Figure 32 Router LSA format
Major fields of the Router LSA are as follows:
Link state ID: ID of the router that originated the LSA.
•
V (Virtual Link): Set to 1 if the router that originated the LSA is a virtual link endpoint.
•
E (External): Set to 1 if the router that originated the LSA is an ASBR.
•
B (Border): Set to 1 if the router that originated the LSA is an ABR.
•
•
# Links: Number of router links (interfaces) to the area, as described in the LSA.
Link ID: Determined by link type.
•
Link data: Determined by link type.
•
Type: Link type. A value of 1 indicates a point-to-point link to a remote router; a value of 2 indicates
•
a link to a transit network; a value of 3 indicates a link to a stub network; and a value of 4 indicates
a virtual link.
#TOS: Number of different TOS metrics given for this link. If no TOS metric is given for the link, this
•
field is set to 0. TOS is not supported in RFC 2328. The #TOS field is reserved for early versions of
OSPF.
•
Metric: Cost of using this router link.
TOS: IP Type of Service that this metric refers to.
•
•
TOS metric: TOS-specific metric information.
Network LSA
2.
A Network LSA is originated by the DR on a broadcast or NBMA network. The LSA describes all routers
attached to the network.
68