D-Link xStack DGS-3600 User Manual page 155

Router Links Advertisements
Router links advertisements are type 1 link state advertisements. Each router in an area originates a routers links advertisement.
The advertisement describes the state and cost of the router's links to the area. All of the router's links to the area must be
described in a single router links advertisement.
The format of the Router Links Advertisement is shown below:
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
V - bit
E - bit
B - bit
Number of Links
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 network's IP address mask. For other link types, the Link Data specifies the router's associated IP interface
address.
xStack DGS-3600 Series Layer 3 Gigabit Ethernet Managed Switch
Routers Links Advertisements
Link-State Age
Link-State Sequence Number
Link-State Checksum
V E B
Reserved Reserved
Type No. Of TOS
TOS
0
...
0
TOS
Figure 8- 34. Routers Links Advertisements
Description
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).
When set, the router is an Autonomous System (AS) boundary router (E is for
External).
When set, the router is an area border router (B is for Border).
The number of router links described by this advertisement. This must be the
total collection of router links to the area.
Options
Link-State ID
Advertising Router
Length
Number of Links
Link ID
Link Data
TOS 0 Metric
Metric
Metric
...
Link ID
Link Data
139
Link-State Type