D-Link DGS-3312SR Product Manual page 121

The distance form the network to all attached routers is zero, for all TOS. This is why the TOS and metric fields need not
be specified in the network links advertisement.
The format of the Network Links Advertisement is shown below:
Field
Network Mask
Attached Router
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.
For stub area, Type 3 summary link advertisements can also be used to describe a default route on a per-area basis. Default
summary routes are used in stub area instead of flooding a complete set of external routes. When describing a default
summary route, the advertisement's Link State ID is always set to the Default Destination − 0.0.0.0, and the Network Mask
is set to 0.0.0.0.
DGS-3312SR Gigabit Layer 3 Switch
Network Link Advertisements
Link-State Age
Link-State ID
Advertising Router
Link-State Sequence Number
Link-State Checksum
Network Mask
Attached Router
Figure 5- 16. Network Link Advertisements
Description
The IP address mask for the network.
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
Link-State Age
Link-State ID
Advertising Router
Link-State Sequence Number
Link-State Checksum
Network Mask
TOS
Figure 5- 17. Summary Link Advertisements
Options
Length
Options
Length
Metric
108
2
2