D-Link DGS-3312SR [157/290] Router links advertisements

D-Link DGS-3312SR [157/290] Router links advertisements
DGS-3312SR Stackable Gigabit Layer 3 Switch
Router Links Advertisements
Router links advertisements are ty an area originates a routers links
the area. All of the router’s links to
isement is shown below:
pe 1 link state advertisements. Each router in
advertisement. The advertisement describes the state and cost of the router’s links to
the area must be described in a single router links advertisement.
The format of the Router Links Advert
Link-State Age
Options Link-State Type
Link-State ID
Advertising Router
ers Links Advertisements
Link ID
Link Data
Type No. Of TOS TOS 0 Metric
TOS
Metric
...
TOS
Metric
...
Link ID
Link Data
0
0
Link-State Sequence Number
Link-State Checksum
Length
Rout
Reserved Reserved Number of Links
VBE
Figure 5- 26. 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.
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.
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