15. Packet Reordering
The Internet architecture does not guarantee that packets will arrive
in the same order in which they were originally transmitted;
transport protocols like TCP must take this into account.
However, reordering does come at a cost with TCP as it is currently
defined. Because TCP returns a cumulative acknowledgment (ACK)
indicating the last in-order segment that has arrived, out-of-order
segments cause a TCP receiver to transmit a duplicate acknowledgment.
When the TCP sender notices three duplicate acknowledgments, it
assumes that a segment was dropped by the network and uses the fast
retransmit algorithm [Jac90] [RFC2581] to resend the segment. In
addition, the congestion window is reduced by half, effectively
halving TCP's sending rate. If a subnetwork reorders segments
significantly such that three duplicate ACKs are generated, the TCP
sender needlessly reduces the congestion window and performance
Packet reordering frequently occurs in parts of the Internet, and it
seems to be difficult or impossible to eliminate [BPS99]. For this
reason, research on improving TCP's behavior in the face of packet
reordering [LK00] [BA02] has begun.
[BPS99] cites reasons why it may even be undesirable to eliminate
reordering. There are situations where average packet latency can be
reduced, link efficiency can be increased, and/or reliability can be
improved if reordering is permitted. Examples include certain high
speed switches within the Internet backbone and the parallel links
used over many Internet paths for load splitting and redundancy.
This suggests that subnetwork implementers should try to avoid packet
reordering whenever possible, but not if doing so compromises
efficiency, impairs reliability, or increases average packet delay.
Note that every header compression scheme currently standardized for
the Internet requires in-order packet delivery on the link between
compressor and decompressor. PPP is frequently used to carry
compressed TCP/IP packets; since it was originally designed for
point-to-point and dialup links, it is assumed to provide in-order
delivery. For this reason, subnetwork implementers who provide PPP
interfaces to VPNs and other more complex subnetworks, must also
maintain in-order delivery of PPP frames.
Internet users are increasingly mobile. Not only are many Internet
nodes laptop computers, but pocket organizers and mobile embedded
systems are also becoming nodes on the Internet. These nodes may
connect to many different access points on the Internet over time,
and they expect this to be largely transparent to their activities.
Except when they are not connected to the Internet at all, and for
performance differences when they are connected, they expect that
everything will "just work" regardless of their current Internet
attachment point or local subnetwork technology.
Changing a host's Internet attachment point involves one or more of
the following steps.
First, if use of the local subnetwork is restricted, the user's
credentials must be verified and access granted. There are many ways
to do this. A trivial example would be an "Internet cafe" that
grants physical access to the subnetwork for a fee. Subnetworks may
implement technical access controls of their own; one example is IEEE
802.11 Wireless Equivalent Privacy [IEEE80211]. It is common
practice for both cellular telephone and Internet service providers
(ISPs) to agree to serve one anothers' users; RADIUS [RFC2865] is the
standard method for ISPs to exchange authorization information.
Second, the host may have to be reconfigured with IP parameters
appropriate for the local subnetwork. This usually includes setting
an IP address, default router, and domain name system (DNS) servers.
On multiple-access networks, the Dynamic Host Configuration Protocol
(DHCP) [RFC2131] is almost universally used for this purpose. On PPP
links, these functions are performed by the IP Control Protocol
Third, traffic destined for the mobile host must be routed to its
current location. This roaming function is the most common meaning
of the term "Internet mobility".
Internet mobility can be provided at any of several layers in the
Internet protocol stack, and there is ongoing debate as to which is
the most appropriate and efficient. Mobility is already a feature of
certain application layer protocols; the Post Office Protocol (POP)
[RFC1939] and the Internet Message Access Protocol (IMAP) [RFC3501]
were created specifically to provide mobility in the receipt of
Mobility can also be provided at the IP layer [RFC3344]. This
mechanism provides greater transparency, viz., IP addresses that
remain fixed as the nodes move, but at the cost of potentially
significant network overhead and increased delay because of the sub-
optimal network routing and tunneling involved.
Some subnetworks may provide internal mobility, transparent to IP, as
a feature of their own internal routing mechanisms. To the extent
that these simplify routing at the IP layer, reduce the need for
mechanisms like Mobile IP, or exploit mechanisms unique to the
subnetwork, this is generally desirable. This is especially true
when the subnetwork covers a relatively small geographic area and the
users move rapidly between the attachment points within that area.
Examples of internal mobility schemes include Ethernet switching and
intra-system handoff in cellular telephony.
However, if the subnetwork is physically large and connects to other
parts of the Internet at multiple geographic points, care should be
taken to optimize the wide-area routing of packets between nodes on
the external Internet and nodes on the subnet. This is generally
done with "nearest exit" routing strategies. Because a given
subnetwork may be unaware of the actual physical location of a
destination on another subnetwork, it simply routes packets bound for
the other subnetwork to the nearest router between the two. This
implies some awareness of IP addressing and routing within the
subnetwork. The subnetwork may wish to use IP routing internally for
wide area routing and restrict subnetwork-specific routing to
constrained geographic areas where the effects of suboptimal routing
Subnetworks connecting more than two systems must provide their own
internal Layer-2 forwarding mechanisms, either implicitly (e.g.,
broadcast) or explicitly (e.g., switched). Since routing is the
major function of the Internet layer, the question naturally arises
as to the interaction between routing at the Internet layer and
routing in the subnet, and proper division of function between the
Layer-2 subnetworks can be point-to-point, connecting two systems, or
multipoint. Multipoint subnetworks can be broadcast (e.g., shared
media or emulated) or non-broadcast. Generally, IP considers
multipoint subnetworks as broadcast, with shared-medium Ethernet as
the canonical (and historical) example, and point-to-point
subnetworks as a degenerate case. Non-broadcast subnetworks may
require additional mechanisms, e.g., above IP at the routing layer
IP is ignorant of the topology of the subnetwork layer. In
particular, reconfiguration of subnetwork paths is not tracked by the
IP layer. IP is only affected by whether it can send/receive packets
sent to the remotely connected systems via the subnetwork interface
(i.e., the reachability from one router to another). IP further
considers that subnetworks are largely static -- that both their
membership and existence are stable at routing timescales (tens of
seconds); changes to these are considered re-provisioning, rather
Routing functionality in a subnetwork is related to addressing in
that subnetwork. Resolution of addresses on subnetwork links is
required for forwarding IP packets across links (e.g., ARP for IPv4,
or ND for IPv6). There is unlikely to be direct interaction between
subnetwork routing and IP routing. Where broadcast is provided or
explicitly emulated, address resolution can be used directly; where
not provided, the link layer routing may interface to a protocol for
resolution, e.g., to the Next-Hop Resolution Protocol [RFC2322] to
provide context-dependent address resolution capabilities.
Subnetwork routing can either complement or compete with IP routing.
It complements IP when a subnetwork encapsulates its internal
routing, and where the effects of that routing are not visible at the
IP layer. However, if different paths in the subnetwork have
characteristics that affect IP routing, it can affect or even inhibit
the convergence of IP routing.
Routing protocols generally consider Layer-2 subnetworks, i.e., with
subnet masks and no intermediate IP hops, to have uniform routing
metrics to all members. Routing can break when a link's
characteristics do not match the routing metric, in this case, e.g.,
when some member pairs have different path characteristics. Consider
a virtual Ethernet subnetwork that includes both nearby (sub-
millisecond latency) and remote (100's of milliseconds away) systems.
Presenting that group as a single subnetwork means that some routing
protocols will assume that all pairs have the same delay, and that
that delay is small. Because this is not the case, the routing
tables constructed may be suboptimal or may even fail to converge.
When a subnetwork is used for transit between a set of routers, it
conventionally provides the equivalent of a full mesh of point-to-
point links. Simplicity of the internal subnet structure can be used
(e.g., via NHRP [RFC2332]) to reduce the size of address resolution
tables, but routing exchanges will continue to reflect the full mesh
they emulate. In general, subnetworks should not be used as a
transit among a set of routers where routing protocols would break if
a full mesh of equivalent point-to-point links were used.
Some subnetworks have special features that allow the use of more
effective or responsive routing mechanisms that cannot be implemented
in IP because of its need for generality. One example is the self-
learning bridge algorithm widely used in Ethernet networks. Learning
bridges perform Layer-2 subnetwork forwarding, avoiding the need for
dynamic routing at each subnetwork hop. Another is the "handoff"
mechanism in cellular telephone networks, particularly the "soft
handoff" scheme in IS-95 CDMA.
Subnetworks that cover large geographic areas or include links of
widely-varying capabilities should be avoided. IP routing generally
considers all multipoint subnets equivalent to a local, shared-medium
link with uniform metrics between any pair of systems, and ignores
internal subnetwork topology. Where a subnetwork diverges from that
assumption, it is the obligation of subnetwork designers to provide
compensating mechanisms. Not doing so can affect the scalability and
convergence of IP routing, as noted above.
The subnetwork designer who decides to implement internal routing
should consider whether a custom routing algorithm is warranted, or
if an existing Internet routing algorithm or protocol may suffice.
The designer should consider whether this decision is to reduce the
address resolution table size (possible, but with additional protocol
support required), or is trying to reduce routing table complexity.
The latter may be better achieved by partitioning the subnetwork,
either physically or logically, and using network-layer protocols to
support partitioning (e.g., AS's in BGP). Protocols and routing
algorithms can be notoriously subtle, complex, and difficult to
implement correctly. Much work can be avoided if existing protocols
or implementations can be readily reused.
18. Security Considerations
Security has become a high priority in the design and operation of
the Internet. The Internet is vast, and countless organizations and
individuals own and operate its various components. A consensus has
emerged for what might be called a "security placement principle": a
security mechanism is most effective when it is placed as close as
possible to, and under the direct control of the owner of the asset
that it protects.
A corollary of this principle is that end-to-end security (e.g.,
confidentiality, authentication, integrity, and access control)
cannot be ensured with subnetwork security mechanisms. Not only are
end-to-end security mechanisms much more closely associated with the
end-user assets they protect, they are also much more comprehensive.
For example, end-to-end security mechanisms cover gaps that can
appear when otherwise good subnetwork mechanisms are concatenated.
This is an important application of the end-to-end principle [SRC81].
Several security mechanisms that can be used end-to-end have already
been deployed in the Internet and are enjoying increasing use. The
most important are the Secure Sockets Layer (SSL) [SSL2] [SSL3] and
TLS [RFC2246] primarily used to protect web commerce, Pretty Good
Privacy (PGP) [RFC1991] and S/MIME [RFCs-2630-2634], primarily used
to protect and authenticate email and software distributions, the
Secure Shell (SSH), used for secure remote access and file transfer,
and IPsec [RFC2401], a general purpose encryption and authentication
mechanism that sits just above IP and can be used by any IP
application. (IPsec can actually be used either on an end-to-end
basis or between security gateways that do not include either or both
Nonetheless, end-to-end security mechanisms are not used as widely as
might be desired. However, the group could not reach consensus on
whether subnetwork designers should be actively encouraged to
implement mechanisms to protect user data.
The clear consensus of the working group held that subnetwork
security mechanisms, especially when weak or incorrectly implemented
[BGW01], may actually be counterproductive. The argument is that
subnetwork security mechanisms can lull end users into a false sense
of security, diminish the incentive to deploy effective end-to-end
mechanisms, and encourage "risky" uses of the Internet that would not
be made if users understood the inherent limits of subnetwork
The other point of view encourages subnetwork security on the
principle that it is better than the default situation, which all too
often is no security at all. Users of especially vulnerable subnets
(such as consumers who have wireless home networks and/or shared
media Internet access) often have control over at most one endpoint
-- usually a client -- and therefore cannot enforce the use of end-
to-end mechanisms. However, subnet security can be entirely adequate
for protecting low-valued assets against the most likely threats. In
any event, subnet mechanisms do not preclude the use of end-to-end
mechanisms, which are typically used to protect highly-valued assets.
This viewpoint recognizes that many security policies implicitly
assume that the entire end-to-end path is composed of a series of
concatenated links that are nominally physically secured. That is,
these policies assume that all endpoints of all links are trusted,
and that access to the physical medium by attackers is difficult. To
meet the assumptions of such policies, explicit mechanisms are needed
for links (especially shared medium links) that lack physical
protection. This, for example, is the rationale that underlies Wired
Equivalent Privacy (WEP) in the IEEE 802.11 [IEEE80211] wireless LAN
standard, and the Baseline Privacy Interface in the DOCSIS [DOCSIS1]
[DOCSIS2] data over cable television networks standards.
We therefore recommend that subnetwork designers who choose to
implement security mechanisms to protect user data be as candid as
possible with the details of such security mechanisms and the
inherent limits of even the most secure mechanisms when implemented
in a subnetwork rather than on an end-to-end basis.
In keeping with the "placement principle", a clear consensus exists
for another subnetwork security role: the protection of the
subnetwork itself. Possible threats to subnetwork assets include
theft of service and denial of service; shared media subnets tend to
be especially vulnerable to such attacks. In some cases, mechanisms
that protect subnet assets can also improve (but cannot ensure) end-
One security service can be provided by the subnetwork that will aid
in the solution of an overall Internet problem: subnetwork security
should provide a mechanism to authenticate the source of a subnetwork
frame. This function is missing in some current protocols, e.g., the
use of ARP [RFC826] to associate an IPv4 address with a MAC address.
The IPv6 Neighbor Discovery (ND) [RFC2461] performs a similar
There are well-known security flaws with this address resolution
mechanism [Wilbur89]. However, the inclusion of subnetwork frame
source authentication will permit a secure subnetwork address.
Another potential role for subnetwork security is to protect users
against traffic analysis, i.e., identifying the communicating parties
and determining their communication patterns and volumes even when
their actual contents are protected by strong end-to-end security
mechanisms. Lower-layer security can be more effective against
traffic analysis due to its inherent ability to aggregate the
communications of multiple parties sharing the same physical
facilities while obscuring higher-layer protocol information that
indicates specific end points, such as IP addresses and TCP/UDP port
However, traffic analysis is a notoriously subtle and difficult
threat to understand and defeat, far more so than threats to
confidentiality and integrity. We therefore urge extreme care in the
design of subnetwork security mechanisms specifically intended to
thwart traffic analysis.
Subnetwork designers must keep in mind that design and implementation
for security is difficult [Schneier00]. [Schneier95] describes
protocols and algorithms which are considered well-understood and
believed to be sound.
Poor design process, subtle design errors and flawed implementation
can result in gaping vulnerabilities. In recent years, a number of
subnet standards have had problems exposed. The following are
examples of mistakes that have been made:
1. Use of weak and untested algorithms [Crypto9912] [BGW01]. For a
variety of reasons, algorithms were chosen which had subtle
flaws, making them vulnerable to a variety of attacks.
2. Use of "security by obscurity" [Schneier00] [Crypto9912]. One
common mistake is to assume that keeping cryptographic algorithms
secret makes them more secure. This is intuitive, but wrong.
Full public disclosure early in the design process attracts peer
review by knowledgeable cryptographers. Exposure of flaws by
this review far outweighs any imagined benefit from forcing
attackers to reverse engineer security algorithms.
3. Inclusion of trapdoors [Schneier00] [Crypto9912]. Trapdoors are
flaws surreptitiously left in an algorithm to allow it to be
broken. This might be done to recover lost keys or to permit
surreptitious access by governmental agencies. Trapdoors can be
discovered and exploited by malicious attackers.
4. Sending passwords or other identifying information as clear text.
For many years, analog cellular telephones could be cloned and
used to steal service. The cloners merely eavesdropped on the
registration protocols that exchanged everything in clear text.
5. Keys which are common to all systems on a subnet [BGW01].
6. Incorrect use of a sound mechanism. For example [BGW01], one
subnet standard includes an initialization vector which is poorly
designed and poorly specified. A determined attacker can easily
recover multiple ciphertexts encrypted with the same key stream
and perform statistical attacks to decipher them.
7. Identifying information sent in clear text that can be resolved
to an individual, identifiable device. This creates a
vulnerability to attacks targeted to that device (or its owner).
8. Inability to renew and revoke shared secret information.
9. Insufficient key length.
10. Failure to address "man-in-the-middle" attacks, e.g., with mutual
11. Failure to provide a form of replay detection, e.g., to prevent a
receiver from accepting packets from an attacker that simply
resends previously captured network traffic.
12. Failure to provide integrity mechanisms when providing
confidentiality schemes [Bel98].
This list is by no means comprehensive. Design problems are
difficult to avoid, but expert review is generally invaluable in
In addition, well-designed security protocols can be compromised by
implementation defects. Examples of such defects include use of
predictable pseudo-random numbers [RFC1750], vulnerability to buffer
overflow attacks due to unsafe use of certain I/O system calls
[WFBA2000], and inadvertent exposure of secret data.
This document represents a consensus of the members of the IETF
Performance Implications of Link Characteristics (PILC) working
This document would not have been possible without the contributions
of a great number of people in the Performance Implications of Link
Characteristics Working Group. In particular, the following people
provided major contributions of text, editing, and advice on this
document: Mark Allman provided the final editing to complete this
document. Carsten Bormann provided text on robust header
compression. Gorry Fairhurst provided text on broadcast and
multicast issues, routing, and many valuable comments on the entire
document. Aaron Falk provided text on bandwidth on demand. Dan
Grossman provided text on many facets of the document. Reiner Ludwig
provided thorough document review and text on TCP vs. Link-Layer
Retransmission. Jamshid Mahdavi provided text on TCP performance
calculations. Saverio Mascolo provided feedback on the document.
Gabriel Montenegro provided feedback on the document. Marie-Jose
Montpetit provided text on bandwidth on demand. Joe Touch provided
text on multicast, broadcast, and routing, and Lloyd Wood provided
many valuable comments on versions of the document.
20. Informative References
References of the form RFCnnnn are Internet Request for Comments
(RFC) documents available online at www.rfc-editor.org.
[802.1D] Information Technology Telecommunications and
information exchange between systems Local and
metropolitan area networks, Common specifications Media
access control (MAC) bridges, IEEE 802.1D, 1998. ISO
[802.1p] IEEE, 802.1p, Standard for Local and Metropolitan Area
Networks - Supplement to Media Access Control (MAC)
Bridges: Traffic Class Expediting and Multicast.
[AP99] Allman, M. and V. Paxson, On Estimating End-to-End
Network Path Properties, In Proceedings of ACM SIGCOMM
[AR02] Acar, G. and C. Rosenberg, Weighted Fair Bandwidth-on-
Demand (WFBoD) for Geo-Stationary Satellite Networks
with On-Board Processing, Computer Networks, 39(1),
[ATMFTM] The ATM Forum, "Traffic Management Specification,
Version 4.0", April 1996, document af-tm-0056.000.
[BA02] Blanton, E. and M. Allman, On Making TCP More Robust to
Packet Reordering. ACM Computer Communication Review,
32(1), January 2002.
[Bel98] Bellovin, S., "Cryptography and the Internet", in
Proceedings of CRYPTO '98, August 1998.
http://www.research.att.com/~smb/papers/inet-crypto.pdf[BGW01] Borisov, N., Goldberg, I. and D. Wagner, "Intercepting
Mobile Communications: The Insecurity of 802.11," In
Proceedings of ACM MobiCom, July 2001.
[BPK98] Balakrishnan, H., Padmanabhan, V. and R. Katz. "The
Effects of Asymmetry on TCP Performance." ACM Mobile
Networks and Applications (MONET), 1998.
[BPS99] Bennet,, J.C.R., Partridge, C. and N. Shectman, "Packet
Reordering is Not Pathological Network Behavior",
IEEE/ACM Transactions on Networking, Vol. 7, No. 6,
[CGMP] Farinacci D., Tweedly A. and T. Speakman, "Cisco Group
Management Protocol (CGMP)", 1996/1997.
ftp://ftpeng.cisco.com/ipmulticast/specs/cgmp.txt[Crypto9912] Schneier, B., "European Cellular Encryption Algorithms"
Crypto-Gram, December 15, 1999.
http://www.counterpane.com[DIX82] Digital Equipment Corp, Intel Corp, Xerox Corp,
Ethernet Local Area Network Specification Version 2.0,
[DOCSIS1] Data-Over-Cable Service Interface Specifications, Radio
Frequency Interface Specification 1.0, SP-RFI-I05-
991105, November 1999, Cable Television Laboratories,
[DOCSIS2] Data-Over-Cable Service Interface Specifications, Radio
Frequency Interface Specification 1.1, SP-RFIv1.1-I05-
000714, July 2000, Cable Television Laboratories, Inc.
[DOCSIS3] Lai, W.S., "DOCSIS-Based Cable Networks: Impact of
Large Data Packets on Upstream Capacity", 14th ITC
Specialists Seminar on Access Networks and Systems,
Barcelona, Spain, April 25-27, 2001.
[EN301192] ETSI, European Broadcasting Union, Digital Video
Broadcasting (DVB); DVB Specification for Data
Broadcasting, European Standard (Telecommunications
Series) EN 301 192 v1.2.1(1999-06).
[ES00] Eckhardt, D. and P. Steenkiste, "Effort-limited Fair
(ELF) Scheduling for Wireless Networks, Proceedings of
IEEE Infocom 2000.
[FB00] Firoiu V. and M. Borden, "A Study of Active Queue
Management for Congestion Control" to appear in Infocom
[GM02] Grieco1, L. and S. Mascolo, "TCP Westwood and Easy RED
to Improve Fairness in High-Speed Networks",
Proceedings of the 7th International Workshop on
Protocols for High-Speed Networks, April 2002.
[IEEE8023] IEEE 802.3 CSMA/CD Access Method.
http://standards.ieee.org/[IEEE80211] IEEE 802.11 Wireless LAN standard.
http://standards.ieee.org/[ISO3309] ISO/IEC 3309:1991(E), "Information Technology -
Telecommunications and information exchange between
systems - High-level data link control (HDLC)
procedures - Frame structure", International
Organization For Standardization, Fourth edition 1991-
[ISO13818] ISO/IEC, ISO/IEC 13818-1:2000(E) Information
Technology - Generic coding of moving pictures and
associated audio information: Systems, Second edition,
2000-12-01 International Organization for
Standardization and International Electrotechnical
[ITU-I363] ITU-T I.363.5 B-ISDN ATM Adaptation Layer Specification
Type AAL5, International Standards Organisation (ISO),
[Jac90] Jacobson, V., Modified TCP Congestion Avoidance
Algorithm. Email to the end2end-interest mailing list,
[KY02] Khafizov, F. and M. Yavuz, Running TCP Over IS-2000,
Proceedings of IEEE ICC, 2002.
[LK00] Ludwig, R. and R. H. Katz, "The Eifel Algorithm: Making
TCP Robust Against Spurious Retransmissions", ACM
Computer Communication Review, Vol. 30, No. 1, January
[LKJK02] Ludwig, R., Konrad, A., Joseph, A. D. and R. H. Katz,
"Optimizing the End-to-End Performance of Reliable
Flows over Wireless Links", Kluwer/ACM Wireless
Networks Journal, Vol. 8, Nos. 2/3, pp. 289-299,
[LRKOJ99] Ludwig, R., Rathonyi, B., Konrad, A., Oden, K. and A.
Joseph, Multi-Layer Tracing of TCP over a Reliable
Wireless Link, pp. 144-154, In Proceedings of ACM
[LS00] Ludwig, R. and K. Sklower, The Eifel Retransmission
Timer, ACM Computer Communication Review, Vol. 30, No.
3, July 2000.
[MAGMA-PROXY] Fenner, B., He, H., Haberman, B. and H. Sandick,
"IGMP/MLD-based Multicast Forwarding ("IGMP/MLD
Proxying")", Work in Progress.
[MAGMA-SNOOP] Christensen, M., Kimball, K. and F. Solensky,
"Considerations for IGMP and MLD Snooping Switches",
Work in Progress.
[MBB00] May, M., Bonald, T. and J-C. Bolot, "Analytic
Evaluation of RED Performance", INFOCOM 2000.
[MBDL99] May, M., Bolot, J., Diot, C. and B. Lyles, "Reasons not
to deploy RED", Proc. of 7th. International Workshop on
Quality of Service (IWQoS'99), June 1999.
[MSMO97] Mathis, M., Semke, J., Mahdavi, J. and T. Ott, "The
Macroscopic Behavior of the TCP Congestion Avoidance
Algorithm", Computer Communication Review, Vol. 27,
number 3, July 1997.
[MYR95] Boden, N., Cohen, D., Felderman, R., Kulawik, A.,
Seitz, C., et al. MYRINET: A Gigabit per Second Local
Area Network, IEEE-Micro, Vol. 15, No.1, February 1995,
[PFTK98] Padhye, J., Firoiu, V., Towsley, D. and J. Kurose,
"Modeling TCP Throughput: a Simple Model and its
Empirical Validation", UMASS CMPSCI Tech Report TR98-
008, Feb. 1998.
[RED93] Floyd, S. and V. Jacobson, "Random Early Detection
gateways for Congestion Avoidance", IEEE/ACM
Transactions in Networking, Vol. 1 No. 4, August 1993.
http://www.aciri.org/floyd/papers/red/red.html[RF95] Romanow, A. and S. Floyd, "Dynamics of TCP Traffic over
ATM Networks". IEEE Journal of Selected Areas in
Communication, Vol.13 No. 4, May 1995, p. 633-641.
[RFC791] Postel, J., "Internet Protocol", STD 5, RFC 791,
[RFC793] Postel, J., "Transmission Control Protocol", STD 7, RFC
793, September 1981.
[RFC768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
[RFC826] Plummer, D.C., "Ethernet Address Resolution Protocol:
Or converting network protocol addresses to 48-bit
Ethernet address for transmission on Ethernet
hardware", STD 37, RFC 826, November 1982.
[RFC1071] Braden, R., Borman, D. and C. Partridge, "Computing the
Internet checksum", RFC 1071, September 1988.
[RFC1112] Deering, S., "Host Extensions for IP Multicasting", STD
5, RFC 1112, August 1989.
[RFC1144] Jacobson, V., "Compressing TCP/IP Headers for Low-Speed
Serial Links", RFC 1144, February 1990.
[RFC1191] Mogul, J. and S. Deering, "Path MTU Discovery", RFC
1191, November 1990.
[RFC1332] McGregor, C., "The PPP Internet Protocol Control
Protocol (IPCP)", RFC 1332, May 1992.
[RFC1435] Knowles, S., "IESG Advice from Experience with Path MTU
Discovery", RFC 1435, March 1993.
[RFC1633] Braden, R., Clark, D. and S. Shenker, "Integrated
Services in the Internet Architecture: an Overview",
RFC 1633, June 1994.
[RFC1661] Simpson, W., "The Point-to-Point Protocol (PPP)", STD
51, RFC 1661, July 1994.
[RFC1662] Simpson, W., Ed., "PPP in HDLC-like Framing", STD 51,
RFC 1662, July 1994.
[RFC1750] Eastlake 3rd, D., Crocker, S. and J. Schiller,
"Randomness Recommendations for Security", RFC 1750,
[RFC1812] Baker, F., Ed., "Requirements for IP Version 4
Routers", RFC 1812, June 1995.
[RFC1939] Myers, J. and M. Rose, "Post Office Protocol - Version
3", STD 53, RFC 1939, May 1996.
[RFC1981] McCann, J., Deering, S. and J. Mogul, "Path MTU
Discovery for IP version 6", RFC 1981, August 1996.
[RFC1991] Atkins, D., Stallings, W. and P. Zimmermann, "PGP
Message Exchange Formats", RFC 1991, August 1996.
[RFC2018] Mathis, M., Mahdavi, J., Floyd, S. and A. Romanow, "TCP
Selective Acknowledgement Options", RFC 2018, October
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, March 1997.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S. and
S. Jamin, "Resource ReSerVation Protocol (RSVP) --
Version 1 Functional Specification", RFC 2205,
[RFC2208] Mankin, A., Baker, F., Braden, B., Bradner, S., O`Dell,
M., Romanow, A., Weinrib, A. and L. Zhang, "Resource
ReSerVation Protocol (RSVP) -- Version 1 Applicability
Statement Some Guidelines on Deployment", RFC 2208,
[RFC2210] Wroclawski, J., "The Use of RSVP with IETF Integrated
Services", RFC 2210, September 1997.
[RFC2211] Wroclawski, J., "Specification of the Controlled-Load
Network Element Service", RFC 2211, September 1997.
[RFC2212] Shenker, S., Partridge, C. and R. Guerin,
"Specification of Guaranteed Quality of Service", RFC
2212, September 1997.
[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version
1.0", RFC 2246, January 1999.
[RFC2309] Braden, B., Clark, D., Crowcroft, J., Davie, B.,
Deering, S., Estrin, D., Floyd, S., Jacobson, V.,
Minshall, G., Partridge, C., Peterson, L.,
Ramakrishnan, K., Shenker, S., Wroclawski, J. and L.
Zhang, "Recommendations on Queue Management and
Congestion Avoidance in the Internet", RFC 2309, April
[RFC2322] van den Hout, K., Koopal, A. and R. van Mook,
"Management of IP numbers by peg-dhcp", RFC 2322, 1
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April
[RFC2332] Luciani, J., Katz, D., Piscitello, D., Cole, B. and N.
Doraswamy, "NBMA Next Hop Resolution Protocol (NHRP)",
RFC 2332, April 1998.
[RFC2364] Gross, G., Kaycee, M., Li, A., Malis, A. and J.
Stephens, "PPP Over AAL5", RFC 2364, July 1998.
[RFC2394] Pereira, R., "IP Payload Compression Using DEFLATE",
RFC 2394, December 1998.
[RFC2395] Friend, R. and R. Monsour, "IP Payload Compression
Using LZS", RFC 2395, December 1998.
[RFC2401] Kent, S. and R. Atkinson, "Security Architecture for
the Internet Protocol", RFC 2401, November 1998.
[RFC2406] Kent, S. and R. Atkinson, "IP Encapsulating Security
Payload (ESP)", RFC 2406, November 1998.
[RFC2440] Callas, J., Donnerhacke, L., Finney, H. and R. Thayer,
"OpenPGP Message Format", RFC 2440, November 1998.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version
6 (IPv6) Specification", RFC 2460, December 1998.
[RFC2461] Narten, T., Nordmark, E. and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC 2461, December
[RFC2474] Nichols, K., Blake, S., Baker, F. and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, December 1998.
[RFC2507] Degermark, M., Nordgren, B. and S. Pink, "IP Header
Compression", RFC 2507, February 1999.
[RFC2508] Casner, S. and V. Jacobson, "Compressing IP/UDP/RTP
Headers for Low-Speed Serial Links", RFC 2508, February
[RFC2581] Allman, M., Paxson, V. and W. Stevens, "TCP Congestion
Control", RFC 2581, April 1999.
[RFC2582] Floyd, S. and T. Henderson, "The NewReno Modification
to TCP's Fast Recovery Algorithm", RFC 2582, April
[RFC2597] Heinanen, J., Baker, F., Weiss, W. and J. Wroclawski,
"Assured Forwarding PHB Group", RFC 2597, June 1999.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2630] Housley, R., "Cryptographic Message Syntax", RFC 2630,
[RFC2631] Rescorla, E., "Diffie-Hellman Key Agreement Method",
RFC 2631, June 1999.
[RFC2632] Ramsdell, B., Ed., "S/MIME Version 3 Certificate
Handling", RFC 2632, June 1999.
[RFC2633] Ramsdell, B., "S/MIME Version 3 Message Specification",
RFC 2633, June 1999.
[RFC2634] Hoffman, P., "Enhanced Security Services for S/MIME",
RFC 2634, June 1999.
[RFC2684] Grossman, D. and J. Heinanen, "Multiprotocol
Encapsulation over ATM Adaptation Layer 5", RFC 2684,
[RFC2686] Bormann, C., "The Multi-Class Extension to Multi-Link
PPP", RFC 2686, September 1999.
[RFC2687] Bormann, C., "PPP in a Real-time Oriented HDLC-like
Framing", RFC 2687, September 1999.
[RFC2689] Bormann, C., "Providing Integrated Services over Low-
bitrate Links", RFC 2689, September 1999.
[RFC2710] Deering, S., Fenner, W. and B. Haberman, "Multicast
Listener Discovery (MLD) for IPv6", RFC 2710, October
[RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D. and P.
Traina, "Generic Routing Encapsulation (GRE)", RFC
2784, March 2000.
[RFC2865] Rigney, C., Willens, S., Rubens, A. and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, June 2000.
[RFC2914] Floyd, S., "Congestion Control Principles", BCP 41, RFC
2914, September 2000.
[RFC2923] Lahey, K., "TCP Problems with Path MTU Discovery", RFC
2923, September 2000.
[RFC2988] Paxson, V. and M. Allman, "Computing TCP's
Retransmission Timer", RFC 2988, November 2000.
[RFC2990] Huston, G., "Next Steps for the IP QoS Architecture",
RFC 2990, November 2000.
[RFC3048] Whetten, B., Vicisano, L., Kermode, R., Handley, M.,
Floyd, S. and M. Luby, "Reliable Multicast Transport
Building Blocks for One-to-Many Bulk-Data Transfer",
RFC 3048, January 2001.
[RFC3095] Bormann, C., Ed., Burmeister, C., Degermark, M.,
Fukushima, H., Hannu, H., Jonsson, L-E., Hakenberg, R.,
Koren, T., Le, K., Liu, Z., Martensson, A., Miyazaki,
A., Svanbro, K., Wiebke, T., Yoshimura, T. and H.
Zheng, "RObust Header Compression (ROHC): Framework
and four profiles: RTP, UDP, ESP, and uncompressed",
RFC 3095, July 2001.
[RFC3096] Degermark, M., Ed., "Requirements for robust IP/UDP/RTP
header compression", RFC 3096, July 2001.
[RFC3150] Dawkins, S., Montenegro, G., Kojo, M. and V. Magret,
"End-to-end Performance Implications of Slow Links",
BCP 48, RFC 3150, July 2001.
[RFC3155] Dawkins, S., Montenegro, G., Kojo, M., Magret, V. and
N. Vaidya, "End-to-end Performance Implications of
Links with Errors", BCP 50, RFC 3155, August 2001.
[RFC3168] Ramakrishnan, K., Floyd, S. and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP", RFC
3168, September 2001.
[RFC3173] Shacham, A., Monsour, B., Pereira, R. and M. Thomas,
"IP Payload Compression Protocol (IPComp)", RFC 3173,
[RFC3246] Davie, B., Charny, A., Bennet, J.C.R., Benson, K., Le
Boudec, J.Y., Courtney, W., Davari, S., Firoiu, V. and
D. Stiliadis, "An Expedited Forwarding PHB (Per-Hop
Behavior)", RFC 3246, March 2002.
[RFC3248] Armitage, G., Carpenter, B., Casati, A., Crowcroft, J.,
Halpern, J., Kumar, B. and J. Schnizlein, "A Delay
Bound alternative revision of RFC 2598", RFC 3248,
[RFC3344] Perkins, C., Ed., "IP Mobility Support for IPv4", RFC
3344, August 2002.
[RFC3366] Fairhurst, G. and L. Wood, "Advice to link designers on
link Automatic Repeat reQuest (ARQ)", BCP 62, RFC 3366,
[RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B. and A.
Thyagarajan, "Internet Group Management Protocol,
Version 3", RFC 3376, October 2002.
[RFC3449] Balakrishnan, H., Padmanabhan, V., Fairhurst, G. and M.
Sooriyabandara, "TCP Performance Implications of
Network Path Asymmetry", BCP 69, RFC 3449, December
[RFC3450] Luby, M., Gemmell, J., Vicisano, L., Rizzo, L. and J.
Crowcroft, "Asynchronous Layered Coding (ALC) Protocol
Instantiation", RFC 3450, December 2002.
[RFC3451] Luby, M., Gemmell, J., Vicisano, L., Rizzo, L.,
Handley, M. and J. Crowcroft, "Layered Coding Transport
(LCT) Building Block", RFC 3451, December 2002.
[RFC3452] Luby, M., Vicisano, L., Gemmell, J., Rizzo, L.,
Handley, M. and J. Crowcroft, "Forward Error Correction
(FEC) Building Block", RFC 3452, December 2002.
[RFC3453] Luby, M., Vicisano, L., Gemmell, J., Rizzo, L.,
Handley, M. and J. Crowcroft, "The Use of Forward Error
Correction (FEC) in Reliable Multicast", RFC 3453,
[RFC3488] Wu, I. and T. Eckert, "Cisco Systems Router-port Group
Management Protocol (RGMP)", RFC 3488, February 2003.
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL -
VERSION 4rev1", RFC 3501, March 2003.
[RFC3828] Larzon, L-A., Degermark, M., Pink, S., Jonsson, L-E.,
Ed. and G. Fairhurst, Ed., "The User Datagram Protocol
(UDP)-Lite Protocol", RFC 3828, June 2004.
[Schneier95] Schneier, B., Applied Cryptography: Protocols,
Algorithms and Source Code in C (John Wiley and Sons,
[Schneier00] Schneier, B., Secrets and Lies: Digital Security in a
Networked World (John Wiley and Sons, August 2000).
[SP2000] Stone, J. and C. Partridge, "When the CRC and TCP
Checksum Disagree", ACM SIGCOMM, September 2000.
[SRC81] Saltzer, J., Reed D. and D. Clark, "End-to-End
Arguments in System Design". Second International
Conference on Distributed Computing Systems (April,
1981) pages 509-512. Published with minor changes in
ACM Transactions in Computer Systems 2, 4, November,
1984, pages 277-288. Reprinted in Craig Partridge,
editor Innovations in internetworking. Artech House,
Norwood, MA, 1988, pages 195-206. ISBN 0-89006-337-0.
[SSL2] Hickman, K., "The SSL Protocol", Netscape
Communications Corp., Feb 9, 1995.
[SSL3] Frier, A., Karlton, P. and P. Kocher, "The SSL 3.0
Protocol", Netscape Communications Corp., Nov 18, 1996.
[TCPF98] Lin, D. and H.T. Kung, "TCP Fast Recovery Strategies:
Analysis and Improvements", IEEE Infocom, March 1998.
tcp-final-198.pdf[WFBA2000] Wagner, D., Foster, J., Brewer, E. and A. Aiken, "A
First Step Toward Automated Detection of Buffer Overrun
Vulnerabilities", Proceedings of NDSS2000.
2000/proceedings/039.pdf[Wilbur89] Wilbur, Steve R., Jon Crowcroft, and Yuko Murayama.
"MAC layer Security Measures in Local Area Networks",
Local Area Network Security, Workshop LANSEC '89
Proceedings, Springer-Verlag, April 1989, pp. 53-64.
21. Contributors' Addresses
USC/Information Sciences Institute
4676 Admiralty Way
Marina Del Rey, CA 90292
Dipartimento di Elettrotecnica ed Elettronica,
Politecnico di Bari Via Orabona 4, 70125 Bari, Italy
Phone: +39 080 596 3621
Sun Microsystems Laboratories, Europe
180, Avenue de l'Europe
38334 Saint Ismier CEDEX
USC/Information Sciences Institute
4676 Admiralty Way
Marina del Rey CA 90292
Phone: 310 448 9151
9 New Square Park, Bedfont Lakes
Feltham TW14 8HA
Phone: +44 (0)20 8824 4236
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