[ClusterLabs] Corosync Transport- Knet Vs UDPU

[Strahil Nikolov]

One huge benefit of the new stack is that you can have 8 corosync rings, which is really powerful.
Best Regards,Strahil Nikolov
 
 
  On Mon, Mar 28, 2022 at 9:27, Christine caulfield<ccaulfie at redhat.com> wrote:   On 28/03/2022 03:30, Somanath Jeeva via Users wrote:
> Hi ,
> 
> I am upgrading from corosync 2.x/pacemaker 1.x to corosync 3.x/pacemaker 
> 2.1.x
> 
> In our use case we are using a 2 node corosync/pacemaker cluster.
> 
> In corosync 2.x version I was using udpu as transport method. In the 
> corosync 3.x , as per man pages, the default transport mode is knet . 
> And in knet it uses udp as knet method.
> 
> I have the below doubts on the transport method.
> 
>  1. Does knet require any special configuration on network level(like
>    multicast enabling).


No. What knet calls UDP is similar (from the user POV) to corosync's 
UDPU, it's a unicast transport and doesn't need any multicast 
configuration.

Sorry that's confusing, but it's more technically 'correct'. The main 
reason UDPU was called that was because it was new to corosync when the 
old (multicast) UDP protocol caused trouble for some people without good 
multicast networks.


>  2. In corosync 2.x udp was used for multicast, in knet transport does
>    udp mean multicast.

No, see above. There is no multicast transport in knet.

>  3. Will udpu be deprecated in future.
> 

Yes. We strongly recommend people use knet as the corosync transport as 
that is the one getting most development. The old UDP/UDPU protocols 
will only get bugfixes. Knet provides muti-homing up to 8 links, and 
link priorities and much more.

I wrote a paper on this when we first introduced knet into corosync 
which might help:

https://people.redhat.com/ccaulfie/docs/KnetCorosync.pdf


Chrissie


> Kindly help me with these doubts.
> 
> With Regards
> 
> Somanath Thilak J
> 
> 
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