As per Relevance of the word references, we have this rfc below:
Network Working Group S.E. Hardcastle-
Requests for Comments 1275 University College
November 1991
Replication Requirements to provide an Internet Directory using X.500
Status of this
This memo provides information for the Internet community.
does not specify an Internet standard. Distribution of this
is unlimited
This RFCconsiders certain deficiencies of the 1988 X.500
standard, which need to be addressed before an effective
Internet Directory can be established using these protocols
services [CCI88]. The only areas considered are
problems, to which solutions must be found before a pilot can
deployed. This RFCconcerns itself with deficiencies which
only be addressed by use of additional protocol or procedures
distributed operation
RFC 1275 Replication Requirements November 1991
1 Distributed Operation
The Internet Directory will operate DSAs over TCP/IP using RFC 1006
[RC87], and DSAs over the an ISO Network Service.
operation procedures should not require full connectivity
2 Knowledge
Knowledge information is critical to resolution of names,
performing searches. Knowledge information high up the tree needs
be widely available. Consider resolving a name below ``Country=US''.
To do this, a DSA needs to have full knowledge at this point.
DSAs need to be able to do this, in order to give reasonable
and availability. It would be an unacceptable bottleneck to
such resolution to a single or small number of DSAs. To
this knowledge widely, a systematic approach to replication is needed
3 Data
Searches are often made at the root and country level, and this is
vital service (e.g., an approximate match of an organisation name).
Data needs to be collected in such a way that this sort of
is reasonably efficient. The usual X.500 approach of
references militates against this. At a node in the DIT,
references to the entries below are held. These entries will be
many DSAs, each of which needs to be accessed in order to perform
single level search. It is suggested that replication of data
necessary to achieve this
The major requirement for this replication is high up the DIT,
information must be replicated between different implementations.
lower levels of the DIT, it is reasonable for DSAs to be of the
implementation and to use implementation specific techniques in
to achieve performance and availability
4 Alternate
When a DSA Referral is returned, only the master DSA is indicated
This will lead to a single point of failure. It seems important
allow for additional references to slave copies, in order to
Hardcastle-Kille Page 1
RFC 1275 Replication Requirements November 1991
better availability. This needs to be solved in conjunction with
problem described in the previous section
5 Guidelines for use of
To be effective, the replication specification needs to
guidelines for deployment in the pilot, in order to meet the
service criteria
6 Some scaling
Most techniques for replication have scaling limits. It is
that mechanisms used do not stress the limits of the mechanism.
order of magnitude envisioned in the pilot is 100 000 non-leaf
and several million leaf entries
[CCI88] The Directory --- overview of concepts, models and services
December 1988. CCITT X.500 Series Recommendations
[RC87] Marshall T. Rose and Dwight E. Cass. ISO Transport
on top of the TCP. Request for Comments 1006,
Corporation Technology Center, May 1987.
7 Security
Security considerations are not discussed in this memo
8 Author's
Steve Hardcastle-
Department of Computer
University College
Gower
WC1E 6
Hardcastle-Kille Page 2
RFC 1275 Replication Requirements November 1991
Phone: +44-71-380-7294
EMail: S.Kille@CS.UCL.AC.
Hardcastle-Kille Page 3
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