D-Link DES-3326SRM Product Manual - Page 180

Router Links Advertisements, Table 9. Routers Links Advertisement

Page 180 highlights

D-Link DES-3326S Layer 3 Switch 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: Routers Links Advertisements Link-State Age Options Link-State Type Link-State ID Advertising Router Link-State Sequence Number Link-State Checksum Length Reserved V E B Reserved Link ID Number of Links Link Data Type No. Of TOS TOS 0 Metric TOS 0 ... Metric TOS 0 ... Metric Link ID Link Data 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. Table 9. Routers Links Advertisement Field Description V - bit E - bit B - bit Number of Links 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. 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. Table 10. Routers Links Advertisements 170

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D-Link DES-3326S Layer 3 Switch
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:
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
V
B
E
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.
Table 9. Routers Links Advertisement
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.
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.
170
Table 10. Routers Links Advertisements