[ClusterLabs] Antw: Re: EL6, cman, rrp, unicast and iptables

[Noel Kuntze]

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Hello Ullrich,

> Actually I don't understand that claim: If packets are delivered in order
>(mostly), any TOTEM packet has the same change to arrive than any other packet.
> While all other communication protocols can actually deal with Ethernet and the
> Internet, TOTEM is the only protocol that can fail even in a switched LAN. I
> haven't benn convinced yet that it's not an implementation issue of TOTEM.
> Instead of telling people to fiddle with their network configuration, I'd
> prefer putting more efforts into fixing TOTEM.

I assume with "change to arrive", you mean delay? Or do you mean the ordering of
the packets?
Totem behaves like it does because it needs to detect a failed node, afaik.
This is something that no other protocol you encounter on the internet/LAN is supposed to do.
All of those protocols are either for error reporting (ICMP) or for transceiving of
data (udp/tcp). UDP obviously has no congestion algorithm, but TCP does.

> The main problem with priorities is who decides what is most important,
> especially if a medium is shered by many different software stacks and
> applications.

Obviously some type of prioritzation has to be done, or at least should be done,
because some things *are* more important than others. The only thing that can
control congestion centrally in a computer system is the interface that controls
access to it, so it's either the NIC or the software that controls access to it, so the network stack
of the operating system. The problem is a different one when the LAN is bridged, rather then switched, because then
the transmission of other hosts affects the transmission of one host.
- -- 

Mit freundlichen Grüßen/Kind Regards,
Noel Kuntze

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