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Windows 95, Windows 98, or Windows NT systems deployed with Microsoft's NWLink do not support large SPX network packets. This underlying protocol issue can cause problems on Token-Ring and FDDI, or in some cases, mixed LAN/WAN topology networks with IPX/SPX, generating the following Notes/Domino errors:

Client or Server Error Messages

• Server Not Responding
• Network Operation Did Not Complete in a Reasonable Amount of Time
• Remote System is No Longer Responding

• Mail Router spawning multiple sessions to other server.
• Replication failures and spawning multiple sessions to other server.
• "Security context error" when using passthru server services.

1. Use the Microsoft-supplied client with a NIC driver that can constrain the Frame size.

2. Use the Novell Client services with an ODI NIC driver that can set the Link Support Layer maximum buffer size.

Depending on the NIC vendor's driver, you must either alter the interface properties or edit the Registry to adjust the frame size. Review the documentation that came with your adapter, or discuss your requirements with the interface vendor's support staff. Use the table below to determine the frame sizes setting.

Novell stack

The Novell client services offer a way to prevent the creation of SPX packets that are too large for the other system to accept by using the "Link Support Layer Max Buffer Size" setting to control the transport buffer size. You also need to use an ODI-based adapter driver for the LSL buffer setting to work. Review the documentation that came with your adapter, or discuss your requirements with the interface vendor's support staff. Use the table below to determine the needed LSL buffer setting to control the Packet size setting.

Topology/Frame type	Frame size	IPX packet size	SPX data size	LSL buffer size	Comments
Ethernet/DIX or RAW	1518	1500	1458	N/A	Entry provided for reference only
Ethernet/802.2 LLC	1518	1496	1454	N/A	Entry provided for reference only
Token-Ring/802.2 LLC	1522	1500	1458	1500	Optimized for SPX crossing Eth with DIX or RAW to TR with Bridges or Routers
Token-Ring/802.2 LLC	1518	1496	1454	1496	Optimized for SPX crossing Eth with LLC to TR with Bridges or Routers
Token-Ring/802.2 LLC	2048	2026	1984	2026	Required for older 4Mb adapters & networks using them.
Token-Ring/802.2 LLC	4096	4074	4032	4074	Optimized for performance
Token-Ring/802.2 LLC	4202	4180	4138	4180	Novell default frame size
Token-Ring/802.2 LLC	4500	4478	4436	4478
FDDI/802.2 LLC	1538	1500	1458	1500	Optimized for SPX crossing Eth with DIX or RAW to FDDI with Bridges or Routers
FDDI/802.2 LLC	1534	1496	1454	1496	Optimized for SPX crossing Eth with LLC to FDDI with Bridges or Routers
FDDI/802.2 LLC	4112	4074	4032	4074	Optimized for SPX crossing TR using 4096 fs to FDDI with Bridges or Routers
FDDI/802.2 LLC	4218	4180	4138	4180	Optimized for SPX crossing TR using 4202 fs to FDDI with Bridges or Routers
FDDI/802.2 LLC	4516	4478	4436	4478	Optimized for SPX crossing TR using 4500 fs to FDDI with Bridges or Routers
FDDI/802.2 LLC	4096	4058	4016	4058	Optimized for performance
FDDI/802.2 LLC	4202	4164	4122	4164	Novell default frame size
FDDI/802.2 LLC	4500	4462	4420	4462

Note: Token-Ring allows larger frame/packet sizes than those listed here. In most cases, these are the values to use in your network; if you require other values, use the formulas given below.

Note: IPX using LLC/SNAP framing is not recommended and is not included in these tables.

Note: Windows NT systems using SPX II negotiate to the common packet size between the systems as needed.

The following formulas are used to derive the values in the table shown above:

Frame/IPX packet

Ethernet with DIX Frame size - MAC headers (18) = IPX packet size
Ethernet with LLC Frame size - MAC headers (18) - LLC headers (4) = IPX packet size
Token-Ring Frame size - MAC headers (18) - LLC headers (4) = IPX packet size
FDDI Frame size - MAC headers {ANSI standard} (34) - LLC headers (4) = IPX packet size

IPX packet to SPX data size (Notes RPC data stream)

IPX packet - IPX headers (30) - SPX headers (12) = SPX data size

Note: All measurements are in octets. Bytes is quite often used as the term but technically it is not the same.

During the workstation's (IPX client) attachment process, it accesses the NetWare server to acquire additional setting information, which includes the maximum frame size the NetWare server accepts. By default, the maximum frame size is set to 4202. With Ethernet networks, the topology's limitation of 1518 takes precedent, but with Token-Ring or FDDI networks, or mixed topology networks, this value can create problems with SPX communication.

Within a flat network, make sure the settings of the Notes and Domino server systems are set for the NetWare default settings as needed. If you have a Switched, Bridged, or Routed network with either Token-Ring or FDDI, it is recommended that you alter the NetWare servers setting "Set Maximum Physical Receive Packet Size" to 4096 to better match the memory buffers of the switches, bridges, and routers. With a mixed topology network, you may need to use one of the optimized choices listed in the table above. The guidelines you should use are as follows:

• Transparent Bridge or Straight-Routed networks with Token-Ring or FDDI: Use the entries in the table as needed.
• Token-Ring Source Route Bridged networks: An additional 30 bytes must be subtracted to account for the RIF field in the IPX packet, SPX packet, and LSL buffer settings. This applies only to Token-Ring or FDDI network values and ones that are not optimized for SPX conversion with Ethernet.
• Translational Bridge between Token-Ring or FDDI and Ethernet networks: Use the optimized listings in the table as required.
• Transparent or Source Route Bridges between FDDI and Token-Ring: Use the optimized listings in the table as required.

• Routing between Token-Ring or FDDI to Ethernet networks or between Token-Ring to FDDI networks: Use the optimized listings the table as required.

If you are using the NetWare server as a Router with Token-Ring, it is recommended that the NetWare server's STARTUP.NCF file contain the following line:

Set Maximum Physical Receive Packet Size = 4096

Follow with any needed alterations to the Domino server and Notes client systems. This ensures all the end nodes that are accessing this NetWare server are using the 4096 frame limit.

Note: Your network may require different values if there are network segments set up with a lower frame or packet size. Consult your network administrator to discuss any possible conflicts, and use the largest value your network can support.</TD></TABLE>