D-Link DGS-3312SR [160/290] Autonomous s

D-Link DGS-3312SR [160/290] Autonomous s
DGS-3312SR Stackable Gigabit Layer 3 Switch
Link-State Age
Options
Link-State ID
Advertising Router
2
Link-State Sequence Number
Link-State Checksum
Length
Network Mask
Advertisements
TOS Metric
Summary Link
Figure 5- 28. Summary Link Advertisements
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.
Separate costs may be adverti st be included, and is always
or TOS 0 is described by the advertisement.
Otherwise, routes for the other TOS values are also described. ost for a certain TOS is not included, its cost defaults to
that specified for TOS 0.
sed for each IP Type of Service. Note that the cost for TOS 0 mu
listed first. If the T-bit is reset in the advertisement’s Option field, only a route f
If a c
Field Description
Network Mask
For Type 3 l
network’s IP
ink state advertisements, this indicates the destination
address mask. For example, when advertising the
location of a class A network the value 0xff000000
TOS
The Type of Service that the following cost is relevant to.
Metric
The cost of this route. Expressed in the same units as the interface
costs in the router links advertisements.
Autonomous S
Autonom
ystem
ous Systems (AS)
by AS boundary routers. A r each destination known to the router, that is external to the
AS.
isem
pecifies an IP netw
routes are used when no spe . When describing a default route, the Link Stat ID is always
set the Default Destination address (0.0.0.0) and the Network Mask is set to 0.0.0.0.
the AS Exter
s External Link Advertisements
link advertisements are Type 5 link state advertisements. These advertisements are originated
separate advertisement is made fo
AS external link advert
ID field s
ents usually describe a particular external destination. For these advertisements the Link State
ork number. AS external link advertisements are also used to describe a default route. Default
cific route exists to the destination
The format of nal Link Advertisement is shown below:
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