Avaya Configuring MPOA Services Manual do Utilizador descarregar pdf (Página 27)

Understanding MPOA and NHRP

309249-14.00 Rev 00

1-7

NHRP

NHRP is an address resolution protocol described in Internet RFC 2332.

As defined by the RFC, NHRP provides address resolution services by mapping

“internetworking layer addresses to NBMA subnetwork addresses.” As

implemented by Nortel Networks, NHRP resolves IP to ATM addresses.

The IETF draft specifies behavior for NHRP clients and NHRP servers.

• The NHRP client (NHC) generates NHRP address resolution requests on

behalf of applications such as a local MPS.

• The NHRP server (NHS) responds to NHRP address resolution requests by

generating NHRP address resolution replies. For this purpose, the NHS

maintains a next-hop cache.

NHRP supports address resolution using seven formatted message types.

• NHRP resolution request

An NHRP resolution request is generated by an NHC and routed through the

ATM topology. Functionally equivalent to a standard ARP request, it contains

the layer 3 and layer 2 address of the originator, the layer 3 address of the

target destination, and a blank field reserved for the layer 2 address of the

target. As implemented by Nortel Networks, the NHRP resolution request

contains the IP and ATM addresses of the originator and the IP address of the

target.

• NHRP resolution reply

An NHRP resolution reply is generated by an NHS in response to an NHRP

resolution request. Like an NHRP resolution request, it is routed through the

ATM topology. It is functionally equivalent to a standard ARP response in that

it replicates the information in the NHRP resolution request and supplies the

requested layer 2 (ATM) address.

• NHRP registration request

An NHRP registration request is generated by an NHC and directed toward

the local NHS. The NHRP registration request is used to register address

mapping data gathered by the NHC with the NHS. The NHS places mapping

data in its next-hop cache.

1 2 ... 22 23 24 25 26 27 28 29 30 31 32 ... 147 148

Sem comentários

Avaya Configuring MPOA Services Manual do Utilizador Página 27