[j-nsp] Hello packets sending on NBMA netwroks

[zhuifeng0426]

Hi list:
I have a question about Hello packet sending on NBMA networks:
in page 79 of RFC 2328 it said:
"If the router is eligible to become Designated Router, it
must periodically send Hello Packets to all neighbors that
are also eligible.  In addition, if the router is itself the
Designated Router or Backup Designated Router, it must also
send periodic Hello Packets to all other neighbors."
and:
"If the router is not eligible to become Designated Router, 
it must periodically send Hello Packets to both the
Designated Router and the Backup Designated Router (if they
exist).  It must also send an Hello Packet in reply to an
Hello Packet received from any eligible neighbor (other than
the current Designated Router and Backup Designated Router).
This is needed to establish an initial bidirectional
relationship with any potential Designated Router."
so, here is a question:
since all eligible(other than DR and BDR) router won't send Hello packets to the router that is not eligible to become DR, how can these route reply the eligible(other than DR and BDR) router? 

2009-06-19 



zhuifeng0426