IBM SG24-4576-00 manual Packet Size, Packet Receive Buffers, Recommendation

5.3.2.2 Packet Size

Different network topologies will use different packet sizes. For example, a token-ring LAN adapter set to 16 Mbps can use packets of up to 4202 bytes. If the packet size is left at the network default value, which is 1514 bytes, this could unnecessarily slow down the LAN adapter performance. The reason for this is that it takes just as many instructions to process a small frame as it does a larger frame. Therefore, for a given amount of data to transfer, the larger frames will be transferred more quickly. You can adjust the packet size using set commands.

For NetWare 3.12 and 4.1, the syntax is:

SET MAXIMUM PHYSICAL RECEIVE PACKET SIZE = VALUE

Default = 1514

Range = 618 to 24682

Recommendation:

1.For token-ring 16 Mbps = 4202 packet size

2.For token-ring 4 Mbps = 2154 packet size

3.For Ethernet 10 Mbps = 1514 packet size

In the case of 4 Mbps token-ring adapters, a packet size of 4202 can be supported on some of the newer IBM LAN adapters.

Note

If you are in a multi-segment LAN or WAN environment, you must make sure that all inter-networking devices (bridges and routers for example) are capable of passing the packet size that you choose.

5.3.2.3 Packet Receive Buffers

Packet receive buffers hold communication packets that are waiting to be processed or transmitted. You can adjust the minimum and maximum number of buffers that NetWare generates by changing the following parameters:

1.MINIMUM PACKET RECEIVE BUFFERS (STARTUP.NCF)

2.MAXIMUM PACKET RECEIVE BUFFERS (STARTUP.NCF or AUTOEXEC.NCF)

The syntax is as follows:

SET MINIMUM PACKET RECEIVE BUFFERS=VALUE

SET MAXIMUM PACKET RECEIVE BUFFERS=VALUE

Minimum Packet Receive Buffers: NetWare 3.12

Default = 10

Range = 10 to 100

Recommendation: This value can vary depending on the number of LAN adapters and the number of users on the LAN. Allow at least 10 buffers for each LAN adapter card and one buffer per active LAN user. Active LAN users can be

Chapter 5. Performance Tuning 183