> Dont post networking related patches on other lists. I havent seen said
> patch, but it seems someone is complaining about some behavior changing?
For some strange reason I didn't find the beginning of thread either from
archive, the first post seems to be
I'm trying to summarize. The approach - one raw socket to send/receive
messages no matter how many interfaces are used - worked for Quagga/Zebra
routing software daemons till now. If some of these interfaces was
operationally down, socket wasn't blocked even if the queue was full. In
fact "man sendmsg" has still text:
The output queue for a network interface was full. This gener-
ally indicates that the interface has stopped sending, but may
be caused by transient congestion. (Normally, this does not
occur in Linux. Packets are just silently dropped when a device
Seems that it's no longer true. Seems that kernel is now trying as hard as
possible not to loose any data - data is queued and if the queue will be
full, all related sockets will be blocked to notify application. So, one
socket approach don't work any more for Quagga/Zebra. No problem, we can
take the "one socket per interface" approach. And we already have link
detection implemented to notify daemons.
But there will be still potential problem - sending the "interface down"
message from kernel to the zebra daemon and then to the routing protocol
daemon takes time. And during this time daemon can send packets which will
sit in queue and may cause many problems if sent to the network later (if
link comes up again). Think about statelss routing protocols like rip(ng),
ipv6 router advertisements etc. They may carry the info that's no longer
true causing routing loops etc.
And to clarify a little bit: no - the Quagga/Zebra didn't work with previous
approach perfectly. I fact with link detection and socket per interface it
will be better than ever no matter what's the kernel behaviour. We just
want to make sure that solution will be bulletproof.
So, problem - how can we make sure that no potentially dangerous aged
(routing) info will be in the network?
Elion Enterprises Ltd.