and experiment with something non-default I 
would try to use ospf+bfd either with bird or quagga.

-you get quick failovers due to bfd.
-you can equal cost multipath links to utillize multiple ports between 
servers.
-All links are active, so you do not have a "passive" link, as you have 
with STP
-and there is no needless duplication of data, so you do not get the 50% 
bandwith loss of a broadcast bond.
-you need to use corosync with targeted udp towards spesific loopback 
addresses.
-traffic goes shortest path. so allways towards the correct server.
- you can very easily expand beyond 3 nodes if you have enough ports. Or 
move the ospf domain onto a switch if needed. this also easily converts 
to a multiple switch config to maintain HA and no SPOF

Happy experimentation!

mvh
Ronny Aasen





On 11/22/18 7:29 PM, Frank Thommen wrote:
> Please excuse, if this is too basic, but after reading 
> https://pve.proxmox.com/wiki/Cluster_Manager I wondered, if the 
> cluster/corosync network could be built by directly connected network 
> interfaces.  I.e not like this:
> 
>   +-------+
>   | pve01 |----------+
>   +-------+          |
>                      |
>   +-------+     +----------------+
>   | pve02 |-----| network switch |
>   +-------+     +----------------+
>                      |
>   +-------+          |
>   | pve03 |----------+
>   +-------+
> 
> 
> but like this:
> 
>   +-------+
>   | pve01 |---+
>   +-------+   |
>       |       |
>   +-------+   |
>   | pve02 |   |
>   +-------+   |
>       |       |
>   +-------+   |
>   | pve03 |---+
>   +-------+
> 
> (all connections 1Gbit, there are currently not plans to extend over 
> three nodes)
> 
> I can't see any drawback in that solution.  It would remove one layer of 
> hardware dependency and potential spof (the switch).  If we don't trust 
> the interfaces, we might be able to configure a second network with the 
> three remaining interfaces.
> 
> Is such a "direct-connection" topology feasible?  Recommended? Strictly 
> not recommended?
> 
> I am currently just planning and thinking and there is no cluster (or 
> even a PROXMOX server) in place.
> 
> Cheers
> frank
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