Answer to PurnaChand's question: Hello packets are for neighbor discovery/recovery. Hello packets are not counted for DUAL FSM while calculating loop free routes. DUAL operates with three basic message types: QUERY, UPDATE, and REPLY. This is the reason even though routers are sending/receiving hellos but still reset the neighbourship after 3 min in Active state. There were few enhancements made with SIA query/reply in later codes (12.1 and above). Refer the RFC 7686 for more details.
"EIGRP sends hello packets every 5 seconds on high bandwidth links and every 60 seconds on low bandwidth multipoint links." If R1 and R2 doing their regular hello thingy for every 5 seconds, how could anything possibly go wrong to extent that R1 thinks R2 is dead and break the neighbourship?
PurnaChand Medisetty Stuck in active is feature that is not related to timers. When router is looking for specific route and neighbor router doesn't respond within SIA time. Router will automatic declare neighbor is down with termination message.
PurnaChand Medisetty No Purna. They send hello but hold down timer must be less then stuck in timer configured. this post may help you www.networkers-online.com/blog/2008/08/eigrp-timers-hello-hold-down-and-active/
It's been a year; I still don't get it. Let us presume a hello came in from R4 to R2 with a hold-timer of 3 minutes and just about the same time R2 went active sending query to R4 (with stuck-in timer of 3 minutes) but after a minute another hello is expected from R4 resetting R2's hold timer back 3 minutes. 3 minutes from the beginning of presumption, R2 has received 3 times hello from R4 but no query-reply yet about that active route. so what is going to happen now? is it going to keep the neighbourship that it just received a hello from R4 or is it going to tear down the neighbor as it's been 3 minutes since query was sent? the link between R1 and R2 with hellos of 5secs. :s
loved that fire sound.. when link goes down :D
Thankyou Kevin Wallace
Answer to PurnaChand's question:
Hello packets are for neighbor discovery/recovery. Hello packets are not counted for DUAL FSM while calculating loop free routes.
DUAL operates with three basic message types: QUERY, UPDATE, and REPLY. This is the reason even though routers are sending/receiving hellos but still reset the neighbourship after 3 min in Active state. There were few enhancements made with SIA query/reply in later codes (12.1 and above). Refer the RFC 7686 for more details.
Go to 7:38 if you want a real quick explanation lol
thanks bruh
hello packets donot help to prevent breaking?
Love your explanation
Perfect explanation!
Really super explanation excellent
Super
"EIGRP sends hello packets every 5 seconds on high bandwidth links and every 60 seconds on low bandwidth multipoint links." If R1 and R2 doing their regular hello thingy for every 5 seconds, how could anything possibly go wrong to extent that R1 thinks R2 is dead and break the neighbourship?
PurnaChand Medisetty Stuck in active is feature that is not related to timers. When router is looking for specific route and neighbor router doesn't respond within SIA time. Router will automatic declare neighbor is down with termination message.
Okay..... so is it like they stop exchanging hellos with every neighbor when one router goes active for a route?
PurnaChand Medisetty No Purna. They send hello but hold down timer must be less then stuck in timer configured. this post may help you www.networkers-online.com/blog/2008/08/eigrp-timers-hello-hold-down-and-active/
Thanks Dinesh .... you addressed my doubt !!
It's been a year; I still don't get it. Let us presume a hello came in from R4 to R2 with a hold-timer of 3 minutes and just about the same time R2 went active sending query to R4 (with stuck-in timer of 3 minutes) but after a minute another hello is expected from R4 resetting R2's hold timer back 3 minutes. 3 minutes from the beginning of presumption, R2 has received 3 times hello from R4 but no query-reply yet about that active route. so what is going to happen now? is it going to keep the neighbourship that it just received a hello from R4 or is it going to tear down the neighbor as it's been 3 minutes since query was sent? the link between R1 and R2 with hellos of 5secs. :s
It's "actively" screwed