H3C Technologies H3C SecPath F1000-E - Manual (Page 29)

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Adjacency Table Configuration
This chapter includes these sections:
• Adjacency Table Overview
• Displaying and Maintaining Adjacency Table
NOTE:
•
Currently, the adjacency table feature only applies to hardware forwarding, but not software
forwarding.
• The adjacency table feature does not apply to Ethernet networks that use ARP for storing and managing
neighbor information.
Adjacency Table Overview
Introduction to Adjacency Table
An adjacency table manages information of the neighbors that are both connected and active. An
adjacency table maintains such information as neighbor network layer address (nexthop), route
outgoing interface, link layer service type, and link layer address (PVC for ATM; unavailable for PPP).
The concept of neighbor is relevant to network layer. Node B may be an IP neighbor, but not an IPX
neighbor of node A. Also, a neighbor in the active state is in relation to network layer. Currently, the
adjacency table feature only supports the neighbor concept in relation to IP.
A device can be connected with its neighbors through multiple link layer protocols, such as PPP, ATM and
FR (frame relay).
An adjacency table can be used for fast software forwarding in conjunction with the forwarding table.
The products supporting hardware forwarding can apply the adjacency table to the drivers to implement
hardware forwarding.
Terms
• Routing interface: Outgoing interface in a route entry.
• Physical interface: Such as serial interface, POS interface, and ATM interface.
• Logical interface: An abstract interface that does not correspond to any physical entity and is used
for adjacency table implementation, for example, Virtual-Ethernet interface, and Virtual-Template
interface.
• Service type: Type of service corresponding to the adjacency table, such as PPP and IP over ATM.
Currently, only PPP is supported.
• Action type: Action to take on the packet that matches the entry, forward or drop.