D-Link DGS-3312SR [159/290] N nks adver

D-Link DGS-3312SR [159/290] N nks adver
DGS-3312SR Stackable Gigabit Layer 3 Switch
N nks Adver
Network links advertisements
transit network in the area. A
links advertisement is origina o
the network, including the De
the Designated Router.
The distance form the networ
be specified in the network lin
The format of the Network Links Advert
etwork Li tisements
are Type 2 link state advertisements. A network links advertisement is originated for each
transit network is a multi-access network that has more than one attached router. The network
ted by the network’s Designated router. The advertisement describes all routers attached t
signated Router itself. The advertisement’s Link State ID field lists the IP interface address of
k to all attached routers is zero, for all TOS. This is why the TOS and metric fields need not
ks advertisement.
isement is shown below:
Link-State Age
Options
2
Link-State ID
Advertising Router
Link-State Sequence Number
Link-State Checksum
Length
Network Mask
Network Link Advertisements
Attached Router
Figure 5- 27. Network Link Advertisements
Field Description
Network Mask
The IP address mask for the network.
Attached Router
The Router Ids of each of the routers attached to the network. Only
those routers that are fully adjacent to the Designated Router (DR)
are listed. The DR includes itself in this list.
Summary Link Advertisements
Summary link advertisements are Type 3 and 4 link state advertisements. These advertisements are originated by Area
Border routers. A separate summary link advertisement is made for each destination known to the router, that belongs to
the Autonomous System (AS), yet is outside the area.
Type 3 link state advertisements are used when the destination is an IP network. In this case the advertisement’s Link State
ID field is an IP network number. When the destination is an AS boundary router, a Type 4 advertisement is used, and the
Link State ID field is the AS boundary router’s OSPF Router ID. Other that the difference in the Link State ID field, the
format of Type 3 and 4 link state advertisements is identical.
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