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Originally Posted by vinguy51 what is load balancing.... |
Load balancing is a very generic term for any system where two or more devices share the burden of some task.
Load balancing is used in computers to have multiple servers process requests concurrently.
Load balancing is used in networking to have multiple network devices and multiple network links work together to provide greater total bandwidth.
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Originally Posted by vinguy51 i want to know about loadbalancing of ospf. |
Ahhh... now we're getting somewhere.
OSPF (Open Shortest Path First) is a
routing protocol. In fact, OSPF is the preeminient IGP (Interior Gateway Protocol) in use today.
The task of a routing protocol is to decide where to send (route) packets to get them to their final destination in the best way possible.
Load balancing is one of the tools OSPF uses to do this. If an OSPF
router has multiple links which all leads to the destination, it can decide to send packets out on one, some, or all of the links. The end result can be that the data will arrive at the destination more quickly.
OSPF load balancing decisions are based on a factor called "Cost." Cost is a bit of a confusing term, because it does not mean "cost" in the familiar context of dollars and sense. By default, the "cost" of a link is based upon the bandwidth of that link -- but you can manually set the "cost" of a link based upon any criteria you choose.
Let's say that you have a T-1 line and a 10Mb fiber circuit. The T-1 line would have a default cost of 64 and the fiber circuit would have a default cost of 10. OSPF would route a lot of packets over the "cheaper" fiber circuit.
Let's say that you then notice some unexpected latency on the T-1 line. You could raise the cost of the T-1 line in your OSPF configuration and OSPF would route even more packets over the fiber circuit.
Make sense?
ospf 
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