Hi Zhang,

> 2)In Page 130, in section 12.4.1.1 Option 2, for IP
> numbered PTP link, If I can't get the peer address,
> which subnet will be assigned to the PTP link, my own
> or peer?
>

AFAIK this kind of situation should not arise. You will have the peer
address if you are fully adjacent to it.

>
> 3)why RFC don't discribe the Receiving the LSU packet
> and Send out the LSU packet, and now I am comfused
> about the receiving LSU? When I received a LSU, I need
> to send out a LSA packet?

As i understand, the question is whether we need to send an ACK back once we
recieve a LSU ?

Depends, upon the neighbor state. In exchange or loading i.e. when DBD
packets are being exchanged the LSR list contains a list of those LSAs which
are required from the neighbor. When the neighbor responds to these requests
with the proper LSUs , the LSR list is truncated and a new LSR list is sent.
LSAs on the LSR list that have been requested , but not yet recieved , are
packaged once again into the LSR list. Hence there are *no* explicit ACKs
sent for all the LSUs/LSAs recvd.

Consider the state when the neighbor state is full. LSU packets provide a
mechanism for flooding LSAs and *each* LSA must be acknowledged separately.
Hence there is *explicit* ACK sent now !

For each LSA contained in the LSU packet what all steps are taken is
explained in section 13. For any specific doubts, hammer them to this group
!

>
> 4)In Page 145, at the point (8), when received a LSU,
> the database copy LSA is more recent, I will send a
> LSU to neighbor, and that will make neighbor router
> NBR state machine to generate BadLSReq event,right?

BadLSReq is sent when a LSR is recieved for an LSA which does not exist !
If the database copy is newer than the one you recvd then simply send the
database copy back to the sender, encapsulated within a LSU packet.
What is the problem .. i guess i missed it !

>
> 5)In the Page 147, when installing the Router-LSAs and
> network-LSAs to the database, the entire routing table
> must be recalculated,the reason is that the AS
> boundary routers may belong to multiple areas.I can't
> understand this sentence,even the router belongs to
> multiple area, it can only run the SPF in one area and
> then generate the type 3 and 4 LSA to other areas, I
> think it is ok.

If a router belongs to multiple areas then it has to run SPF for *each* area
that it lies in !

I hope i'm clear.

Regards,
Manav

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