159Displaying the adjacency tableThe adjacency table stores information about directly connected neighbors for IP forwarding. Theneighbor information in the adjacency table in this chapter refers to non-Ethernet neighbor information.This table is not user configurable. The neighbor information is generated, updated, and deleted by linklayer protocols through negotiation (such as PPP dynamic negotiation) or through manual configuration(such as ATM static configuration). An adjacency entry contains the neighbor network layer address(next hop), output interface, link layer protocol type, and link layer address (PVC for ATM, unavailablefor PPP).When forwarding an IP packet, the device searches the FIB to find the output interface and next hop, andthen uses the output interface and next hop address to search the adjacency table for link layerforwarding information that is required for forwarding the packet.NOTE:Ethernet neighbor information and non-Ethernet neighbor information are stored and managed together.The following table shows the items contained in an adjacency table output:Item DescriptionIP address IP address of the next hop in FIB table for packet forwarding. This address isused for adjacency table lookup.Routing interface Output interface in the matching route entry. This interface is used foradjacency table lookup, and it can be logical or physical.Physical interfaceOutput physical interface that sends matching packets. If the routing interfaceis physical, the routing interface and physical interface are the same. If therouting interface is logical, the routing interface and physical interface aredifferent.Logical interface Logical interface for sending packets, such as a virtual-Ethernet interface forATM, or a Virtual-Template interface for MP.Service type Link layer protocol type, such as PPP or HDLC.Action type Action to be taken on the matching packet: Forwarding or Drop.Link media type Related to the link layer protocol used by the routing interface. P2P indicatesa point-to-point link and NBMA indicates a non-broadcast multi-access link.Link head information(IP) Link layer header for IP forwarding.Link head information(IPv6) Link layer header for IPv6 forwarding.Link head information(MPLS) Link layer header for MPLS forwarding.To display adjacency table entries, use one of the following commands as appropriate in any view:Task CommandDisplay IPv4 adjacency tableinformation.display adjacent-table { all | physical-interface interface-typeinterface-number | routing-interface interface-typeinterface-number | slot slot-number } [ count | verbose ]
