Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

OSPF dead interval

If an OSPF router receives from its OSPF neighbor an OSPF packet other than Hello packet (i.e. LSA, LSAck), is dead interval reset anyway?

Regards

Stefano

7 REPLIES
Hall of Fame Super Bronze

Re: OSPF dead interval

What "other" OSPF packet can it be ?

New Member

Re: OSPF dead interval

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

Stefano

Hall of Fame Super Bronze

Re: OSPF dead interval

AFAIK, there isn't any other packet.

Re: OSPF dead interval

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.

New Member

Re: OSPF dead interval

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.

Gold

Re: OSPF dead interval

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....

HTH.

:-)

Russ

Re: OSPF dead interval

Yes it does..I even simulated it to confirm

Narayan

396
Views
10
Helpful
7
Replies