Network Working Group P. Jones
Request for Comments: 1346 Joint Network Team, UK
June 1992
Resource Allocation, Control, and Accounting
for the Use of Network Resources
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard. Distribution of this memo is
unlimited.
0. MANAGEMENT SUMMARY
This paper gives reasons for wanting better sharing mechanisms for
networks. It concludes that the challenge of sharing network
resources (and for example intercontinental link resources) between
groups of users is neither well understood, nor well catered for in
terms of tools for those responsible for managing the services. The
situation is compared with other fields, both inside and outside IT,
and examples are cited. Recommendations for further work are made.
The purpose of this RFC is to focus discussion on particular
challenges in large service networks in general, and the
International IP Internet in particular. No solution discussed in
this document is intended as a standard. Rather, it is hoped that a
general consensus will emerge as to the appropriate solutions,
leading eventually to the adoption of standards.
The structure of the paper is as follows:
1. Findings
2. Conclusions
3. Recommendations
1. FINDINGS
Issues arising from contention in the use of networks are not
unusual. Once connectivity and reliability have been addressed to a
reasonable level, bandwidth becomes (or appears to become?) the main
issue. Usage appears to have a strong tendency to rise to fill the
resources available (fully in line with the principles of Parkinson's
Law). Line-speed upgrades have an effect, but with no guarantee of
permanently alleviating the problem. Line-speeds are increasing as
technology improves over time, but the variations on matters like
availability and funding are wide, and users remain avaricious.
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Often the situation can appear worse than having to survive in a
jungle, in the sense that the strong (even if "good") seem to have
little advantage over the weak. It may seem that it is the
determined person rather than the important work that gets service.
Most people will have experienced poor service on an overloaded
network at some time. To help the end-users, it seems on the face of
it that one must help the IT Service Manager he relates to. Examples
relating to the relationship between the network manager and his
customers, IT Service Managers at institutions connecting to his
network, include the following:
(a) If the IT Service Manager finds his link to the Network Manager's
network overloaded, he may be offered a link upgrade, probably with a
cost estimate. He might prefer control mechanisms whereby he can say
that department X deserves more resources than department Y, or that
interactive terminal use takes preference over file transfers, or
that user U is more important than user V.
(b) Where an IT Service Manager is sharing a link, he will commonly
get more than his institution's share of the link, and often get very
good value-for-money compared to using a dedicated link, but he has
no guarantee that his end-users' usage won't get swamped by the use
of other (perhaps much larger) partners on the shared link. This
could be seen as wishing to have a guaranteed minimum share according
to some parameter(s).
(c) On a shared link as under (b), the Network Manager may wish to
ensure that usage of the link (which might be a high-performance
trunk line on a network or an international link for example) by any
one partner is "reasonable" in relation perhaps to his contribution
to the costs. In contrast to (b), the Network Manager is wishing to
impose a maximum value on some parameter(s). He may be happy if the
width of the IT Service Manager's access link is not greater than his
share of the shared link (assuming the measure agreed on is "width"),
but this will commonly not be the case. To be able to reach
agreement, the Network Manager and the IT Service Manager may need
options on the choice of parameters, and perhaps a choice on the
means of control, as well as being able to negotiate about values.
In circumstances where the Network Manager can exercise such controls
over his customers, the IT Service Managers may say with some feeling
and perhaps with justification, that if they are going to be
controlled can the Network Manager please provide tools whereby they
can arrange for the onward sharing of the resource they have, and
thence onwards down the hierarchy to the end-users.
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RFC 1346 Resource Allocation, Control, and Accounting June 1992
(d) It may be Network Manager A has a link that Network Manager B
would like to use on occasion, perhaps as back-up on access to a
third network. Network Manager A might well wish to be
accommodating, perhaps as examples because of financial benefit or
perhaps because of the possibility of a reciprocal arrangement.
However, the fear of overload affecting normal use and the lack of
control over the usage militates against arrangements that the
parties could be quite keen to make.
Such challenges are very far from being unique to networking.
Government and both public and private organisations and companies
allocate budgets (and resources other than money), control and
account for usage, recognising the possibility of overdrawing and
borrowing. In times of shortage, food is rationed. I haven't
checked this out, but it would surprise me if Jerry Hall wasn't
guaranteed a ticket for any Rolling Stones concert, should she wish
to attend.
The charging factor influences use but does not control it (except
perhaps in unusual circumstances where say payment was expected in
advance and usage was cut off when the money ran out).
In the IT world, multi-user hosts have filestore control systems; one
that I use has an overdraft facility with no penalty for not having a
prior arrangement! There are also system designs and implementations
for sharing host processor time with more sophistication than just
counting seconds and chopping people off; this problem seems to me to
be reasonably well understood. (Library catalogue searches under
author "John Larmouth" should provide some references for those who
require convincing.) Some multi-user hosts have controls of sorts on
terminal connections. On the other hand, I am not aware of any
control system in operation that can guarantee multi-user host
response time even outside the network context among directly
connected terminals.
The various roles bring different interests to bear. A provider will
not necessarily see it in his interests to control usage, or (perhaps
even more likely) to provide customers with control tools, since the
lack of these may encourage - or even oblige - the customer to buy
more. Even if the IT Service Manager can deal with the issue of who
or what is important, and the issues of the relative importance of
allocating resources against requests, other issues like social
acceptability may arise to complicate his life. For example it may
be generally agreed (and perhaps the network manager instructed) that
"everyone" must be able to do a small amount of work at any time,
perhaps to do some housekeeping or seek information.
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RFC 1346 Resource Allocation, Control, and Accounting June 1992
Time is an important factor. Network resources, like computer
processor time and unlike filestore, vanish if they are not used.
People will in general prefer resources during prime shift to those
in the middle of their night; however, in global terms the middle of
their night can be during prime shift somewhere along their path of
usage.
What's to do? Splitting lines with multiplexers is rather
inflexible, and may well militate against the benefits of resource-
sharing that give rise commonly to link-sharing arrangements. Some
technologies:
- have the ability to treat (or at least mark) traffic as of high
priority, for example where it gives emergency or status
information;
- (in the case of X.25(84), I understand from my JNT colleague Ian
Smith,) have throughput class (section 6.13) and transit delay
(section 6.27). (Ian tells me that it is in his view far from
clear how practical these facilities are);
- may be able to discriminate between traffic on grounds of
network source address;
- may be able to discriminate between traffic on grounds of
network destination address;
- may be able to discriminate between traffic on grounds of
application protocol, perhaps giving preference to interactive
terminal traffic, or making a choice between preference for
email and for file transfer traffic;
- may be able to discriminate between traffic on grounds of other
facets of network protocol or traffic.
In practice, one may well not have adequate tools in these or other
terms, and one may well have to ignore the challenges of resource
control, and either ignore the issue or refuse service.
2. CONCLUSIONS
2.1 There seems to be a lack of tools to enable the controlling
and the sharing of networks and links. This is militating against
the cooperative sharing of resources, and restricting the ability
of organisations to do business with one another.
2.2 Further, the definition of what constitutes a share, or what
parameter of service one would try to measure and control (or what
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the choices are if any), is not clear.
2.3 Following from that, it is then not clear whether what is
needed is new or enhanced protocols/services, new or enhanced
procurement specifications or profiles, or new or enhanced
networking products or tools.
2.4 Service providers (more likely the public carriers or but also
some Network Managers) may see it as against their interests to
provide controlling tools if they see them as tending to constrain
usage and hence reducing income. If so, they may not support, and
may even oppose, progress in the area. However, they might be
persuaded that the provision of such tools might give them
competitive edge over their rivals, and therefore to support
appropriate projects and developments.
3. RECOMMENDATIONS
There seems scope for one or more studies to:
- restate and refine the definition of the problems;
- collect, catalogue and relate relevant experience in both the
networking and non-networking fields;
- make recommendations as to what areas (e.g., among those
suggested in 2.3 above) projects should be undertaken;
- outline possible projects, indicating the timescale on which
improved sharing of production network service resources is
likely to be achieved, and recommending an order of priority
among the suggested projects.
FOOTNOTES:
Gender issues - where appropriate, the male embraces the female and
vice versa.
Dramatis Personae:
Jerry Hall is a close associate of Mr. M. Jagger, formerly of the
London School of Economics in the University of London, and now
Chairman and Chief Executive of an internationally prominent and
successful commercial musical operation.
Others mentioned in this paper are assumed to prefer to remain
anonymous, although the standard is to give contact information
for the author (see Author's Address section).
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Security Considerations
Security issues are not discussed in this memo.
Author's Address
Phil Jones
JNT
RAL, Chilton, Didcot, OXON OX11 0QX
Voice: +44-235-446618
Fax: +44-235-446251
Email: p.jones@jnt.ac.uk or c=gb;a= ;p=uk.ac;o=jnt;i=p;s=jones;
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