Troubleshooting Checkpoints

To isolate and resolve problems with source route bridging, complete the following steps:

Load BRGCON and check the value of the Number of Ports field displayed on the main window to verify that it matches the number of interfaces configured.

If the value of the Number of Ports field is incorrect, load NIASCFG and use the Boards option to add or configure network interface boards (parameter path: Configure NIAS > Protocols and Routing > Boards). Reinitialize the system and continue with Step 2 .

If the value of the Number of Ports field is correct, go to Step 3 .

Load BRGCON and check the value of the Number of Ports field.

If the value of the Number of Ports is still incorrect, load NIASCFG. Inspect the Boards option to make sure that the correct network boards and hardware parameters are selected. Verify that the source route bridge software is bound to the appropriate boards under Bindings. Reinitialize the system.

NOTE: The BRGCON Interfaces option gives information about all the boards, whether or not they are bound to the source route bridge. For information about any token ring port associated with the source route bridge software, look under the Ports option.

Load BRGCON and inspect the following parameters under the Ports option for token ring interfaces:

Hop Counts (Range: 1-13)

This field indicates the maximum number of hops (bridges) allowed for all routes or spanning tree explorer frames.

If this field is incorrect, load NIASCFG. Check the Protocols option for the source route bridge software (parameter path: Select Configure NIAS > Protocols and Routing > Protocols). Change the following parameters:

All Routes Explorer Frame Hop Count Limit (1-13)

Single Route Explorer Frame Hop Count Limit (1-13)

Local Ring (Range: 1-FFF)

This field identifies the ring (ring number and segment number are the same) that uniquely identifies the segment to which this port is connected.

All source route bridges on a given ring must assign the same value to the Ring Number option for that ring. If this field is incorrect, load NIASCFG. Check the bindings for the source route bridge software (parameter path: Select Configure NIAS > Protocols and Routing > Bindings). Change the Ring Number value.

Bridge Number (Range: 0-F)

This field identifies a bridge. When more than one bridge is used to span the same two segments, each bridge must have a unique number.

If this field is incorrect, load NIASCFG. Check the Protocols option for the source route bridge software and inspect the Bridge Number option of the source route bridge configuration. If the Bridge Number is incorrect, change it to reflect the correct value.

Target Ring (Range: 0-FFF)

This field displays a nonzero value only when the bridge is configured with a virtual ring. The Virtual Ring Number is required only when more than two interfaces are bound to the bridge.

Largest Frame (valid frame sizes are 512, 1500, 2052, 4472, 8144, 11407, and 17800)

This field indicates the maximum size of the frame's INFO field (Logical Link Control [LLC] and higher) that this port can send and receive. The value is the smallest number of the following values:

The value configured is the Largest Frame Size option in NIASCFG

The maximum receive buffer size of the server

The maximum packet size the driver can forward

If the value is larger than the smallest of these three parameters, load NIASCFG and check the bindings for the source route bridge software. Change the Largest Frame Size option in NIASCFG.

Spanning Tree Mode (valid options are Auto, Manual Blocking, Manual Forwarding, and No Bridging)

This field determines how this port responds when it is presented with a spanning tree explorer frame.

If this field is incorrect, load NIASCFG. Check the bindings for the source route bridge software and change the Spanning Tree Mode field.

Unless you are an expert user, keep the default mode of Auto.

Use NIASCFG to check the Protocols and Bindings options for the source route bridge software and inspect additional fields that cannot be viewed through BRGCON.

If any of the information displayed under these options is incorrect, load NIASCFG and select the Protocols or Bindings option (parameter path: Select Configure NIAS > Protocols and Routing > Protocols or Bindings). Change the following parameters, as needed:

Bridge Status (valid options are Enabled or Disabled)

You must enable the source route bridge software to configure the other bridging parameters.

Virtual Ring Number (Range: 0-FFF)

The Virtual Ring Number is required only when more than two interfaces are bound to the source route bridge.

Frame Type

This field identifies the frame type of the LAN board to which the source route bridge is bound. If you are not an expert user, use NIASCFG to bind the bridge to all the known frame types.

Path Cost Increment (Range: 0-65535)

This field specifies the path cost increment for the source route bridge. The lower the value, the more likely that the Spanning Tree Protocol will select the source route bridge as the root of the spanning tree. Only source route bridges determined to be in the spanning tree will forward all the single-route explorer frames.

Load BRGCON and inspect the Source Route Port Statistics option under Ports.

The various counters might identify some of the problems that are related to source route bridge configurations and source route bridge frame forwarding functions.

Specifically Routed Frames Received Counter

This field indicates the number of specifically routed frames that have been received by this port. If this value is zero, the wrong frame type might have been selected (or not all required frame types were selected). Load NIASCFG and check the frame type for the source route bridge software. If the frame type is incorrect, select the appropriate frame type.

All Routes Explorer Frames Received Counter

This field indicates the number of all-routes explorer frames that have been received by this port. If this value is zero, the wrong frame type might have been selected. Load NIASCFG and check the frame type for the source route bridge software. If the frame type is incorrect, select the appropriate frame type. This counter might also remain zero when no end stations are using all-routes explorer frames.

Spanning Tree Explorer Frames Received Counter

This field indicates the number of spanning tree explorer frames that have been received by this port from its segment. If this value is zero, the Spanning Tree Protocol for the source route bridge software might be disabled. Load NIASCFG and check whether the Spanning Tree Protocol is enabled for the source route bridge software.

Specifically Routed Frames Transmitted Counter

This field indicates the number of specifically routed frames that this port has transmitted on its segment.

If this value is zero, filters might be discarding all data or data using a certain frame type, or the receiving port might not be bound to the source route bridge.

All Routes Explorer Frames Transmitted Counter

This field indicates the number of all-routes explorer frames that this port has transmitted on its segment.

If this value is zero, filters might be discarding all data or data using a certain frame type, or the receiving port might not be bound to the source route bridge.

Spanning Tree Explorer Frames Transmitted Counter

This field indicates the number of spanning tree explorer frames that this port has transmitted on its segment. If this value is zero, the Spanning Tree Protocol for the source route bridge software might be disabled. Load NIASCFG and check whether the Spanning Tree Protocol is enabled for the source route bridge software.

Frames Discarded Due to an Invalid Adjacent Ring Value

This field indicates the number of frames that have been discarded by this port because the frame's routing information field contained an invalid adjacent segment value. A nonzero value usually indicates a configuration problem with the Ring Number NIASCFG option of this or another source route bridge on the ring.

Frames Discarded Due to a Duplicate Ring Identifier

This field indicates the number of frames that have been discarded by this port because the frame's routing information field contained a duplicate ring number.

A nonzero value usually indicates that more than one ring in the source route topology has been assigned the same ring number.

Frames Discarded Due to Too Many Hops

This field indicates the number of explorer frames that have been discarded by this port because the frame's routing information field has exceeded the maximum descriptor length.

If this counter is nonzero, the source route topology contains more sequential bridges than the maximum hop count supported by this bridge. This condition does not present a problem as long as no servers are separated from their clients by more than seven hops.

Check the following miscellaneous items in NIASCFG:

Verify that all source route bridges on a given token ring have been assigned the same Ring Number value for the interfaces to that ring.

Make sure that all token rings in a source route topology have been assigned a unique Ring Number value.

If you are employing two or more parallel bridges between the same two token rings, make sure that each parallel bridge has been assigned a unique Bridge Number value.

If a given bridge uses more than two interfaces (either token rings or WAN ports), you might need a Virtual Ring Number value. You receive a warning message when three or more interfaces are bound to the bridge and a virtual ring is required. When a virtual ring is required, make sure that the Virtual Ring Number value is also unique across the source route topology.

When configuring a bridged WAN link using the Virtual WAN Ring option (between the two bridges), make sure that the Ring Number value is the same on both ends.

When configuring a bridged WAN link without using the Virtual WAN Ring option (half-bridges), make sure that the Bridge Numbers values of both bridges are the same and that the Ring Numbers values are the remote target rings.

If you use parallel half-bridges, make sure that the WAN Link Identifier fields match.

Verify that the defined speeds of the token ring interface cards match the speed of the rings.