Re: Initial LS Sequence Number

[Anand Oswal <aoswal at REDBACK.COM>]

Hi Gurpreet,

It doesnt mean that the router is not adhering to the spec.
The router state may have changed internally for the given area,
For a given interface the LSA will only be flooded when there
is atleast one neighbor in the exchange state or higher.

Hope that helps.
Thanks
Anand

"Singh, Gurpreet" wrote:
>
> Hi
> RFC 2328 Section 12.1.6
> "The sequence number -N (0x80000000) is reserved (and
> unused). This leaves -N + 1 (0x80000001) as the smallest
> (and therefore oldest) sequence number; this sequence number
> is referred to as the constant InitialSequenceNumber. A
> router uses InitialSequenceNumber the first time it
> originates any LSA. Afterwards, the LSA's sequence number
> is incremented each time the router originates a new
> instance of the LSA. "
> As stated above in the RFC 2328, a router should originate the first LSA to
> with InitialSequenceNumber. From the word originate i understand that the
> first LSA send by the router to its neighbor out of the physical interface.
> Is my assumption correct ?
> But i have observed that most of the OSPF implementations are not using the
> InitialSequenceNumber for the first Router LSA it originates when the router
> has just one neighbor and the OSPF process has been restarted to clear the
> database of the old LSAs. The first Router LSA routers sends has LS Sequence
> Number (1-5) higher than the InitialSequenceNumber.
> Should it be conlcuded that the router is not adhering to the Specifications
> if the LS Sequence number of the first Router LSA originated by router is
> not InitialSequenceNumber ?
> Thanks
> Gurpreet