Disadvantasges from OSPF?

Is OSPF very hard to configure?. What are the main disadvantages of using OSPF. I just want to make sure before I get it into it.

Thank You
Greg

[Slaine]

The cons are - you need good spec routers and the concept of having seperate areas, but it isnt that hard to configre.

[whcdavid]

Also, memory and CPU requirements that can affect even high-end router performance. You can configure more than one OSPF process, but you must know that the shotest path first calculations associated with multiple OSPF processes can consume a considerable amount of CPU and memory.

Just my 2 cents.


Thank You
David.K

[Slaine]

And if you are using the area concept, if say area0 which is your main router goes down then the other area routers will not be able to communicate with each other.

This is because they only know what is in there area, if they dont then they forward the packet to the main router which forwards it again to the correct area.

It's a little bit like dns.

Ta

George

[Slaine]

Plenty of flash and dram memory in your routers are needed for this one.

hi guys

Tell me how good is it to go for OSPF implementation, as my organistaion is about to put that in place. Can any one there send me some advantages & disadvantages of OSPF

Well lets see..
OSPF:
Keeps a link state database of all known routes (fast convergence)

Stub Areas (Keep cpu load off of less capable routers, while larger routers handle the backbone)
With stub areas you have highly summarized routes, or just simply a static route out of the network.
This keeps slower routers from having to use memory and cpu, also keeps them from having to converge when their is a link down or flapping.

Each OSPF router has its own link state database, not learning of what routes to use from some random other router.
Having its own map it can inject loop free routes into the routing table.

Highly configurable over mutiple network types

As for Slaine's responce..
This is true but OSPF is made for redundancy and fast convergence..
Building a proper network whould include at minimum three routers in the ospf core.
All of them linked back to back for full redundancy.

One other disadvantage is that all areas must be directly linked to the backbone/core area 0.
You can use a virtual link between one area to get it to the core but for a couple of reasons this is not recommended..

Area 5 -------- Area 2 -------- Area 0 'Backbone'
|-----------VirtualLink--------------|

my teacher once said that all areas need to be around area 0 - the backbone
so..you need design your network around this area, a constraint other routing protocols don't have
also ospf stores info about the whole area and needs to reprocess the routing table whenever there are changes, which will consume large amounts of resources, thus requiring high end routers

[sanjay]

hi there
i have heard a lot about these routers but i did not know the cons of these routers.so, the info you provided is quite valuable to me. so,thanks alot for the same.

[princee18]

there are some pros of ospf but the cons are also many like:
1. very intensive processor
2. maintaining multiple copies of routing information, increasing the amount of memory needed
3. OSPF can be logically segmented by using areas
4. not as easy to learn as some other protocols
5. if an entire network is running OSPF, and one link within it is "bouncing" every few seconds, then OSPF updates would dominate the network by informing every other router every time the link changed state.