H3C Technologies H3C SR8800 - Manual (Page 63)

55
Frame relay address mapping
Frame relay address mapping associates the protocol address of a remote router with its frame relay
address (local DLCI). Through searching the frame relay address map by protocol address, the upper
layer protocol can locate a remote router. Frame relay can bear the IP protocol. When sending an IP
packet, the frame relay-enabled router can obtain its next hop address after consulting the routing table,
which is inadequate for sending the packet to the correct destination across a frame relay network. To
identify the DLCI of the next hop address, the router must search a frame relay address map retaining the
associations between remote IP addresses and next hop DLCIs.
A frame relay address map can be manually configured or maintained by Inverse Address Resolution
Protocol (InARP).
The following describes how frame relay uses InARP to create an address mapping:
Once a new virtual circuit is created, InARP sends an inverse ARP request over the circuit to request the
peer end for its protocol address. This request also conveys the local protocol address. When the peer
device receives the request, it creates an address mapping based on the protocol address in the request
and responds with its protocol address. When the local end receives the response, it creates the address
mapping for the peer.
For virtual circuits that have static address mappings, InARP will not be performed regardless of whether
the mappings are correct or not. In addition, the inverse ARP request recipient does not create a mapping
based on the protocol address in the request if a static entry is already available for the address.
Frame relay configuration task list
Complete the following tasks to configure frame relay:
Task Remarks
Configuring DTE side frame
relay
Configuring basic DTE side frame relay Required
Configuring frame relay address mappings Required
Configuring frame relay local virtual circuit Required
Configuring frame relay subinterface Optional
Configuring DCE side frame
relay
Configuring basic DCE side frame relay Required
Configuring frame relay address mapping Required
Configuring frame relay local virtual circuit Required
Configuring frame relay subinterface Optional
Enabling the trap function Optional
CAUTION:
•
Only PIC-ET32G2L sub-cards and POS sub-cards support Frame Relay.
• Before switching the link layer protocol of an interface (from PPP/HDLC to Frame Relay or the other way
around), manually remove all configurations related to QoS and ACL policies on the interface first.