A Distributed NHRP Service Using SCSP (RFC2335)
Original Publication Date: 1998-Apr-01
Included in the Prior Art Database: 2019-Feb-15
Internet Society Requests For Comment (RFCs)
This document describes a method for distributing an NHRP service within a LIS. [STANDARDS-TRACK]
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.
Luciani Standards Track [Page 1]
RFC 2335 NHRP Using SCSP April 1998
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 protocol.
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 independent specification.
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 initially written at the same time as SCSP, and thus a PID=0x0002 was assigned by the author.
SCSP places no topological requirements upon an...