User manual

IP Routing Overview
Page 25-3
Transport Protocols
IP is both connectionless (it routes each datagram separately) and unreliable (it does not
guarantee delivery of datagrams). This means that a datagram may be damaged in transit, or
thrown away by a busy router, or simply never make it to its destination. The resolution of
these transit problems is to use a layer 4 transport protocol:
• Transmission Control Protocol (
TCP)—A major data transport mechanism that provides reli-
able, connection-oriented, full-duplex data streams. While the role of TCP is to add reliabil-
ity to IP, TCP relies upon IP to do the actual delivering of datagrams.
• User Datagram Protocol (
UDP)—A secondary transport-layer protocol that uses IP for deliv-
ery. However, UDP is not connection-oriented so it does not provide reliable end-to-end
delivery of datagrams. But some applications can safely use UDP to send datagrams that
don’t require the extra overhead added by TCP.
Application-Layer Protocols
• Bootstrap Protocol (BOOTP)/Dynamic Host Configuration Protocol (DHCP)—May be used
by an end station to obtain an IP address. The switch provides a UDP relay that allows
BOOTP requests/replies to cross different networks. See Chapter 26, “UDP Forwarding.”
• Simple Network Management Protocol (
SNMP)—Used to manage nodes on a network.
SNMP is discussed in Chapter 13, “Configuring SNMP.”
• Telnet—Used for remote connection to a device. The
telnet command is described in this
chapter.
• File Transfer Protocol (
FTP)—Enables transferring files between hosts.
Additional IP Protocols
• Internet Control Message Protocol (ICMP)—Specifies the generation of error messages, test
packets, and informational messages related to IP. ICMP supports the ping command used
to determine if hosts are online.
• Address Resolution Protocol (ARP)—Used to find the IP address that corresponds to a
given physical (
MAC) address.
• Internet Group Management Protocol (IGMP)—Tracks multicast group membership. See
the Multicast Services section of the Advanced Routing User Manual.
• Resource ReSerVation Protocol (RSVP)—Signals Quality of Service (QoS) requests in an IP
network. For more information, see the Switched Network Services User Manual.