RFCs Recommended for Further Study

The RFCs selected for this list were chosen in a highly subjective and arbitrary fashion. Note, for example, that entire topics— such as the Simple Network Management Protocol (SNMP) and the Post Office Protocol (POP3)—have been omitted. Clearly, some topics had to be left out. Otherwise, this appendix would have been a rewrite of the index itself. RFCs that would help you build a solid technical foundation, as well as the RFCs that explained the inner workings of the Internet standards bodies, are included.

RFC 2235: Hobbes' Internet Timeline

This RFC provides a history of the major events that shaped the Internet into what it is today.

RFC 2200: Internet Official Protocol Standards

This RFC covers some of the processes involved in creating RFCs. It also explains some of the terms found in RFCs and their usage. This is a "must read" for anyone involved in supporting IP networks.

RFC 2151: A Primer on Internet and TCP/IP Tools and Utilities

This name is pretty self-explanatory. RFC 2151 is an introduction to some of the fundamental tools and utilities available. Traceroute, PING, Finger, and others are covered. This is another "must read."

RFC 2101: IPv4 Address Behavior Today

This RFC clarifies the current interpretation of the IP V4 32-bit IP address space. It also provides some background on IP V6.

RFC 2031: IETF-ISOC Relationship

This RFC explains the relationship between the IETF and the Internet Society.

RFC 2028: The Organizations Involved in the IETF Standards Process

This is pretty much what it says it is—an explanation of the organizations involved in the IETF standards process.

RFC 2027: IAB and IESG Selection, Confirmation, and Recall Process: Operation of the Nominating and Recall Committees

Again, this is pretty self-explanatory; it's an introduction to the process of selecting members for, and managing the membership of, the IAB and IESG.

RFC 2026: The Internet Standards Process: Revision 3

This is another RFC that explains RFC processes and other background information.

RFC 2008: Implications of Various Address Allocation Policies for Internet Routing

This RFC discusses some of the older policies for allocating IP address space. It suggests ways they can be changed to reflect the Internet changes that have occurred since they were originally drafted.

RFC 1935: What Is the Internet, Anyway?

An informational RFC discussing the Internet and what it means to different people and organizations.

RFC 1925: The Twelve Networking Truths

This is a humorous RFC about life and networking.

RFC 1923: RIPv1 Applicability Statement for Historic Status

This RFC discusses the current status of RIP V1 (RFC 1058) and some of its limitations. Anyone running a network with RIP V1 should read this.

RFC 1918: Address Allocation for Private Internets

This RFC provides background on the allocation of IP addresses for private Internets. It also provides implementation guidelines for companies that want to implement IP but do not want full connectivity to the Internet. This is a "must read" for anyone involved in supporting an IP network.

RFC 1917: An Appeal to the Internet Community to Return Unused IP Networks (Prefixes) to the IANA

This RFC discusses the limited amount of IP addresses available for allocation. It also explains how companies that have addresses they no longer require can return them.

RFC 1878: Variable Length Subnet Table for IPv4

This is a useful table of the various subnets that can be derived from the 32-bit IP address space.

RFC 1812: Requirements for IP Version 4 Routers

This RFC explains some of the functions that routers must perform when routing IP V4. This is a "must read" for anyone involved in supporting an IP network that uses routers.

RFC 1631: The IP Network Address Translator (NAT)

This RFC explains the function of IP address translation and some of the requirements that must be met by a device implementing NAT. This is a "must read" for anyone involved in supporting an IP network that uses NAT when accessing the Internet.

RFC 1601: Charter of the Internet ArchitectureBoard (IAB)

This is pretty self-explanatory; it is the charter of the IAB. Useful reading for anyone interested in the function of the IAB.

RFC 1580: Guide to Network Resource Tools

Similar to RFC 2151 in intent but not in content. This is more focused on information-finding tools, such as Gopher, WAIS, and USENET. This is a "must read" for anyone using the Internet to find or disseminate information.

RFC 1393: Traceroute Using an IP Option

This RFC provides background on the Traceroute utility. It also suggests some enhancements. This is useful reading for those responsible for troubleshooting IP network problems.

RFC 1256: ICMP Router Discovery Messages

This RFC explains IRDP and discusses how IP systems can use it to find and use IP gateways (routers) off of their local network. Some third-party TCP/IP stacks for Windows 95 and Windows NT support IRDP. SUN Solaris 2.5 does as well. Those exploring how to enable hosts to use multiple local gateways should read this.

RFC 1180: A TCP/IP Tutorial

This RFC is a solid introduction to the TCP/IP protocol suite. It discusses the multiplexing of various applications over TCP and UDP. It also explains some related applications, such as Telnet and FTP. This is a "must read" for anybody just getting started in implementing an IP-based network. Experienced IP support engineers may find some new information as well.

RFC 1178: Choosing a Name for Your Computer

This RFC covers some of the pitfalls of using inappropriate computer names and suggests some naming strategies.

RFC 1149: A Standard for the Transmission of IP Datagrams on Avian Carriers

This is another humorous RFC.

RFC 1058: Routing Information Protocol

This is "the" RFC for RIP V1. It is a "must read" for supporters of IP networks with routers because this is where it all started.

RFC 826: An Ethernet Address Resolution Protocol

This is the RFC on ARP. This is a "must read" for those involved in supporting IP networks.

RFC 1700: Assigned Numbers

This RFC contains references to the registered numbers that are assigned for various functions—such as TCP Port numbers for applications such as Telnet (23). Those involved in internetworking to any degree should be familiar with the material contained in this RFC.

RFC 1534: BOOTP

This RFC explains how certain TCP/IP configuration parameters, such as IP addresses, default gateways, and DNS servers, are passed from servers to workstations while the workstations are booting up. This allows network administrators to centralize the administration of this information. BOOTP has been superseded by the Dynamic Host Configuration Protocol (DHCP), which is referenced later in this appendix.

RFC 2283, RFC 1966, RFC 1965, RFC 1774, RFC 1773, RFC 1772, RFC 1771, RFC 1745: Border Gateway Protocol V4 (BGP4)

BGP4 is the latest version of this protocol. It specifies how routing information is passed between autonomous systems. Autonomous systems are groups of networks (which are typically very large) under the control of a single organization or a group of cooperating organizations. Internet Service Providers (ISPs) that control the backbone of the Internet typically have their own autonomous systems. ISPs use BGP to link these autonomous systems to other ISPs' autonomous systems.

For more information on this subject, see Internet Routing Architectures by Bassam Halabi, published by Cisco Press (ISBN 1-56205-652-2).

RFC 1817, RFC 1520, RFC 1519, RFC 1518, RFC 1517: Classless Interdomain Routing (CIDR)

CIDR replaces the standard network masks applied to classes of IP addresses. For example, instead of using a mask such as 255.255.0.0 for network 171.68.0.0, a mask of 255.0.0.0 could be applied. This would shorten the prefix of 171.68.0.0 to 171.0.0.0. If all of the networks that have 171 as their first octet were under the control of a single autonomous system, the autonomous system managers could limit their advertisements to other autonomous systems to an 8-bit prefix.

Instead of sending 16-bit prefixes, such as 171.1.0.0, 171.2.0.0, 171.2.0.0, and 171.253.0.0, to an adjacent autonomous system, the manager can just send 171.0.0.0. Because there are 254 possible 16-bit prefixes starting with 171.0.0.0, advertising can be saved on up to 253 networks (you still have to advertise 171.0.0.0), depending on how many of the available 171.0.0.0 networks are actually assigned.

The application of CIDR in the Internet has greatly reduced the numbers or routes (networks) that need to be advertised between and within autonomous systems.

RFC 2132, RFC 2131, RFC 1534: Dynamic Host Configuration Protocol (DHCP)

This RFC explains how certain TCP/IP configuration parameters, such as IP addresses, default gateways, and DNS servers, are passed from servers to workstations while the workstations are booting up. This allows network administrators to centralize the administration of this information. DHCP supersedes BOOTP, which was referenced previously.

RFC 2308, RFC 2230, RFC 2219, RFC 2182, RFC 2181, RFC 2136, RFC 2052, RFC 1996, RFC 1995, RFC 1912, RFC 1794, RFC 1713: Domain Name System (DNS)

This is the application that allows IP hosts to be referenced by names instead of explicit IP addresses. For instance, instead of entering c:ftp 192.31.7.130 to start a Windows FTP session to Cisco's FTP site, you can enter c:ftp ftp.cisco.com.

If your PC's DNS server(s) is configured properly, your PC sends a DNS query to its DNS server(s) (it can have more than one in case one fails) requesting the IP address associated with the system name ftp.cisco.com. After the reply is received, the FTP application uses the IP address it contains (192.31.7.130) to establish an FTP session.

RFC 2178, RFC 1745, RFC 1587, RFC 1586, RFC 1585, RFC 1584: Open Shortest Path First (OSPF)

These are the latest RFCs containing information on OSPF. OSPF is an open (not proprietary) standard. It is what is commonly known as an Interior Gateway Protocol (IGP). IGPs are typically used within autonomous systems. IGP was created to overcome some of the significant limitations of the Routing Information Protocol V1 (RIP), such as lack of VLSM support and lack of discontiguous network support.

RFC 1931, RFC 1293: Reverse Address Resolution Protocol (RARP) Inverse RARP

These protocols perform the opposite function of the Address Resolution Protocol (ARP). ARP maps layer three IP addresses to layer two MAC addresses. RARP, on the other hand, maps layer two MAC addresses to layer three IP addresses.

RFC 2092, RFC 2091, RFC 1723, RFC 1722, RFC 1721, RFC 1582, RFC 1581: RIP

RIP V1 was one of the original IP routing protocols. RIP V2, which is now available on many TCP/IP systems, overcomes some of the significant limitations of RIPV1, such as lack of VLSM support and lack of discontiguous network support. The RIP V1 protocol specification (RFC 1058) is provided in the previous section. The other RFCs refer to RIP V2 and other RIP enhancements.

RFC 2072, RFC 2071: Router Renumbering

These informational RFCs explain the concept of renumbering IP networks and indicate when this may be necessary.

RFC 2001: TCP/IP (TCP) Slow Start

TCP is the connection-oriented transport layer protocol in the TCP/IP protocol suite. It has flow control and error correction built in. It is used by TCP/IP applications, such as Telnet and FTP.

The TCP Slow Start algorithm forces a new TCP session to assume there is congestion on the network. This results in using a smaller packet size, a smaller window size (number of outstanding, unacknowledged packets), and a longer timeout (how long TCP will wait for acknowledgments before assuming a packet has been lost).

After the session is established, TCP starts increasing the packet size and the window size, while decreasing the timeout period. When TCP determines that the maximum values have been reached (the timeout period starts to expire for some packets), it reduces the packet sizes and the window, while increasing the timeout period. However, these numbers are not immediately dropped to their original Slow Start values.

RFC 1470: TCP/IP Debugging Tools

This RFC has valuable information on many tools and techniques for troubleshooting TCP/IP networking problems.