... days¹

An article in the Sunday Times (19.12.1999) credited Linux with 14% of ``new servers'', versus 38% for Windows NT.

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... ISO²

ISO = International Standards Organisation.

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... ATM³

ATM = Asynchronous Transport Mode, a telephony-based system for long-distance large-scale networks.

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... TCP⁴

TCP = Transmission Control protocol: RFC 793, as updated by RFC 1122 and RFC2581.

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... UDP⁵

UDP = User Datagram Protocol: RFC 768, as updated by RFC 1122.

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... RPC⁶

RPC = Remote Procedure Call; originally a Sun implementation of a generic concept, but now an Internet RFC (1057).

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... XDR⁷

XDR = eXternal Data Representation; originally a SUN implementation, but now Internet RFC 1014 and 1832.

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... ANS.1/BER⁸

ASN.1 = Abstract Syntax Notation 1. BER = Basic Encoding Rules. These are in fact not Internet protocols, but were originally developed in ISO -- ISO 8824 (1987) in the case of ASN.1.

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... NFS⁹

NFS = Network File System; again originally a Sun implementation, but now Internet RFC 1094 (for NFS version 2), 1813 (for NFS version 3) and 3010 (RFC 3010 obsoleted the previous RFC 2624) (for NFS version 4). It has now (November 2003) been declared that 3010 obsoletes 1094 and 1813, but is itself obsoleted by RFC 3530.

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... medium¹⁰

More details about IP over ATM can be found in chapter 18 of Comer,D.E., Internetworking with TCP/IP vol. 1: Principles, Protocols and Architecture. 3rd. ed., Prentice-Hall, 1999.

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... RIPE¹¹

RIPE = Réseaux IP Européens = European IP Networks, a consortium of the major national networks in Europe.

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... address)¹²

This is the Class A address allocated to the original ARPAnet.

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... addresses)¹³

In use at Bath for IP addresses on the internal ``Classic IP'' network, and for ResNet and library docking points. For understanding how the latter accesses the wider Internet, see Appendix B.

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... as¹⁴

Notation is somewhat confused here: both 10/8 and 10/24 have been in use. 10/8 seems to be more common now, and is used in RFC1918. The ``official'' notation (RFC1518 and the various registries, is $<$address,mask$>$, as in <10.0.0.0,255.0.0.0>.

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... BWEMAN¹⁵

Bristol and West of England MAN. The main partners are the Universities of Bath, Bristol and West of England, and HP Laboratories in Bristol, but it also serves Bath Spa University College, Cheltenham and Gloucester College, the Higher Education Funding Council for England, and over a dozen further education colleges, as well as 150 schools via Bristol City Council.

BWEMAN is planning to merge with the network that serves Exeter, Plymouth etc. to form the South WEst Regional Network (SWERN).

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... Pipes''¹⁶

The ``fat pipe'' was the name for the one megabit-per-second (Mbps) link connecting JANET to the US' NSFNET in the early 1990s. Demand has mushroomed since then, and at the start of 1999 it was a 155Mbps link, and is now (March 2001) four such links, with a plan to move to a 2.5Gb link. For statistics on this link, see http://bill.ja.net.

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...10base2¹⁷

The length restriction was to be 200m, and the abbreviation stuck. Anyway, who would say 10base1.85?

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... UTP¹⁸

UTP = Unshielded Twisted Pair, i.e. telephone cable. CAT 5 UTP is the version commonly installed in buildings today. It has been estimated (http://www.grouper.ieee.org/groups/802/3/tutorial/march98/mick_170398.pdf) that 70% of all installed UTP is CAT 5, and the footage of CAT 5 installed is growing at 30% per annum.

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... products¹⁹

For more details, see Ferrero,A., The Eternal Ethernet. 2nd. ed., Addison-Wesley, 1999.

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... 100m²⁰

Or possibly 60m. And this seems to require the, as yet unpublished, CAT 6 version of UTP -- however, much CAT 5 seems to comply in practice. IEEE has now (2 June 1999) ratified IEEE 802.3ab, a standard for 1000baseT, which is Gigabit Ethernet over four pairs of CAT 5 wiring, up to 100m. It also allows auto-negotiation between 100Mbps and 1Gbps. See http://www.gigabit-ethernet.org/news/releases/062999.html.

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... IEEE²¹

Institute of Electrical and Electronics Engineers: www.ieee.org.

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... 802.2/802.3²²

IEEE 802.3 has been re-baptised as ISO 8802-3 (1990).

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... kept²³

IEEE 802.11, the standard for wireless Ethernets, says that the maximum length can be at most 2304 bytes (section 6.2.1.1.2).

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... fragmentation²⁴

See Chapter 11 for IP fragmentation.

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... irreducible²⁵

As a polynomial over the field with two elements, not just irreducible over the integers.

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... 2474²⁶

The terminology of RFC 2474 has been updated by RFC 3260.

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... unused²⁷

Though RFC 2481, now obsoleted by RFC 3168, describes an experimental use for them to indicate congestion. Section 19 of RFC 2474 contains a useful history of the TOS field.

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... (IPv4²⁸

RFC 2460 states that the IPv6 minimum MTU is 1280 bytes. See also http://www.psc.edu/~mathis/MTU/.

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... Margolin²⁹

Message Jj%V9.36$f83.1107@paloalto-snr1.gtei.net to comp.protocols.tcp-ip.

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... writes³⁰

Message b09i1m$dop$1@calcite.rhyolite.com to comp.protocols.tcp-ip.

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... LINX³¹

LINX = London INternet eXchange, routing packets between the Internet networks in the U.K. http://www.linx.net

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... TEN155³²

TEN155 was Trans-European Network at 155Mbps (though in fact the U.K.///Belgium ///Netherlands/France/Germany core now runs at 622Mbps), the replacement for the EBONE mentioned in the text. The current TEN155 diagram can be found at http:// www.dante.net/ten-155/ten155net.gif. TEN155 has itself been replaced by GÉANT, where the core (now U.K., France, Switzerland, Italy, Austria, Germany, Sweden) runs at 10Gbps: see http:// www.dante.net/geant. Notice also the curious fact in TEN155 that packets from Portugal to Spain go via the U.K., Belgium and France: this has been changed in GÉANT. However, in GÉANT, Israel is connected directly to the U.K., not via nearer countries such as Greece.

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... address³³

This cannot be detected in general, since most packets arrive with a level 2 address of some router, which is different from the Level 3 address of the true origin.

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... OSPF³⁴

But it does not necessarily have to participate in it? This is a somewhat curious requirement.

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... (1058³⁵

Updated by RFCs 1388, 1723 and 2453.

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... relationships''³⁶

RFC 2328, p. 193.

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... authentication³⁷

The currently defined ones are `null', `plain-text password' (which protects against a machine inadvertently joining an OSPF set-up), and `cryptographic authentication', which uses a password and the MD5 message digest to verify the authenticity of the packet. With cryptographic authentication, the checksum field is not used, since MD5 provides a far more powerful way of detecting corruption.

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...e164.arpa³⁸

Used for mapping telephone numbers: see RFCs 2916 and 3026.

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... some³⁹

cec.org is not the Commission of the European Community (this lives in eu.int), commonwealth.org is not the British Commonwealth, eea.org is the Edmonton Executives Association, not the European Economic Area, and www.nato.org is curious. The humorous might care to note that 3.1415926.org has joined the Internet

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....info⁴⁰

For example www.health-informatics.info.

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... mechanism⁴¹

In theory. In practice some DNS resolver implementations are unhappy with the character /, even though it is legal in the DNS (RFC 2181), and one should use a different character, e.g. -.

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... bytes⁴²

12 for the header, 23, 20, 34, 24 and 20 for the authority RRs, and 16 each for the additional RRs, since the names here have all occurred previously.

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... bytes⁴³

12 for the header, 29, 32, 40, 40 and 29 for the authority RRs, and 25, 28, 36, 36, and 25 for the additional RRs.

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... 2535⁴⁴

Note that the RSA/MD5 scheme in RFC 2537 (Algorithm code from RFC 2535 =1) has been obsoleted by the RSA/SHA-1 scheme in RFC 3110 (Algorithm code from RFC 2535 =5). RFC 2535 has also been updated by RFCs 3008, 3090 and 3226.

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... DHCP⁴⁵

DHCP = Dynamic Host Configuration Protocol.

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... posting⁴⁶

48babe1f.0208121808.37721440@posting.google.com to comp.protocols.tcp-ip.

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... header⁴⁷

Note the violation of the ``layering'' principle.

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... case⁴⁸

In theory IP options can also invalidate this assumption, but RFC 2525 states that ``Arguably, especially since the wide deployments of firewalls, IP options appear only rarely in normal operations.''

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... kernel⁴⁹

The command is ndd -set /dev/tcp tcp_sack_permitted 2. See http://www.psc.edu/networking/perf_tune.html

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... 2018⁵⁰

As updated by RFC 2883.

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... track⁵¹

According to RFC 3291. The latest edition of the RFC index (17 May 2002) still describes RFC 1441 etc. as ``Proposed Standard'', but that is a fairly weak statement.

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... (essentially)⁵²

The data is all in-band, marked with the escape character: however, the urgent pointer is sometimes set to help the other end see these data as soon as possible -- see segments 3 and 4 in Figure 26.17.

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... statistics⁵³

For 4 May 2001, 3250GB were received from North America, of which mail was 0.99%, FTP 4.98% and WWW at least 56.36%. For the whole of March 2001, 75Tbytes were received, with mail being 0.99% and FTP 5.54%.

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... usage⁵⁴

For example, in March 2001, the University of Bath had 1.89% mail of its 335Gb of traffic from the U.S. (and places relayed via the U.S., e.g. Australia). Conversely, Basingstoke College of Technology had only 0.46% mail, and their traffic was 92.34% Web.

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... PINE⁵⁵

PINE = Pine Is Not Elm, one of the self-referential jokes so common in the Unix world. It has largely replaced ELM as a Unix-based mailer.

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... protocols⁵⁶

The first POP RFC was 918 (1984); whereas the first IMAP RFC was 1064 (1988).

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... 3010⁵⁷

RFC 3010 obsoleted the previous RFC 2624, and is itself obsoleted by RFC 3530.

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... handle⁵⁸

Why have different layouts? Since the file handle is opaque, i.e. not meant to be read on the client, there is no reason to pass its contents through XDR (other than as a byte array). Hence the same C code, running on big-endian and little-endian machines, would actually generate different byte orders in the file handles.

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... WebNFS⁵⁹

Documented in RFCs 2054 and 2055.

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... clients⁶⁰

This scenario is taken from Ric Werne's post to comp.protocols.nfs -- message 9RTc4.2686$zU5.28853@wbnws01.ne.mediaone.net dated 5th. January 2000. He states ``Most Unixes have `close-to-open' consistency where an open will check the attributes on the server and invalidate the cache if the file is newer or a different size''.

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... systems.''⁶¹

Vernon Schryver (vjs@rhyolite.com) in news article a0c0g6$fg6$1@calcite.rhyolite.com.

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... 1.1⁶²

Defined in RFC 2616, which obsoletes RFC 2068 (which also described HTTP 1.1), and 2817.

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... NIS⁶³

NIS = Network Information Services. Sun used to call it ``Yellow Pages'' until a trademark law-suit was threatened by British Telecom. It provides shared user names/passwords etc. across a local area network, but has several security weaknesses.

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... protocol⁶⁴

RDP = Reliable Datagram Protocol, described in RFC 1151.

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... else⁶⁵

Initially. Soon an application gateway was installed to convert e-mail from SMTP-based TCP/IP mail to ``Yellow Book'' X.25-based e-mail (and vice versa) for communication with JANET, which at that point was running X.25 rather than TCP/IP.

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... cache⁶⁶

In theory, and as mandated by RFC 1122, such an entry should time out after 20 minutes, but, as pointed out on page 60, such timeouts tend to be, and on the Orions were, restarted each time the entry was used.

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