D-Link DES-3326 manual Routers Links Advertisement

DES-3326 Layer 3 Fast Ethernet Switch User’s Guide

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	Number of Links
	Link ID
	Link Data
Type	No. Of TOS	TOS 0 Metric
TOS	0	Metric
	...
TOS	0	Metric
	...

Link ID

Link Data

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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