In what basis routing protocol is choosed in a network

[bagvanliju]

Hai ,

In one interview this qstion was asked ..how do we choose a appropriate routing protocol for a network ....y ospf y bgp etc ..can some one help me in clearing this

thank in advance

ujil

[Edison Ortiz]

The selection of one routing protocol tends to be a religious discussion.

If you are going to run a network with the same routing policies, I recommend selecting an IGP. The most common IGPs are EIGRP and OSPF. Many networks select EIGRP for its simple configuration but it has some drawbacks such as: proprietary protocol and not as scalable as OSPF.

OSPF, in the other hand, is the number 1 choice of IGP in large networks. With that said, you need to be very careful with its design and it can become quite messy very fast.

If you want to have a network with different routing policies, then the ideal protocol is BGP.

For instance, you have a segment of your network in Tokyo and another segment in New York, it's often recommended to run IGP within Tokyo (OSPF) and BGP between Tokyo and NY.

HTH,

__

Edison.

[bagvanliju]

hai Edi,

thanks a lot that was very infomative ....now its clear ...one more thing is there any role of interface (Type) in selecting the protocol ..for eg:if i am running ospf in serial interface and ethernet interface will there be any diffrence .....pls forgive if this is a rubbish qstn ...

ujil

[Edison Ortiz · Accepted solution]

Each routing protocol has its own idiosyncrasies, for instance when running EIGRP on a multipoint serial interface (hub and spoke), you have to be aware of the split horizon rule.

When it comes to OSPF, the type of network OSPF defaults to, relies on the interface type. Ethernet defaults to broadcast while point-to-point serial interfaces defaults to point-to-point. As you know with OSPF, the network type must match in order to form adjacency so that's something to be aware of.

With that said, selecting one routing protocol over the other is never due to the type of interface running in the router but the selection is done based on the customer's requirement with their hardware, topology and expertise.

HTH,

__

Edison.

[bagvanliju]

hai Edi,

i am tru now .....thanks a lot once again

ujil