s-durando Fri, 11/09/2007 - 06:56

Any OSPF packet other than Hello: LSA, LSU, LSR, LSAck


bvsnarayana03 Fri, 11/09/2007 - 07:08

All OSPF packets like LS Request, Update, & Acknowledgement are a part of Hello packet only. They are not exchanged as separate packets. However for identification, each packet type contains its own header format within a HELLO. And ofcourse everytime a HELLO is received, the timer gets reset.

Happy Diwali.

michael.laplante Fri, 11/09/2007 - 10:12

That's not what I'm inferring from my book, Routing TCP/IP Vol I. There are separate and distinct packets for each type. Only the HELLO has what is needed to keep the neigborship up. (the hello and dead intervals, options, network mask)

All packets have the same header and in the header there is a field for a type code (1 - 5) to distinguish what type of packet it is.

So I would answer the original question as no, the dead interval would not get reset each time any packet is received, only when it receives a HELLO.

It wouldn't be to hard to lab this up. set the hello and dead intervals to something high, then create a loopback and advertise it into OSPF and sh ip ospf ne to see when the dead timer is to expire and if it got reset after the new LSAs advertising the new loopback network.

ruwhite Fri, 11/09/2007 - 11:12

Yes... IOS resets the dead interval for all OSPF packets received. I seem to remember a time when this wasn't so, and a discussion about changing it, but the current code always resets the dead timer, and I can't track down anything about it ever being different, so....





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