On 19/05/2011 12:32 PM, Ben Greear wrote: > On 05/19/2011 08:24 AM, Philip Hugg wrote: >> Hello everyone, >> >> I'm currently working on Xorp-OLSR. >> >> The problem with OLSR is the route flapping. >> I've managed to find a few obvious bugs up to now however this one >> involves the interface to the XRL. I'm not sure how to fix. >> >> The problem I found is in file 'xrl_port.cc' where OLSR is sending the >> packets > >> >> Now what I'm seeing is the debug message "PortOutput ...: send skipped >> (pending XRL)". >> It doesn't happen all the time but it's just enough to cause route >> flapping. >> >> My question is how could I fix the pending issue without causing a race >> condition in the code? > > I took a look at that code, and it looks quite fragile. > As the code exists currently, I suppose you'd > need to check the results of send_to and queue up pkts for retransmit > if sending failed. > > Maybe it was to make sure some initial config logic completed before > send_to started functioning? > > Maybe use a different flag like _setup_complete that is set in > socket_setup_complete() and have send_to fail to send until > setup is complete? > > It doesn't look like an general XRL problem to me, by the way. > > Thanks, > Ben > Hi Ben,
Thank you for answering so quickly. I presume the socket setup is done when xorp is started and is done only once. In my case, the socket has been setup and is currently sending and receiving packets. The problem I'm seeing is that when a send-to call is made it becomes busy (pending=true) for a short while. It is freed (pending=false) when the callback 'send_cb' is returned from cl.send_send_to(...). It just sometimes happens that OLSR is sending packets in that short busy state. To me, this is a problem! A queuing mechanism on the OLSR side would probably mean implementing a new thread of code just spinning and waiting for the XRL to become free. This will take a while but I'll take a look at the other protocols (BGP, OSPF) to see how they are handling the XRL pending. again thanks, Phil. _______________________________________________ Xorp-hackers mailing list [email protected] http://mailman.ICSI.Berkeley.EDU/mailman/listinfo/xorp-hackers
