There are two basic types of routing protocols: interior gateway protocols (IGPs), for routers within an autonomous system, and exterior gateway protocols (EGPs), for routers to communicate with routers in other autonomous systems.
The most popular IGP is the Routing Information Protocol (RIP) with OSPF being a newer IGP that is gaining widespread use. A new and popular EGP is the Border Gateway Protocol (BGP). In this chapter we
There are a two other OSI routing protocols that you may encounter. Interdomain Routing Protocol (IDRP) started out as a version of BGP modified for use with OSI addresses instead of IP. Intermediate System to Intermediate System Protocol (IS “IS) is the OSI standard IGP. It is used for routing CLNP (Connectionless Network Protocol), an OSI protocol similar to IP. IS-IS and OSPF are similar.
Dynamic routing is still a fertile area of internetworking research. The choice of which routing protocol to use, and which routing daemon to run, is complex. [Perlman 1992] provides many of the details.
In Figure 10.9 which of the routes came to gateway from the router kpno?
Assume a router has 30 routes to advertise using RIP, requiring one datagram with 25 routes and another with the remaining 5. What happens if once an
The OSPF packet format has a checksum field, but the RIP packet does not. Why?
What effect does load balancing, as done by OSPF, have on a transport layer?
Read RFC 1058 for additional details on the implementation of RIP. In Figure 10.8 each router advertises only the routes that it provides, and none of the other routes that it learned about through the other router's broadcasts on the 140.252.1 network. What is this technique called?
In Section 3.4 we said there are more than 100 hosts on the 140.252.1 subnet in addition to the eight routers we show in Figure 10.7. What do these 100
11.2 UDP Header
11.3 UDP Checksum
11.4 A Simple Example
11.5 IP Fragmentation
11.6 ICMP Unreachable Error (Fragmentation Required)
11.7 Determining the Path MTU Using Traceroute
11.8 Path MTU Discovery with UDP
11.9 Interaction Between UDP and ARP
11.10 Maximum UDP Datagram Size
11.11 ICMP Source Quench Error
11.12 UDP Server Design
UDP is a simple, datagram-oriented, transport layer protocol: each output operation by a process produces exactly one UDP datagram, which causes one IP datagram to be sent. This is different from a stream-oriented protocol such as TCP where the amount of data written by an application may have little relationship to what actually gets sent in a single IP datagram.
Figure 11.1 shows the encapsulation of a UDP datagram as an IP datagram.
RFC 768 [Postel 1980] is the official specification of UDP.
UDP provides no reliability: it sends the datagrams that the application
The application needs to worry about the
Internetworking with TCP/IP Vol.1: Principles, Protocols, and Architecture (4th Edition)
Unix Network Programming, Volume 1: The Sockets Networking API (3rd Edition)
TCP/IP Illustrated, Vol. 2: The Implementation
TCP/IP Illustrated, Vol. 3: TCP for Transactions, HTTP, NNTP, and the UNIX Domain Protocols