Umesh,

Umesh_MS wrote:

> Hi..
> Can anybody say,what are the steps needed to calculate the nexthop?
> i am not clear about the RFC 2328.
>
> 1.what are the things needed to calculate the nexthop?

section 16.1.1 explain in detail this so I propose you to read this section

>
> 2.Need the neighbor router in every nexthop?

No, a given node will inherit the outgoing interface and next hop ( if
needed ) from its parents.
note that the root is the parent of its neighbor ( not always see below )

>

>
> 3.what is mean by inherite the nexthop if the destination is not
> directly connected?

ok let's put it in a simple way, imagine 3 routers A--------B--------C
A is the root ( calculating router) , B is directly connected to A so in
order to find the next hop and outgoing Interface A will look at it's own
router LSA to see what is the outgoing Interface to reach B and next hop if
needed ( p2p doesn't need ) you look at B's Router LSA and the link data
field will give you the next hop
now B is the parent of C so C will just inherit the next hop and outgoing
interface of B in other words
" I don't have a direct connection to C and I go through B to reach C so my
outgoing interface and next hop would be the same as for B "
note that A, B, C are router here in case B is Transit network the next hop
is taken from C's Router LSA ( Link Data )

>
> 4.If we want the neighbor router can we take it directly from linkID of
> the parent
> or need to check the neighbor list of interface(that we get from
> linkdata)

not sure I understand your question, by neighbor router you mean the
neighbor router of the root ?( calculating router )
if the root is the parent of its neighbor router the outgoing interface is
taken from its Router LSA and the next hop if needed is found in the link
data field of its neighbor Router LSA.
note that you could have a neighbor router but the shortest path is through
a non direct path so the outgoing interface and next hop would be inherited
from its parent and the parent in this case is not the root

Sina

>
>
> Thanks in advance
>
> umesh

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