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This chapter describes how to configure Token Ring switching on the Catalyst 5000 family switch. The Token Ring modules have 16 shielded RJ-45 (copper) or Volition (fiber) ports for Token Ring connections. These ports allow full- or half-duplex connections to other switches, hubs, or end nodes.
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Note For complete information on installing Catalyst 5000 family Token Ring switching modules, refer to the Catalyst 5000 Family Module Installation Guide. |
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Note For complete syntax and usage information for the commands used in this chapter, refer to the Command Reference publication for your switch. |
This chapter consists of these sections:
These sections describe how Token Ring switching works:
The Catalyst 5000 family Token Ring modules provide these features:
In addition to the standard Management Information Base (MIB) objects supported by the Catalyst 5000 family switch, the Token Ring modules support these additional MIBs:
The proprietary MIBs supported are:
Most user-configurable variables are supported in either the standard MIBs or private MIBs:
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Note The Catalyst 5000 Family Token Ring module requires supervisor engine module software, Release 3.1 or later. Soft error monitoring and remove adapter support requires Token Ring software Release 3.3(1) or later and supervisor engine module software Release 5.1(1) or later. |
A source-route bridge makes all forwarding decisions based on data in the Routing Information Field (RIF). It does not learn or look up Media Access Control (MAC) addresses; SRB frames without a RIF are not forwarded.
Typically, clients or servers that support source routing send an explorer frame to determine the path to a given destination. There are two types of explorer frames: All-Routes Explorer and Spanning-Tree Explorer. All SRB bridges copy All-Routes Explorer frames and add their own routing information. For frames that are received from or sent to ports that are in the spanning-tree forwarding state, bridges copy Spanning-Tree Explorer frames and add their own routing information. Because All-Routes Explorer frames will traverse all paths between two devices, they are used in path determination. Spanning-Tree Explorer frames are used to send datagrams because the spanning tree ensures that only one copy of a Spanning-Tree Explorer frame is sent to each ring.
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Note The spanning tree used with source-routing is different from the IEEE spanning tree used in transparent bridges. The Catalyst 5000 family Token Ring modules support both types of spanning-tree algorithms. |
SRT bridging is an IEEE standard that combines source-route bridging and transparent bridging. An SRT bridge forwards frames that do not contain a RIF based on the destination MAC address. Frames that contain a RIF are forwarded based upon source routing. The SRT bridge only runs the IEEE Spanning-Tree Protocol. SRT does not support the IBM Spanning-Tree Protocol.
The Token Ring modules can forward broadcast, multicast, and unicast frames based on MAC addresses. If you have source-route bridges in your network, the Token Ring modules can forward frames based on the RIF. This dual frame-forwarding technology is called source-route switching.
In source-route switching, the switch learns and forwards frames based on source-route descriptors for stations that are one or more source-route bridge hops away. A route descriptor is a portion of a RIF that indicates a single hop. It is defined as a ring number and a bridge number. When a source-routed frame enters the switch, the switch learns the route descriptor for the hop closest to the switch. Frames received from other ports with the same next-hop route descriptor as their destination are forwarded to that port.
The key difference between SRB and source-route switching is that while a source-route switch looks at the RIF, it never updates the RIF. Therefore, all ports in a source-route switch group have the same ring number.
Source-route switching provides the following benefits:
To set the bridging mode of a Token Ring Concentrator Relay Function (TrCRF), perform this task in privileged mode:
| Task | Command |
|---|---|
Set the bridging mode. | set vlan vlan_num [mode {srt | srb}] |
The Token Ring modules support a new token-passing standard called Dedicated Token Ring (DTR). DTR provides the following functions:
DTR provides improved access to central resources such as network servers. The server can use the full 16 Mbps available for sending and receiving, which results in an aggregate bandwidth of 32 Mbps.
Table 40-1 shows the Token Ring default configuration.
| Feature | Default Value |
|---|---|
Port enable state | All ports are enabled |
Port name | None |
Port priority | Normal |
Port speed | Auto-detect |
Duplex mode | Autonegotiate half- or full-duplex mode |
Transmission threshold | 3 |
Minimum transmit setting | 4 |
VLAN | All ports assigned to default TrCRF |
Spanning-Tree Protocol | Enabled for all ports |
All-Routes Explorer reduction | Enabled |
Soft Error Monitoring | Disabled |
These sections describe how to configure Token Ring switching:
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Caution Changing certain configuration parameters of a connected port will cause the port to close and reopen. You will lose all address information and statistics for that port. |
To assign a name to a port on the Token Ring module, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | set port name mod_num/port_num name | |
Step 2 | Verify that the port name is configured. | show port [mod_num[/port_num]] |
This example shows how to set the name for a port and how to verify the name assignment:
Console> (enable) set port name 3/2 Print-1st Floor Port 3/2 name set. Console> (enable) show port 3/2 Port Name Status Vlan Level Duplex Speed Type ----- ------------------ ---------- ---------- ------ ------ ----- ------------ 3/2 Print-1st Floor inactive 1003 normal fdx 16 TokenRing Last-Time-Cleared -------------------------- Wed May 6 1998, 18:09:47 Console> (enable)
To address the needs of delay-sensitive data, each port on a Token Ring module has two data queues: high-priority and low-priority queues.
The queue is determined by the value of the priority field in the frame control (FC) byte of the frame. If the FC priority is above the user-defined priority level, the frame is put in the high-priority queue and is transmitted using the frame priority. If the FC priority is at or below the user-defined priority level, the frame is sent to the low-priority queue.
You can set two types of frame priorities for a port:
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Note The defaults for the priority queue are compatible with current source-route bridges and provide a high-priority queue for Token Ring multimedia traffic (priorities 5 and 6). |
To set the frame priority levels for a port, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Set the frame priority levels for a port. | set tokenring priority mod_num/port_num {threshold 0-7 | minxmit 0-6} |
Step 2 | Verify the priority configuration. | show tokenring [mod_num[/port_num]] |
This example shows how to set the Token Ring priority threshold to 6 on a port:
Console> (enable) set tokenring priority 3/2 threshold 6 Port 2 priority threshold set to 6. Console> (enable) show tokenring 3/2 Ports Crf/Brf Ring# Port-Mode Early-Token AC-bits ----- --------- ----- ------------- ----------- -------- 3/2 1003/1005 3276 fdx-cport enabled disabled Ports Prior-Thresh Min-Xmit MAC-Address ----- ------------ -------- ----------------- 3/2 6 5 00:40:0b:01:bc:65 Ports Cfg-Loss-Thresh Cfg-Loss-Intvl Cfg-Loss-Count Cfg-Loss-Reason ----- --------------- -------------- -------------- --------------- 3/2 50 20 0 none Console> (enable)
The Token Ring modules support 4- and 16-Mbps Token Ring transmission speeds. You can configure ports on the Token Ring modules to operate at one of these speeds or to automatically sense the speed of the ring to which it is connected (the default setting). However, with Token Ring technology, you cannot change the transmission speed without closing and reopening the port. These rules apply:
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Note If the ports on the Token Ring modules are configured to automatically sense the speed of the ring, the first port inserted on the ring does not set the speed, because it cannot detect the speed. |
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Note Closing and opening the port on an existing ring at a different transmission speed from which the ring is currently operating causes the port to issue a beacon on that ring. |
To set the transmission speed for a port on the Token Ring module, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Set the transmission speed for a Token Ring module port. | set port speed mod_num/port_num {4 | 16 | auto} |
Step 2 | Verify the port speed. | show port [mod_num[/port_num]] |
This example shows how to set the ring speed for a port and verify the configuration:
Console> (enable) set port speed 3/2 16 Port 3/2 speed set to 16Mbps. Console> (enable) show port 3/2 Port Name Status Vlan Level Duplex Speed Type ----- ------------------ ---------- ---------- ------ ------ ----- ------------ 3/2 Print-1st Floor inactive 1003 normal fdx 16 TokenRing Last-Time-Cleared -------------------------- Wed May 6 1998, 18:09:47 Console> (enable)
Each port on the Token Ring module can operate in one of these modes:
The default mode, auto, enables the port to detect the transmission mode it needs to use. However, you can configure the mode if necessary.
To set the transmission mode for a port, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Set the transmission mode for a port. | set tokenring portmode mod_num/port_num {auto | fdxcport | hdxcport | fdxstation | |
Step 2 | Verify the transmission mode setting. | show tokenring [mod_num[/port_num]] |
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Note The Ring in /Ring out (riro) parameter applies to the ports on a fiber Token Ring module only. |
This example shows how to set the transmission mode for a port and verify the configuration:
Console> (enable) set tokenring portmode 3/2 fdxcport Port 3/2 mode set to fdxcport Console> (enable) show tokenring 3/2 Ports Crf/Brf Ring# Port-Mode Early-Token AC-bits ----- --------- ----- ------------- ----------- -------- 3/2 1003/1005 3276 fdx-cport enabled disabled Ports Prior-Thresh Min-Xmit MAC-Address ----- ------------ -------- ----------------- 3/2 6 5 00:40:0b:01:bc:65 Ports Cfg-Loss-Thresh Cfg-Loss-Intvl Cfg-Loss-Count Cfg-Loss-Reason ----- --------------- -------------- -------------- --------------- 3/2 50 20 0 none
The interface ports on the Token Ring modules support early token release. Early token release allows a station to release a new token onto the ring immediately after transmitting, instead of waiting for the first frame to return. Early token release increases the total bandwidth on the ring. All ports, by default, are enabled to use early token release.
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Note Early token release is valid for 16-Mbps media only. If early token release is enabled and the media speed is 4 Mbps, the switch disables this feature. |
To enable the early token release feature on a Token Ring module port, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Enable the early token release feature on a Token Ring module port. | set tokenring etr mod_num/port_num enable |
Step 2 | Verify the early token release configuration. | show tokenring [mod_num[/port_num]] |
This example shows how to enable early token release and verify the configuration:
Console> (enable) set tokenring etr 3/2 enable Port 3/2 Early Token Release enabled. Console> (enable) show tokenring 3/2 Ports Crf/Brf Ring# Port-Mode Early-Token AC-bits ----- --------- ----- ------------- ----------- -------- 3/2 1003/1005 3276 fdx-cport enabled disabled Ports Prior-Thresh Min-Xmit MAC-Address ----- ------------ -------- ----------------- 3/2 6 5 00:40:0b:01:bc:65 Ports Cfg-Loss-Thresh Cfg-Loss-Intvl Cfg-Loss-Count Cfg-Loss-Reason ----- --------------- -------------- -------------- --------------- 3/2 50 20 0 none Console> (enable)
To disable the early token release feature on a Token Ring module port, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Disable early token release on a Token Ring module port. | set tokenring etr mod_num/port_num disable |
Step 2 | Verify the early token release configuration. | show tokenring [mod_num[/port_num]] |
Using the set tokenring actbits command, you can specify if and how the AC bits should be set on LLC frames. When local address learning is enabled on a Token Ring port, the default is disable. When local address learning is disabled on a Token Ring port, the default is always.
For information on setting AC bits and enabling and disabling local address learning, see the "Handling Frames Transmitted with Invalid Source MAC Addresses" section.
To configure how the AC bits will be set for a port, perform the following task in privileged mode:
| Task | Command |
|---|---|
Set AC bits on LLC frames. | set tokenring acbits mod_num/port_num {enable | disable | sronly | never | always} |
After entering the set tokenring acbits command, a display similar to the following appears:
Console> (enable) set tokenring acbits 3/2 always Warning: Disable Local learning: 3/2 Port 3/2 acbits always
Configuration loss occurs when a port completes a connection, allows data traffic to flow, and subsequently closes. The configuration loss threshold controls the number of configuration losses that can occur within a specified time. When the threshold is exceeded, the port is disabled and you must enable it by entering the set port enable command or an SNMP manager. The valid range for the configuration loss threshold is 1 through 100. The default is 8.
To set and verify the configuration loss threshold for a port, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Set the configuration loss threshold for a port. | set tokenring configloss mod_num/port_num {threshold <1..100> | interval <1..9999>} |
Step 2 | Verify the configuration loss threshold setting. | show tokenring [mod_num[/port_num]] |
This example shows how to set the configuration loss threshold for a port and verify the configuration:
Console> (enable) set tokenring configloss 3/2 threshold 50 Port 3/2 configloss threshold set to 50. Console> (enable) set tokenring configloss 3/2 interval 20 Port 3/2 configloss interval set to 20. Console> (enable) show tokenring 3/2 Ports Crf/Brf Ring# Port-Mode Early-Token AC-bits ----- --------- ----- ------------- ----------- -------- 3/2 1003/1005 3276 fdx-cport enabled enabled Ports Prior-Thresh Min-Xmit MAC-Address ----- ------------ -------- ----------------- 3/2 6 5 00:40:0b:01:bc:65 Ports Cfg-Loss-Thresh Cfg-Loss-Intvl Cfg-Loss-Count Cfg-Loss-Reason ----- --------------- -------------- -------------- --------------- 3/2 50 20 0 none Console> (enable)
For parallel SRB or SRT backbones, All-Routes Explorer reduction ensures that the number of All-Routes Explorer frames generated by the switch does not overwhelm the network.
In accordance with the IEEE 802.1d SRT standard, the Token Ring module discards any All-Routes Explorer frames that have already been on a ring attached to the switch. This ensures that only one All-Routes Explorer frame is received on each ring within each VLAN (Token Ring Bridge Relay Function [TrBRF] and Token Ring Concentrator Relay Function [TrCRF]). The number of frames is equal to the number of external parallel paths between the rings. If a port on the switch fails or is disabled, the switch no longer checks for this ring number in the RIF. This bypass allows frames to travel on alternate paths.
By default, All-Routes Explorer reduction is enabled.
To enable All-Routes Explorer reduction, perform this task in privileged mode:
| Task | Command |
|---|---|
Enable All-Routes Explorer reduction. | set tokenring reduction enable |
To disable All-Routes Explorer reduction, perform this task in privileged mode:
| Task | Command |
|---|---|
Disable All-Routes Explorer reduction. | set tokenring reduction disable |
The Catalyst 5000 Family Token Ring module software Release 3.3(1) and later performs error detection and isolation by monitoring the Report Soft Error MAC frames generated by stations on each port. Soft errors occur during normal ring operation and do not typically disrupt traffic on the ring. However, soft errors can occur at a rate that could potentially degrade the performance of
the ring.
Using the set station softerror command, you can enable or disable soft error monitoring on a Token Ring port and you can configure soft error thresholds and sampling intervals for a port. During the interval you define, the Catalyst 5000 Family Token Ring module monitors the stations on the port and, if the threshold is exceeded, can be configured to generate a trap indicating the port number and station on which the threshold was exceeded. If necessary, you can issue a Remove Ring Station MAC frame to remove the station from the ring.
The Catalyst 5000 Family Token Ring module performs the following tasks:
To enable or disable soft error monitoring on a Token Ring port, perform the following task in privileged mode:
| Task | Command |
|---|---|
Enable soft error monitoring on a port. | set station softerror mod_num | mod_num/port_num disable | enable |
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Note To enable soft error monitoring on all the ports of the Token Ring module, use the set station softerror command and specify the module number of the Token Ring module. |
After enabling soft error monitoring on a port using the set station softerror command, you see a display similar to the following:
Console> (enable) set station softerror 3/10 enable Port 3/10 soft error monitoring enabled. Console> (enable)
A soft error monitoring error threshold is the number of soft errors reported from a station connected to a port that if exceeded causes a soft error exceeded trap to be issued. To configure a soft error monitoring threshold and to define a sampling interval (the period, in seconds, during which the number of soft errors is monitored for each station connected to this port) perform the following task in privileged mode:
| Task | Command |
|---|---|
Configure soft error monitoring thresholds and sampling intervals on a port. | set station softerror mod_num[/port_num] threshold threshold_num interval int_num |
The possible values for the error threshold are 1 to 255. The default is 100. The possible values for the sampling interval are 0 to 65534. The default is 60. Setting the interval to zero disables the soft error exceeded traps. Without these traps, soft errors can still be monitored through the console.
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Note To set the error threshold and sampling interval for all the ports of the Token Ring module, enter the set station softerror command and specify the module number of the Token Ring module. |
The following example shows how to configuring the error threshold and sampling interval using the set station softerror command:
Console> (enable) set station softerror 3/10 threshold 100 interval 200 Port 3/10 station soft error threshold set to 100, interval set to 200 Console> (enable)
To verify your soft error monitoring configuration on a port, perform the following task in privilege mode:
| Task | Command |
|---|---|
Display the soft error monitoring configuration on a port. | show station softerror config mod_num[/port_num] |
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Note To view the soft error monitoring configuration for all the ports of the Token Ring module, enter the show station softerror config command and specify the module number of the Token Ring module. |
The following example shows how to verify the configuration on a port:
Console> (enable) show station softerror config 3/10 Ports Threshold Interval Status ----- --------- -------- -------- 3/10 100 200 enabled Console> (enable)
If a station is exceeding soft error thresholds, you can issue a Remove Ring Station MAC frame to remove the station from the ring. When entering the clear station command, enter the MAC address in non-canonical format (00:11:22:33:44:55).
To remove the station from the ring, perform this task in privileged mode:
| Task | Command |
|---|---|
Clear a station from a ring. | clear station mod_num/port_num mac_addr |
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Caution Entering the clear station command and specifying the MAC address or ID of a station issues a Remove Station MAC frame to that station and removes the station from the ring. Use this procedure with extreme caution. |
In some rare circumstances, certain devices (such as a faulty protocol analyzer) might transmit a frame that contains the source MAC address of another device. Because MAC addresses are used by the switch to determine where to forward a frame, an invalid frame (one that contains the source MAC address of another device) can cause the valid frames to be forwarded to the wrong port. If this situation occurs, communication to the device to which the MAC address actually belongs can be disrupted for as long as the invalid address entry is in the Token Ring port address table.
If you are experiencing network communication problems due to a device erroneously sending frames with the source MAC address of another device, you can either choose to rapidly age the entries out of the Token Ring module port address tables using the set tokenring portaging command or you can ensure that the Token Ring module port address tables do not contain erroneous entries by disabling address learning entirely on the Token Ring module using the set tokenring locallearning command.
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Caution We recommend that you use the set tokenring portaging and set tokenring locallearning commands only in those rare circumstances in which network communications are disrupted because of invalid frames. |
When in a network environment in which a device is sending invalid frames, you can ensure that the Token Ring module port address tables contain correct MAC address entries by rapidly aging out the erroneous entries using the set tokenring portaging command. Rapidly aging out the Token Ring module port address table ensures that the Token Ring module port address tables do not contain invalid entries that might affect the Catalyst 5000 family switch and network communication.
The aging limit you define determines when inactive MAC addresses are removed from a port address table. The aging limit is the time (in seconds) a MAC address remains in the port's address table. Possible values are 0 and 5 through 65535 seconds. The default is 0. Zero indicates the Token Ring module port address table entries are aged out using the CAM aging time for the corresponding VLAN that has been configured using the set cam agingtime command. For more information about the set cam agingtime command, see the Command Reference for your switch.
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Note To use the fast-port aging feature effectively, we recommend that you configure an aging limit of 10. |
To define the address aging limits for a Token Ring port, perform the following task in privileged mode:
| Task | Command |
|---|---|
Define the address aging limits for a port. | set tokenring portaging mod_num/port_num agingtime |
This example shows how to define the address aging limit for a Token Ring port:
Console> (enable) set tokenring portaging 3/2 10 Agingtime set to 10 sec for port 3/2 Console> (enable)
The set tokenring locallearning command allows you to enable or disable local MAC address learning on a Token Ring port. The default is for local address learning to be enabled.
When local address learning is enabled, the value of the address recognized (A) bit and the frame copied (C) bit in LLC frames is set by the ports on the Token Ring module based on whether the frame was actually forwarded. However, when local address learning is disabled, the AC bits cannot be set by the ports on the Token Ring module based on whether the frame was forwarded because all frames are forwarded to the Catalyst 5000 Family switching backplane.
When local address learning is disabled on a Token Ring port, the AC bits must be set based on the type of frame that has been received. When you disable local address learning on a Token Ring port, the default is for the AC bits to always be set on LLC frames. You can configure how the AC bits are to be set using the set tokenring acbits command. For more information on configuring for the setting of AC bits on frames, see the "Setting Address-Recognized and Frame-Copied Bits" section.
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Note When local address learning is disabled on a port, the port aging limits that are configured using the set tokenring portaging command are not used. |
To enable or disable local address learning, perform the following task in privileged mode:
| Task | Command |
|---|---|
Enable or disable local address learing on a port. | set tokenring locallearning mod_num/port_num enable | disable |
This example shows how to disable local address learning using the set tokenring locallearning command:
Console> (enable) set tokenring locallearning 3/2 disable Warning: Resetting acbit value to ALWAYS: 3/2 Local learning disabled for port 3/2 Console> (enable)
Posted: Wed Mar 22 12:38:48 PST 2000
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