System information

42
AS/400 IBM Network Station: Techniques for Deployment in a WAN
Some customers who have Series 1000s have experienced performance
problems. The Series 1000 supports both full duplex and half duplex. In
general, the performance problem is caused by a configuration error. As a
result, the Series 1000 tries to operate in full duplex mode, but a router or
something else in the network supports only half duplex. The Series 1000
almost continuously runs into collisions on the Ethernet, which results in
extremely slow performance.
Some customers, who have Token-Ring network switches that pass 4K
frames, have experienced difficulties. These customers set their LAN frame
size or MTU to a value greater than 8K. In general, these customers used
NVRAM, with a default 1024 TFTP block size. Initialization works fine until
login, when RFS takes over and uses 8K frames. The 8K frames do not pass
through a 4K switch. Some solutions to this problem may be to configure the
switch to allow 8K frames, replace the switch with a router, or configure the
AS/400 LAN frame size/MTU to 4K (twinax is fixed at 4K).
If the network has no Domain Name Server (DNS), performance can be very
slow, since DNS time-outs in the region of 30 seconds occur frequently.
AS/400 V4R2 contains DNS support. If a customer does not wish to use a
DNS, for Release 3, good performance is still possible by performing the
following steps:
1. Enter
CFGTCP. Select option 12 ( Change TCP/IP domain information ). Set
Search priority to
*LOCAL
.
2. Enter
CFGTCP. Select option 10 ( Work with TCP/IP host table entries ). Add
the IP address and host name for the AS/400 system and each Network
Station.
3. Using Network Station Manager, select
Hardware
—>
Workstations
—>
Domain Name Server
. Set
Update Network Station Manager DNS file.
The initialization options described in this redbook is adequate for most
customer environments. There are other variations that can occur. For
example, if the customer chooses BOOTP and successfully loads the kernel,
but, for some reason, RFS is not working properly, initialization times out on
RFS and switches back to TFTP. Variations, such as these are not described
in this document. The BOOTP boot sequence is described in greater detail in
the following section.
2.5.1.3 BOOTP Initialization
There are four steps in the BOOTP initialization process. To get a total
initialization time, you need to add together the times from each.
1. Hardware test