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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.
2.
Network LSA
A Network LSA is originated by the DR on a broadcast or NBMA network. The LSA describes all routers
attached to the network.
