Cisco Systems 78-11741-02 Enabling Nhrp on an Interface, Statically Configuring a Next Hop Server

Configuring IP Addressing

Configuring Address Resolution Methods

Enabling NHRP on an Interface

To enable NHRP for an interface on a router, use the following command in interface configuration mode. In general, all NHRP stations within a logical NBMA network must be configured with the same network identifier.

Command	Purpose
Router(config-if)# ip nhrp network-idnumber	Enables NHRP on an interface.

See the “Logical NBMA Example” section and the “NHRP over ATM Example” section at the end of this chapter for examples of enabling NHRP.

Configuring a Static IP-to-NBMA Address Mapping for a Station

To participate in NHRP, a station connected to an NBMA network should be configured with the IP and NBMA addresses of its Next Hop Servers. The format of the NBMA address depends on the medium you are using. For example, ATM uses an NSAP address, Ethernet uses a MAC address, and SMDS uses an E.164 address.

These Next Hop Servers may also be the default or peer routers of the station, so their addresses can be obtained from the network layer forwarding table of the station.

If the station is attached to several link layer networks (including logical NBMA networks), the station should also be configured to receive routing information from its Next Hop Servers and peer routers so that it can determine which IP networks are reachable through which link layer networks.

To configure static IP-to-NBMA address mapping on a station (host or router), use the following command in interface configuration mode:

Command	Purpose
Router(config-if)# ip nhrp map ip-address	Configures static IP-to-NBMA address mapping.
nbma-address

Statically Configuring a Next Hop Server

A Next Hop Server normally uses the network layer forwarding table to determine where to forward NHRP packets, and to find the egress point from an NBMA network. A Next Hop Server may alternately be statically configured with a set of IP address prefixes that correspond to the IP addresses of the stations it serves, and their logical NBMA network identifiers.

To statically configure a Next Hop Server, use the following command in interface configuration mode:

Command	Purpose
Router(config-if)# ip nhrp nhs nhs-address	Statically configures a Next Hop Server.
[net-address [netmask]]

To configure multiple networks that the Next Hop Server serves, repeat the ip nhrp nhs command with the same Next Hop Server address, but different IP network addresses. To configure additional Next Hop Servers, repeat the ip nhrp nhs command.

Cisco IOS IP Configuration Guide

IPC-21