[ClusterLabs] Antw: [EXT] Re: Corosync Transport‑ Knet Vs UDPU

[Ulrich Windl]

>>> Strahil Nikolov via Users <users at clusterlabs.org> schrieb am 28.03.2022 um
15:49 in Nachricht <1758982440.559085.1648475365443 at mail.yahoo.com>:
> One huge benefit of the new stack is that you can have 8 corosync rings, 
> which is really powerful.

Hm I wonder:
If one ring is not good enough and two rings are not good enough, then per induction n+1 rings aren't good enough also, so 8 rings don't really help ;-)

Sorry for the joke!

Ulrich

> 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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