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DES-3326 Layer 3 Fast Ethernet Switch User’s Guide
Link-State Age
Options Link-State Type
Link-State ID
Advertising Router
Link-State Sequence Number
Link-State Checksum
Length
Routers Links Advertisements
Reserved Reserved Number of Links
Link ID
Link Data
Type No. Of TOS TOS 0 Metric
TOS
Metric
...
TOS
Metric
...
Link ID
Link Data
0
0
VBE
Figure 5-33. Routers Links Advertisement
In router links advertisements, the Link State ID field is set to the router’s OSPF Router ID. The T – bit
is set in the advertisement’s Option field if and only if the router is able to calculate a separate set of
routes for each IP Type of Service (TOS). Router links advertisements are flooded throughout a single
area only.
Field Description
V – bit When set, the router is an endpoint of an active
virtual link that is using the described area as a
Transit area (V is for Virtual link endpoint).
E – bit When set, the router is an Autonomous System
(AS) boundary router (E is for External).
B – bit When set, the router is an area border router (B is
for Border).
Number of Links The number of router links described by this
advertisement. This must be the total collection of
router links to the area.
Table 5-17. Routers Links Advertisement
The following fields are used to describe each router link. Each router link is typed. The Type field
indicates the kind of link being described. It may be a link to a transit network, to another router or to
a stub network. The values of all the other fields describing a router link depend on the link’s Type. For
example, each link has an associated 32-bit data field. For links to stub networks this field specifies the
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