Which converges faster eigrp or ospf

It effectively calculates the shortest path with minimum network traffic when the change occurs. OSPF protocol is used for passing the information from one adjacent area to another one.

Shortest Path only depends on bandwidth for metric calculation of the cost of a particular link, while DUAL uses bandwidth and delay to calculate the composite metric with a complex formula.

OSPF maintains the complete information about the routers in its area. Each time there is a change within the area, all routers need to re-sync their database, which makes it more CPU intensive.

EIGRP, on the other hand, has triggered and incremental updates and will not send all the information about the network rather just the information that has changed will be shared. When a network becomes unreachable from the best path, EIGRP can fall directly to the alternate best path. OSPF, however, involves a small time to install a new route and re-route traffic once a failure occurs.

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Login details for this Free course will be emailed to you. Email ID. Contact No. AD just decides who gets to install routes in the routing table, thats a different thing. Also if you leave the timers to their default values in both the protocols, EIGRP has a faster convergence because of 5 second hellos and 15 seconds hold time, and yes obviously this is changable in both EIGRP and OSPF giving power to the network administrator about what time it should take for the neighbor to be declared dead, in both the protocols.

But ospf also supports subsecond hellos, so it wins ultimately in this case! Is Perfect example and very intersting vision of how can influenced the convergance of routing protocol. And can show for understanding how of certain case and depend of configuration some routing protocol can be fatser than another. The Reflection of Pritish he highlights and focus on algorithm and timer for me is very helpful and good vision. A lot of good stuff. Thanks everyone who shared their ideas here.

One more question:. What are sub-second hellos for ospf? Is that simply a manipulated hello interval? OSPF fast hello packets refer to hello packets being sent at intervals of less than 1 second. OSPF fast hellos are configured using the ip ospf dead-interval minimal hello-multiplier interface command.

The dead interval is set to 1 second, and the hello-multiplier value is set to the number of hello packets you want sent during that 1 second. You can send between 3 every milliseconds and 20 every 50 milliseconds. Internet Address Timer intervals configured, Hello msec, Dead 1, Wait 1, Retransmit 5. Changing hello intervals to 5 times in a second!! Sounds like high router cpu utilization. Just curious to know, is that practically applicable.?

I guess, high cpu utilization is a drawback to ospf when fast hello's are used direct me if I am wrong. The some ones that apply to all super low Hello timer settings. Link flaps of some kind. The interface bounces down the OSPF adjacencies fall and then it comes right back up.

Or momentary congestion on the interface that prevents Hello packets from being sent or received due to bad QoS-ing. I'd be glad to see responses from experienced members too. Of course, cpu is utilized every time when it sends or receives these hellos. And it's not as lightweight as BFD. But If you neighbor doesnt support BFD you cannot implement it, as its a keepalive mechanism and has to be 2 way.

Here I found an interesting documentation which says:. I'm wondering where neighbor loss cannot be detected by L1 and L2 failure?! In NBMA networks?? First thing that comes to mind is Unidirectional Links. If the interface can send and not receive then the line protocol of the interface may not go down think fiber connections.

In this instance, the interface will stay up but Hellos will not be sent and OSPF will know something is wrong even though physically the router believes everything is okay enough. I guess I'm not familiar with it at all. What is it? And how is it possible?

Could you tell me about it in brief, if possible? Fiber connections use two strands of fiber each. One to Transmit and one to Receive. Typically if one fails then the link will go down. But if there are external circumstances of some kind, one of those strands may only have enough connectivity to create a link up status but not transmit actual data.

Jokes aside, you seem to be familiar with many IT technologies. It's cool. Judging by your previous posts you're also good at radionics. Thanks to Cisco. It introduced many networking concepts to me at a technical level. I try to read from many sources to seize an overall picture. Far from it. I just have the advantage or disadvantage of being in an environment that exposes me to a lot of technology.

So I know a little bit about a few things. The key is I only respond to things I know a little bit about lol. The key in this field is experience and how much you are willing to read on your own.

I only have 3 years in a small environment but I read almost everyday. There are people here who have decades of experience and can talk technical circles around me easily.

EDIT: Not sure about the radionics part either I just know that signal strength is measured in decibels and that you want to lose as little as possible when terminating fiber optic cables. I found a job at ISP.