D-Link DGS-3612G Product Manual - Page 227

xStack® DGS-3600 Series Layer 3 Managed Gigabit Ethernet Switch 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: Network Link Advertisements Link-State Age Options 2 Link-State ID Advertising Router Link-State Sequence Number Link-State Checksum Length Network Mask Attached Router Figure 4- 47. Network Link Advertisements 211