DES-6500 Chassis-based Layer 3 Ethernet Switch Manual
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Field
Description
Type
A quick classification of the router link. One of the following: Type
Description Point-to-point connection to another router. Connection to a
transit network. Connection to a stub network. Virtual link.
Link ID
Identifies the object that this router link connects to. Value depends on
the link’s Type. When connecting to an object that also originates a link
state advertisement (i.e. another router or a transit network) the Link ID is
equal to the neighboring advertisement’s Link State ID. This provides the
key for looking up an advertisement in the link state database. Type
Link ID Neighboring router’s Router ID. IP address of Designated Router.
IP network/subnet number. Neighboring router’s Router ID
Link Data
Contents again depend on the link’s Type field. For connections to stub
networks, it specifies the network’s IP address mask. For unnumbered
point-to-point connection, it specifies the interface’s MIB-II ifIndex value.
For other link types it specifies the router’s associated IP interface
address. This latter piece of information is needed during the routing
table build process, when calculating the IP address of the next hop.
No. of TOS
The number of different Type of Service (TOS) metrics given for this link,
not counting the required metric for TOS 0. If no additional TOS metrics
are given, this field should be set to 0.
TOS 0 Metric
The cost of using this router link for TOS 0.
For each link, separate metrics may be specified for each Type of Service (TOS). The metric for TOS 0 must always be
included, and was discussed above. Metrics for non-zero TOS are described below. Note that the cost for non-zero TOS
values that are not specified defaults to the TOS 0 cost. Metrics must be listed in order of increasing TOS encoding. For
example, the metric for TOS 16 must always follow the metric for TOS 8 when both are specified.
Field
Description
TOS
IP Type of Service that this metric refers to.
Metric
The cost of using this outbound router link, for traffic of the
specified TOS.
Network Links Advertisements
Network links advertisements are Type 2 link state advertisements. A network links advertisement is originated for each
transit network in the area. A transit network is a multi-access network that has more than one attached router. The network
links advertisement is originated by the network’s Designated router. The advertisement describes all routers attached to
the network, including the Designated Router itself. The advertisement’s Link State ID field lists the IP interface address of
the Designated Router.
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:
Summary of Contents for TM DES-6500
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