Summary Link State Advertisements - 3Com 4007 Implementation Manual

Summary Link State
Advertisements
Area border routers can generate two types of summary link state
advertisements:
Summary link state advertisements that report the cost to a single
subnetwork number outside the area. These advertisements are
identified as Type 3 in the link state advertisement header.
Summary link state advertisements that report the cost to a single
autonomous system boundary router (ASBR). These advertisements
are identified as Type 4 in the link state advertisement header.
Each summary link state advertisement includes this information:
LSID (Link State ID) — Possible values:
For Type 3 summary link advertisements, this is the IP network
number.
For Type 4 summary link advertisements, this is the ASBR's
router ID.
Router ID — ID of the router that originated the LSA.
LS Seq (Link State Sequence) — The sequence number of the
advertisement. Used to detect old or duplicate link state
advertisements.
LS age — The time, in seconds, since the LSA was generated.
Network Mask — For Type 3 summary link state advertisements, this
is the destination network's IP address mask. For Type 4 summary link
state advertisements, this parameter is set to 0.
Metric — The cost of the specified route.
Link State Databases 477