of their products. One of the most productive and rewarding ways
to do this on a long-term basis is to participate in ongoing
Internet research and development programs in partnership with the
academic community.
B.2. Interconnection Technology
In order to ensure network-level interoperability of different
vendor's gateways within the NSFNET context, we specify that a
gateway must at a minimum support Ethernet connections and serial
line protocol connections.
Currently the most important common interconnection technology
between Internet systems of different vendors is Ethernet. Among
the reasons for this are the following:
1. Ethernet specifications are well-understood and mature.
2. Ethernet technology is in almost all aspects vendor
independent.
3. Ethernet-compatible systems are common and becoming more
so.
RFC1009 - Requirements for Internet Gateways June 1987
These advantages combined favor the use of Ethernet technology as
the common point of demarcation between NSF network systems
supplied by different vendors, regardless of technology. It is a
requirement of NSF gateways that, regardless of the possibly
proprietary switching technology used to implement a given
vendor-supplied network, its gateways must support an Ethernet
attachment to gateways of other vendors.
It is expected that future NSF gateway requirements will specify
other interconnection technologies. The most likely candidates
are those based on X.25 or IEEE 802, but other technologies
including broadband cable, optical fiber, or other media may also
be considered.
B.3. Routing Interoperability
The Internet does not currently have an "open IGP" standard, i.e.,
a common IGP which would allow gateways from different vendors to
form a single Autonomous System. Several approaches to routing
interoperability are currently in use among vendors and the NSF
networking community.
* Proprietary IGP
At least one gateway vendor has implemented a proprietary IGP
and uses EGP to interface to the rest of the Internet.
* RIP
Although RIP is undocumented and various implementations of it
differ in subtle ways, it has been used successfully for
interoperation among multiple vendors as an IGP.
* Gateway Daemon
The NSF networking community has built a "gateway daemon"
program which can mediate among multiple routing protocols to
create a mixed-IGP Autonomous System. In particular, the
prototype gateway daemon executes on a 4.3BSD machine acting as
a gateway and exchanges routing information with other
gateways, speaking both RIP and Hello protocols; in addition,
it supports EGP to other Autonomous Systems.
RFC1009 - Requirements for Internet Gateways June 1987
B.4. Multi-Protocol Gateways
The present NSF gateway requirements specify only the Internet
protocol IP. However, in a few years the Internet will begin a
gradual transition to the functionally-equivalent subset of the
ISO protocols [17]. In particular, an increasing percentage of
the traffic will use the ISO Connectionless Mode Network Service
(CLNS, but commonly called "ISO IP") [33] in place of IP. It is
expected that the ISO suite will eventually become the dominant
one; however, it is also expected that requirements to support
Internet IP will continue, perhaps indefinitely.
To support the transition to ISO protocols and the coexistence
stage, it is highly desirable that a gateway design provide for
future extensions to support more than one protocol simultaneous,
and in particular both IP and CLNS [18].
Present NSF gateway requirements do not include protocols above
the network layer, such as TCP, unless necessary for network
monitoring or control. Vendors should recognize that future
requirements to interwork between Internet and ISO applications,
for example, may result in an opportunity to market gateways
supporting multiple protocols at all levels up through the
application level [16]. It is expected that the network-level NSF
gateway requirements summarized in this document will be
incorporated in the requirements document for these
application-level gateways.
Internet gateways function as intermediate systems (IS) with
respect to the ISO connectionless network model and incorporate
defined packet formats, routing algorithms and related procedures
[33, 34]. The ISO ES-IS [37] provides the functions of ARP and
ICMP Redirect.
B.5. Access Control and Accounting
There are no requirements for NSF gateways at this time to
incorporate specific access-control and accounting mechanisms in
the design; however, these important issues are currently under
study and will be incorporated into a subsequent edition of this
document. Vendors are encouraged to plan for the introduction of
these mechanisms into their products. While at this time no
definitive common model for access control and accounting has
emerged, it is possible to outline some general features such a
model is likely to have, among them the following:
RFC1009 - Requirements for Internet Gateways June 1987
1. The primary access control and accounting mechanisms will
be in the service hosts themselves, not the gateways,
packet-switches or workstations.
2. Agents acting on behalf of access control and accounting
mechanisms may be necessary in the gateways, to collect
data, enforce password protection, or mitigate resource
priority and fairness. However, the architecture and
protocols used by these agents may be a local matter and
cannot be specified in advance.
3. NSF gateways may be required to incorporate access control
and accounting mechanisms based on datagram
source/destination address, as well as other fields in the
IP header.
4. NSF gateways may be required to enforce policies on access
to gateway and communication resources. These policies may
be based upon equity ("fairness") or upon inequity
("priority").
RFC1009 - Requirements for Internet Gateways June 1987
Acknowledgments
An earlier version of this document (RFC-985) [60] was prepared by
Dave Mills in behalf of the Gateway Requirements Subcommittee of the
NSF Network Technical Advisory Group, in cooperation with the
Internet Activities Board, Internet Architecture Task Force, and
Internet Engineering Task Force. This effort was chaired by Dave
Mills, and contributed to by many people.
The authors of current document have also received assistance from
many people in the NSF and ARPA networking community. We thank you,
one and all.
RFC1009 - Requirements for Internet Gateways June 1987
References and Bibliography
Many of these references are available from the DDN Network
Information Center, SRI International, 333 Ravenswood Avenue, Menlo
Park, California 94025 (telephone: 800-235-3155).
[1] Postel, J., "Internet Protocol", RFC-791, USC Information
Sciences Institute, September 1981.
[2] Postel, J., "Internet Control Message Protocol", RFC-792, USC
Information Sciences Institute, September 1981.
[3] BBN, "Interface Message Processor - Specifications for the
Interconnection of a Host and an IMP", Report 1822, Bolt
Beranek and Newman, December 1981.
[4] Plummer, D., "An Ethernet Address Resolution Protocol",
RFC-826, Symbolics, September 1982.
[5] DOD, "Military Standard Internet Protocol", Military Standard
MIL-STD-1777, United States Department of Defense, August 1983.
[6] BBN, "Defense Data Network X.25 Host Interface Specification",
Report 5476, Bolt Beranek and Newman, December 1983.
[7] Hinden, R., "A Host Monitoring Protocol", RFC-869, BBN
Communications, December 1983.
[8] Korb, J.T., "A Standard for the Transmission of IP Datagrams
over Public Data Networks", RFC-877, Purdue University,
September 1983.
[9] Nagle, J., "Congestion Control in IP/TCP Internetworks",
RFC-896, Ford Aerospace, January 1984.
[10] Hornig, C., "A Standard for the Transmission of IP Datagrams
over Ethernet Networks", RFC-894, Symbolics, April 1984.
[11] Mills, D.L., "Exterior Gateway Formal Specification", RFC-904,
M/A-COM Linkabit, April 1984.
[12] Xerox, "Xerox Synchronous Point-to-Point Protocol", Xerox
System Integration Standard 158412, December 1984.
[13] Kirton, P., "EGP Gateway under Berkeley UNIX 4.2", RFC-911, USC
Information Sciences Institute, August 1984.
RFC1009 - Requirements for Internet Gateways June 1987
[14] Postel, J., "Multi-LAN Address Resolution", RFC-925, USC
Information Sciences Institute, October 1984.
[15] Finlayson, R., T. Mann, J. Mogul, and M. Theimer, "A Reverse
Address Resolution Protocol", RFC-904, Stanford University,
June 1984.
[16] NRC, "Transport Protocols for Department of Defense Data
Networks", RFC-942, National Research Council, March 1985.
[17] Postel, J., "DOD Statement on NRC Report", RFC-945, USC
Information Sciences Institute, April 1985.
[18] ISO, "Addendum to the Network Service Definition Covering
Network Layer Addressing", RFC-941, International Standards
Organization, April 1985.
[19] Leiner, B., J. Postel, R. Cole and D. Mills, "The DARPA
Internet Protocol Suite", Proceedings INFOCOM 85, IEEE,
Washington DC, March 1985. Also in: IEEE Communications
Magazine, March 1985. Also available as ISI-RS-85-153.
[20] Romkey, J., "PC/IP Programmer's Manual", MIT Laboratory for
Computer Science, pp. 57-59, April 1986.
[21] Mogul, J., and J. Postel, "Internet Standard Subnetting
Procedure", RFC-950, Stanford University, August 1985.
[22] Reynolds, J., and J. Postel, "Official Internet Protocols",
RFC-1011, USC Information Sciences Institute, May 1987.
[23] Reynolds, J., and J. Postel, "Assigned Numbers", RFC-1010, USC
Information Sciences Institute, May 1987.
[24] Nagle, J., "On Packet Switches with Infinite Storage", RFC-970,
Ford Aerospace, December 1985.
[25] SRI, "DDN Protocol Handbook", NIC-50004, NIC-50005, NIC-50006,
(three volumes), SRI International, December 1985.
[26] SRI, "ARPANET Information Brochure", NIC-50003, SRI
International, December 1985.
[27] Mills, D.L., "Autonomous Confederations", RFC-975, M/A-COM
Linkabit, February 1986.
[28] Jacobsen, O., and J. Postel, "Protocol Document Order
Information", RFC-980, SRI International, March 1986.
RFC1009 - Requirements for Internet Gateways June 1987
[29] Malis, A.G., "PSN End-to-End Functional Specification",
RFC-979, BBN Communications, March 1986.
[30] Postel, J, "Internetwork Applications using the DARPA Protocol
Suite", Proceedings INFOCOM 85, IEEE, Washington DC,
March 1985. Also available as ISI-RS-85-151.
[31] Postel, J, C. Sunshine, and D. Cohen, "The ARPA Internet
Protocol", Computer Networks, Vol. 5, No. 4, July 1981.
[32] Cerf, V., and R. Kahn, "A Protocol for Packet Network
Intercommunication", IEEE Transactions on Communication,
May 1974.
[33] ISO, "Protocol for Providing the Connectionless-mode Network
Service", RFC-994, DIS-8473, International Standards
Organization, March 1986.
[34] ANSI, "Draft Network Layer Routing Architecture", ANSI X3S3.3,
86-215R, April 1987.
[35] Rosen, E., "Exterior Gateway Protocol (EGP)", RFC-827, Bolt
Beranek and Newman, October 1982.
[36] Sidhu, D., "Some Problems with the Specification of the
Military Standard Internet Protocol", RFC-963, Iowa State
University, November 1985.
[37] ISO, "End System to Intermediate System Routing Exchange
Protocol for use in conjunction with ISO 8473", RFC-995,
April 1986.
[38] Postel, J., "Address Mappings", RFC-796, USC/Information
Sciences Institute, September 1981.
[39] Mills, D., "DCN Local Network Protocols", RFC-891, M/A-COM
Linkabit, December 1983.
[40] McQuillan, J. M., I. Richer, and E. C. Rosen, "The New Routing
Algorithm for the ARPANET", IEEE Transactions on
Communications, May 1980.
[41] Hinden, R., and A. Sheltzer, "The DARPA Internet Gateway",
RFC-823, Bolt Beranek and Newman, September 1982.
[42] Farber, D., G. Delp, and T. Conte, "A Thinwire Protocol for
Connecting Personal Computers to the Internet", RFC-914,
University of Delaware, September 1984.
RFC1009 - Requirements for Internet Gateways June 1987
[43] Mills, D., "Statistics Server", RFC-996, University Of
Delaware, February 1987.
[44] Postel, J. and K. Harrenstien, "Time Protocol", RFC-868,
May 1983.
[45] Mills, D., "Network Time Protocol (NTP)", RFC-958, M/A-Com
Linkabit, September 1985.
[46] Seamonson, L., and E. Rosen, "Stub Exterior Gateway Protocol",
RFC-888, Bolt Beranek And Newman, January 1984.
[47] Deering, S., and D. Cheriton, "Host Groups: A Multicast
Extension to the Internet Protocol", RFC-966, Stanford
University, December 1985.
[48] Deering, S., "Host Extensions for IP Multicasting", RFC-988,
Stanford University, July 1986.
[49] Mogul, J., "Broadcasting Internet Datagrams", RFC-919, Stanford
University, October 1984.
[50] Mogul, J., "Broadcasting Internet Datagrams in the Presence of
Subnets", RFC-922, Stanford University, October 1984.
[51] Rosen, E., "Exterior Gateway Protocol", RFC-827, Bolt Beranek
and Newman, October 1982.
[52] Rose, M., "Low Tech Connection into the ARPA Internet: The Raw
Packet Split Gateway", Technical Report 216, Department of
Information and Computer Science, University of California,
Irvine, February 1984.
[53] Rosen, E., "Issues in Buffer Management", IEN-182, Bolt Beranek
and Newman, May 1981.
[54] Rosen, E., "Logical Addressing", IEN-183, Bolt Beranek and
Newman, May 1981.
[55] Rosen, E., "Issues in Internetting - Part 1: Modelling the
Internet", IEN-184, Bolt Beranek and Newman, May 1981.
[56] Rosen, E., "Issues in Internetting - Part 2: Accessing the
Internet", IEN-187, Bolt Beranek and Newman, June 1981.
[57] Rosen, E., "Issues in Internetting - Part 3: Addressing",
IEN-188, Bolt Beranek and Newman, June 1981.
RFC1009 - Requirements for Internet Gateways June 1987
[58] Rosen, E., "Issues in Internetting - Part 4: Routing", IEN-189,
Bolt Beranek and Newman, June 1981.
[59] Sunshine, C., "Comments on Rosen's Memos", IEN-191, USC
Information Sciences Institute, July 1981.
[60] NTAG, "Requirements for Internet Gateways -- Draft", RFC-985,
Network Technical Advisory Group, National Science Foundation,
May 1986.
[61] Khanna, A., and Malis, A., "The ARPANET AHIP-E Host Access
Protocol (Enhanced AHIP)", RFC-1005, BBN Communications,
May 1987
[62] Nagle, J., "Congestion Control in IP/TCP Internetworks", ACM
Computer Communications Review, Vol.14, no.4, October 1984.