IBM SC41-5420-04 Tcp/Ip Configuration And Reference page 86

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72
OS/400 TCP/IP Configuration and Reference V5R1
v Checksum calculation of outgoing TCP and UPD datagrams (prior to V4R4)
v Checksum verification of incoming TCP and UPD datagrams (prior to V4R4)
v Outbound batching of TCP and UDP datagrams.
v Fragmentation of TCP and UDP datagrams into segments that match the MTU
size.
v Starting with V4R2, iSeries collects all TCP datagrams in one batch and UDP
datagrams in a second batch. Ports and IP addresses are ignored. Releases prior
to V4R2 batch together datagrams at the IOP when these conditions are true:
– The protocol (TCP or UDP) matches
– The source and destination ports match
– The source IP address and destination IP address match
– They arrive consecutively into the IOP
The IOP then passes the datagram batch to IP.
v Handling of IP and ICMP datagrams in error (unless IP NAT, which disables this
function, is active)
v Resolving physical addresses using ARP protocol
These functions are called TCP/IP-assist functions. Whether these functions are done
by the IOP or the System Licensed Internal Code (SLIC), depends on the IOP type,
the OS/400 release, and the TCP/IP configuration. For details about specific
functions, contact your local service representative. TCP/IP-assist functions are
available on these IOPs:
v #2617 Ethernet/IEEE 802.3 adapter/HP
v #2619 16/4 Mbps Token-Ring Network adapter/HP
v #2618 Fiber distributed data interface adapter (FDDI)
v #2665 Shielded distributed data interface adapter (SDDI)
v #2666 High-speed communication adapter that is running frame relay only
v #2668 iSeries wireless LAN adapter
Note: You can get the same function without using one of the above IOP adapters
(done instead at a higher level in the system (SLIC)). When you use the X.25
protocol, you do not gain the advantage of the TCP/IP-assist function.
The TCP/IP-assist functions are also available on the following LAN IOAs and ATM
IOAs:
v #2723 PCI Ethernet IOA
v #2724 PCI Token-Ring IOA
v #2838 PCI 100/10 Mbps Ethernet IOA
v #6149 16/4 Mbps Token-Ring IOA
v #2811 PCI 25 Mbps UTP ATM IOA
v #2812 PCI 45 Mbps Coax T3/DS3 ATM IOA
v #2813 PCI 155 Mbps MMF ATM IOA
v #2814 PCI 100 Mbps MMF ATM IOA
v #2815 PCI 155 Mbps UTP 0C3 ATM IOA
v #2816 PCI 155 Mbps MMF ATM IOA
v #2818 PCI 155 Mbps SMF 0C3 IOA
v #2819 PCI 34 Mbps Coax E3 ATM IOA