A Distributed NHRP Service Using SCSP (RFC2335)
Original Publication Date: 1998-Apr-01
Included in the Prior Art Database: 2000-Sep-13
Internet Society Requests For Comment (RFCs)
This document describes a method for distributing an NHRP service within a LIS . This method uses the Server Cache Synchronization Protocol (SCSP)  to synchronize the client information databases held by NHRP Servers (NHSs) within a LIS.
Network Working Group J. Luciani
Request for Comments: 2335 Bay Networks
Category: Standards Track April 1998
A Distributed NHRP Service Using SCSP
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (1998). All Rights Reserved.
This document describes a method for distributing an NHRP service
within a LIS . This method uses the Server Cache Synchronization
Protocol (SCSP)  to synchronize the client information databases
held by NHRP Servers (NHSs) within a LIS.
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
document, are to be interpreted as described in .
NHRP Clients (NHCs) register their existence and reachability
information with NHRP Servers (NHSs). There may be multiple NHSs in
a given Logical IP Subnet (LIS). NHCs do not necessarily register
with all NHSs in a LIS; however, all NHCs need to be able to query at
least one NHS about any NHC within the LIS. Thus, the contents of
the NHS databases in a LIS need to be synchronized across the LIS.
The Server Cache Synchronization Protocol (SCSP) solves the
generalized server synchronization/cache-replication problem for
distributed databases and thus SCSP may be applied to the NHS
database synchronization problem within the LIS.
SCSP is defined in two parts: the protocol independent part and the
client/server protocol specific part. The protocol independent part
is defined in  whereas this document will specify the
client/server protocol specific part where NHRP is the client/server
This document is separate from  because it was felt that it was
desirable to allow the client/server protocol specific part
specification for NHRP to progress independently from the protocol
All NHSs belonging to a Logical IP Subnet (LIS)  are said to
belong to a Server Group (SG). An SG is identified by, not
surprisingly, its SGID which is contained in a field in all SCSP
packets. All SCSP packets contain a Protocol ID (PID) field as well.
This PID field is set to 0x0002 to signify that SCSP synchronizing
NHS databases as opposed to synchronizing some other protocol's
databases (see Section B.2.0.1 of  for more details). In general,
PIDs for SCSP will be assigned by IANA as described in Section C of
. In the case of NHRP, the client/server protocol specific
specification was ...