3Com Switch 4800G 24-Port Configuration Manual page 288

288 C 28: OSPF C
HAPTER ONFIGURATION
Formats of LSAs
1 Router LSA
Figure 88 Router LSA format
0
LS checksum
0 V E B
Type
TOS
Major fields:
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, described in the LSA.
■
Link ID: Determined by Link type.
■
Link Data: Determined by Link type.
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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; a value of 4 indicates a virtual link.
#TOS: Number of different TOS metrics given for this link.
■
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
■
A Network LSA is originated by the DR on a broadcast or NBMA network. The LSA
describes all routers attached to the network.
7 15
LS age
Linke state ID
Advertising Router
LS sequence number
0
Link ID
Link data
#TOS
0
Link ID
Link data
Options
Length
# links
metric
...
TOS metric
...
31
1