must be ensured by a higher level protocol, such as TCP.Integral to every IP
implementation is the Internet Control Message Protocol (ICMP), which is used for
reporting errors, congestion reporting, and first-hop router redirection.
Internet Control Message Protocol
The Internet Control Message Protocol (ICMP) provides for error and control
messages between host systems (peer computers in a network) and routers.
Routers and host systems use ICMP to send reports of problems. ICMP also
includes an echo request or reply message that is used to test whether a
destination can be reached and is responding. This is commonly known as PING
(Packet InterNet Groper).
Internet Group Management Protocol
The Internet Group Management Protocol (IGMP) is used by IP hosts to report their
host group memberships to neighboring multicast routers. Multicast routers send
Host Membership Query messages to discover which host groups have members
on their attached networks. Hosts respond to a Query by generating Host
Membership Reports, reporting each host group to which they belong. The multicast
routers use this information to determine where multicast datagrams need to be
forwarded.
Address Resolution Protocol
The Address Resolution Protocol (ARP) dynamically associates internet addresses
to physical hardware addresses on a local network. ARP relies on the broadcast
capabilities of the underlying media to provide this function.
AnyNet/400
AnyNet/400 is part of the AnyNet family of products.AnyNet products allow
application programs written for one communications protocol to run over non-native
protocols without changing (or recompiling) the application programs. The
destination address determines if the request is sent over the native protocol or
through the AnyNet code and on to a non-native protocol.
AnyNet/400 allows sockets, intersystem communications function (ICF), CPI
Communications (CPI-C), and CICS/400 applications to run over APPC, TCP/IP,
and Internetwork Packet eXchange (IPX). AnyNet/400 is based on the Multiprotocol
Transport Network (MPTN) architecture, and is designed to allow any application to
run over any networking protocol. Youcan use AnyNet/400 to:
vAccess APPC using TCP/IPif your applications were developed for system
network architecture (SNA) but you are using TCP/IP to connect the systems
vAccess APPC using IPX if your applications were developed for SNAbut you are
using IPX to connect the systems
vAccess sockets using SNA if your sockets applications were developed for
TCP/IP but you are using SNA to connect the systems
vAccess sockets using IPX if your sockets applications were developed for TCP/IP
but you are using IPX to connect the systems.
AnyNet/400 is shipped with the AS/400 base operating system, OS/400.
Chapter1. TCP/IP on AS/400 19