Table Of Contents

Configuring Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet Switching

Understanding How Ethernet Works

Switching Frames Between Segments

Building the Address Table

Understanding Port Negotiation

Default Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet Configuration

Setting the Port Configuration

Configuring Supervisor Engine 720 Ports

Setting the Port Name

Setting the Port Speed

Setting the Port Duplex Mode

Enabling or Disabling Auto-MDI/MDIX

Configuring IEEE 802.3x Flow Control

Enabling and Disabling Port Negotiation

Changing the Default Port Enable State

Setting the Port Debounce Timer

Modifying the Port Debounce Timer Setting

Configuring a Timeout Period for Ports in errdisable State

Configuring Automatic Module Shutdown

Configuring Port Error Detection

Configuring Redundant Flex Links

Redundant Flex Link Configuration Guidelines and Restrictions

Specifying the Active and Backup Ports for the Flex Links

Displaying the Port Configuration of the Flex Links

Clearing the Port Configuration of the Flex Links

Configuring Jumbo Frames

Configuring Jumbo Frames on the Supervisor Engine

Configuring Jumbo Frames on the MSFC2

Checking Connectivity

Configuring Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet Switching

---

This chapter describes how to use the command-line interface (CLI) to configure Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet switching on the Catalyst 6500 series switches. The configuration tasks in this chapter apply to Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet switching modules, as well as to the uplink ports on the supervisor engine.

---

Note For complete syntax and usage information for the commands that are used in this chapter, refer to the Catalyst 6500 Series Switch Command Reference publication.

---

This chapter consists of these sections:

•Understanding How Ethernet Works

•Default Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet Configuration

•Setting the Port Configuration

Understanding How Ethernet Works

Catalyst 6500 series switches support simultaneous, parallel connections between Ethernet segments. Switched connections between Ethernet segments last only for the duration of the packet. New connections can be made between different segments for the next packet.

Catalyst 6500 series switches solve congestion problems that are caused by high-bandwidth devices and a large number of users by assigning each device (for example, a server) to its own 10-, 100-, 1000-, or 10000-Mbps segment. Because each Ethernet port on the switch represents a separate Ethernet segment, the servers that are in a properly configured switched environment achieve full access to the bandwidth.

Because collisions are a major bottleneck in the Ethernet networks, an effective solution is full-duplex communication, which is an option for any 10- or 100-Mbps port on a Catalyst 6500 series switch (the Gigabit Ethernet and 10-Gigabit Ethernet ports are always full duplex). Typically, Ethernet operates in half-duplex mode, which means that stations can either receive or transmit. In full-duplex mode, two stations can transmit and receive at the same time. When packets can flow in both directions simultaneously, effective Ethernet bandwidth doubles to 20 Mbps for 10-Mbps ports and to 200 Mbps for Fast Ethernet ports. The Gigabit Ethernet and 10-Gigabit Ethernet ports on the Catalyst 6500 series switches are full duplex only (2-Gbps and 20-Gbps effective bandwidth, respectively).

These sections describe Ethernet:

•Switching Frames Between Segments

•Building the Address Table

•Understanding Port Negotiation

Switching Frames Between Segments

Each Ethernet port on a Catalyst 6500 series switch can connect to a single workstation or server or to a hub through which workstations or servers connect to the network.

Ports on a typical Ethernet hub all connect to a common backplane within the hub, and the bandwidth of the network is shared by all devices that are attached to the hub. If two stations establish a session that uses a significant level of bandwidth, the network performance of all other stations that are attached to the hub is degraded.

To reduce degradation, the switch treats each port as an individual segment. When the stations on different ports need to communicate, the switch forwards the frames from one port to the other port at wire speed to ensure that each session receives full bandwidth.

To switch frames between ports efficiently, the switch maintains an address table. When a frame enters the switch, it associates the MAC address of the sending station with the port on which it was received.

Building the Address Table

Catalyst 6500 series switches build the address table by using the source address of the received frames. When the switch receives a frame for a destination address that is not listed in its address table, it floods the frame to all ports of the same VLAN except for the port that received the frame. When the destination station replies, the switch adds its relevant source address and port ID to the address table. The switch then forwards subsequent frames to a single port without flooding to all ports.

The address table can store at least 32,000 address entries without flooding any entries. The switch uses an aging mechanism, which is defined by a configurable aging timer, so if an address remains inactive for a specified number of seconds, it is removed from the address table.

Understanding Port Negotiation

---

Note The set port negotiation command is supported on Gigabit Ethernet ports only; it is not supported on the WS-X6316-GE-TX and WS-X6516-GE-TX modules. If a port does not support this command, this message appears: "Feature not supported on Port N/N," where N/N is the module and the port number.

---

---

Note You cannot configure port negotiation on 1000BASE-TX (copper) Gigabit Ethernet ports in this release. If you insert a 1000BASE-TX GBIC in the port that was previously configured as negotiation disabled, the negotiation-disabled setting is ignored and the port operates in negotiation-enabled mode.

---

---

Note Port negotiation does not involve negotiating port speed. You cannot disable port negotiation with the set port speed command.

---

Port negotiation exchanges flow-control parameters, remote fault information, and duplex information. Configure port negotiation with the set port negotiation command. Port negotiation is enabled by default.

---

Note When you enable port negotiation on the 16-port 10/100/1000BASE-T Ethernet modules, the system autonegotiates flow control only.

---

The ports on both ends of a link must have the same setting. The link will not come up if the ports at each end of the link are set inconsistently (port negotiation is enabled on one port and is disabled on the other port).

Table 4-1 shows the four possible port negotiation configurations and the resulting link status for each configuration.

Table 4-1 Port Negotiation Configuration and Possible Link Status 

Port Negotiation State		Link Status
Near End1	Far End2	Near End	Far End
Off	Off	Up	Up
On	On	Up	Up
Off	On	Up	Down
On	Off	Down	Up

1 Near End refers to the local port. 2 Far End refers to the port at the other end of the link.

Default Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet Configuration

Table 4-2 shows the Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet default configuration.

Table 4-2 Ethernet Default Configuration 

Feature	Default Value
Port enable state	All ports are enabled
Port name	None
Duplex mode	•Half duplex for 10-Mbps Ethernet ports •Autonegotiate speed and duplex for 10/100-Mbps Fast Ethernet ports •Autonegotiate duplex for 100-Mbps Fast Ethernet ports •Full duplex for 1000-Mbps Gigabit Ethernet ports •Full duplex for 10000-Mbps Gigabit Ethernet ports
Flow control (10-Gigabit Ethernet)	Flow control set to on for receive (Rx) and off for transmit (Tx)1
Flow control (Gigabit Ethernet)	Flow control set to off for receive (Rx) and desired for transmit (Tx)
Flow control (other Ethernet)	Flow control set to off for receive (Rx); transmit (Tx) not supported
Spanning Tree Protocol (STP)	Enabled for VLAN 1
Native VLAN	VLAN 1
Port VLAN cost	•100 for 10-Mbps Ethernet ports •19 for 10/100-Mbps Fast Ethernet ports •19 for 100-Mbps Fast Ethernet ports •4 for 1000-Mbps Gigabit Ethernet ports •1 for 10000-Mbps Gigabit Ethernet ports
EtherChannel	Disabled on all Ethernet ports
Jumbo frames	Disabled on all Ethernet ports

1 On WS-X6502-10-Gigabit Ethernet ports, flow control on the receive side is always on and cannot be set to off. On WS-X6704, WS-X6708-10-Gigabit Ethernet ports and Supervisor Engine 720-10 Gigabit Ethernet uplink ports flowcontrol for both send and receive side can be set to off.

Setting the Port Configuration

These sections describe how to configure Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet switching on the Catalyst 6500 series switches:

•Configuring Supervisor Engine 720 Ports

•Setting the Port Name

•Setting the Port Speed

•Setting the Port Duplex Mode

•Enabling or Disabling Auto-MDI/MDIX

•Configuring IEEE 802.3x Flow Control

•Enabling and Disabling Port Negotiation

•Changing the Default Port Enable State

•Setting the Port Debounce Timer

•Modifying the Port Debounce Timer Setting

•Configuring a Timeout Period for Ports in errdisable State

•Configuring Automatic Module Shutdown

•Configuring Port Error Detection

•Configuring Redundant Flex Links

•Configuring Jumbo Frames

•Checking Connectivity

Configuring Supervisor Engine 720 Ports

Supervisor Engine 720, port 1 has a small form-factor pluggable (SFP) connector and no unique configuration options.

---

Note Cisco WS-X6408A-GBIC, which is an 8-port Gigabit Ethernet interface module for the Catalyst 6500 Series switches, is supported on Supervisor Engine 720.

---

Supervisor Engine 720, port 2 has an RJ-45 connector and an SFP connector (default). To use the RJ-45 connector, you must change the configuration.

To configure port 2 on Supervisor Engine 720, perform this task in privileged mode:

Task	Command
Configure port 2 on Supervisor Engine 720.	set port media-type mod/port {rj45 | sfp}

This example shows how to configure port 2 on Supervisor Engine 720 to use the RJ-45 connector:

Console> (enable) set port media-type 5/2 rj45

Port 5/2 media type set to RJ-45.

Console> (enable)

Setting the Port Name

You can set the port names on Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet switching modules to facilitate switch administration.

To set the port name, perform this task in privileged mode:

	Task	Command
Step 1	Set a port name.	set port name mod/port [name_string]
Step 2	Verify that the port name is configured.	show port [mod[/port]]

This example shows how to set the name for ports 1/1 and 1/2 and verify that the port names are configured correctly:

Console> (enable) set port name 1/1 Router Connection

Port 1/1 name set.

Console> (enable) set port name 1/2 Server Link

Port 1/2 name set.

Console> (enable) show port 1

Port  Name               Status     Vlan         Duplex Speed Type

----- ------------------ ---------- ----------   ------ ----- ------------

 1/1  Router Connection  connected  trunk          full  1000 1000BaseSX

 1/2  Server Link        connected  trunk          full  1000 1000BaseSX

.

.

.

Last-Time-Cleared

--------------------------

Wed Jun 16 1999, 16:25:57

Console> (enable)

Setting the Port Speed

You can configure the port speed on 10/100-Mbps Ethernet switching modules. Use the auto keyword to autonegotiate the port's speed and duplex mode with the neighboring port.

---

Note If the port speed is set to auto on a 10/100-Mbps Ethernet port, both speed and duplex are autonegotiated.

---

Use the auto-10-100 keyword on ports that support speeds of 10/100/1000 Mbps. Using the auto-10-100 keyword makes the port behave the same as a 10/100-Mbps port that has the speed set to auto. The speed and duplex are negotiated (the 1000-Mbps speed does not take part in the negotiation).

To set the port speed of an Ethernet port, perform this task in privileged mode:

	Task	Command
Step 1	Set the port speed of an Ethernet port.	set port speed mod/port {10 | 100 | 1000 | auto | auto-10-100}
Step 2	Verify that the speed of the port is configured correctly.	show port [mod[/port]]

This example shows how to set the port speed to 100 Mbps on port 2/2:

Console> (enable) set port speed 2/2 100

Port 2/2 speed set to 100 Mbps.

Console> (enable)

This example shows how to make port 2/1 autonegotiate speed and duplex with the neighboring port:

Console> (enable) set port speed 2/1 auto

Port 2/1 speed set to auto-sensing mode.

Console> (enable)

Setting the Port Duplex Mode

You can set the port duplex mode to full or half duplex for Ethernet and Fast Ethernet ports.

---

Note Gigabit Ethernet and 10-Gigabit Ethernet are full duplex only. You cannot change the duplex mode on Gigabit Ethernet and 10-Gigabit Ethernet ports.

---

---

Note If the port speed is set to auto on a 10/100-Mbps Ethernet port, both speed and duplex are autonegotiated. You cannot change the duplex mode of autonegotiation ports.

---

To set the duplex mode of a port, perform this task in privileged mode:

	Task	Command
Step 1	Set the duplex mode of a port.	set port duplex mod/port {full | half}
Step 2	Verify that the duplex mode of the port is configured correctly.	show port [mod[/port]]

This example shows how to set the duplex mode to half duplex on port 2/1:

Console> (enable) set port duplex 2/1 half

Port 2/1 set to half-duplex.

Console> (enable)

Enabling or Disabling Auto-MDI/MDIX

With auto-MDI/MDIX you can use either a straight or crossover cable, and the module will automatically detect and adjust for the cable type. Auto-MDI/MDIX works with the speed set to auto/1000 Mbps but not with the speed set to 10 Mbps or 100 Mbps. The link will come up with either a straight or crossover cable if the speed is set to auto/1000 using the set port speed mod/port auto command or the set port speed mod/port 1000 command. The link comes up even if the speed is autonegotiated at 10 Mbps or 100 Mbps in auto mode. However, if you enter the set port speed mod/port 10 command or the set port speed mod/port 100 command, the link fails to come up if the wrong cable is used.

Auto-MDI/MDIX has always been enabled on the following modules:

•WS-X6548-RJ-45, WS-X6548-RJ-21, WS-X6148-GE-TX, WS-X6548-GE-TX

Auto-MDI/MDIX works in 10-, 100-, and 1000-Mbps modes with autonegotiated and fixed speeds.

•WS-X6516-GE-TX

Auto-MDI/MDIX works with the speed set to auto/1000 Mbps but not with the speed set to 10 Mbps or 100 Mbps.

•WS-X6316-GE-TX

With software release 8.2(1) and later releases, auto-MDIX is also enabled on the following modules:

•WS-X6748-GE-TX, Supervisor Engine 720 port 2 (RJ-45)

Auto-MDI/MDIX works with the speed set to auto/1000 but not with the speed set to 10 Mbps or 100 Mbps

•WS-X6148X2-RJ-45, WS-X6148X2-45AF

Auto-MDI/MDIX works with the speed set to auto but not with the speed set to 10 Mbps or 100 Mbps.

---

Note Auto-MDI/MDIX is not supported on any other 10/100-Mbps Ethernet modules or GBIC, SFP, and XENPAK ports.

---

With software release 8.3(1) and later releases, the set port auto-mdix mod/port {enable | disable} command is introduced to disable auto-MDI/MDIX on all the modules that currently have this feature enabled by default. Use the show port auto-mdix [mod[/port]] command to display auto-MDI/MDIX settings.

Configuring IEEE 802.3x Flow Control

Gigabit Ethernet and 10-Gigabit Ethernet ports on the Catalyst 6500 series switches use flow control to inhibit the transmission of packets to the port for a period of time; other Ethernet ports use flow control to respond to flow-control requests.

If a Gigabit Ethernet or a 10-Gigabit Ethernet port receive buffer becomes full, the port transmits a "pause" packet that tells remote ports to delay sending more packets for a specified period of time. All Ethernet ports (10000 Mbps, 1000 Mbps, 100 Mbps, and 10 Mbps) can receive and act upon "pause" packets from other devices.

Enter the set port flow control command to configure flow control on ports. Table 4-3 lists the set port flowcontrol command keywords and describes their functions.

Table 4-3 Ethernet-Flow Control Keyword Functions 

Keywords	Function
receive on1	The port uses flow control dictated by the neighboring port.
receive desired	The port uses flow control if the neighboring port uses it and does not use flow control if the neighboring port does not use it.
receive off	The port does not use flow control, regardless of whether flow control is requested by the neighboring port.
send on2	The port sends flow-control frames to the neighboring port.
send desired2	The port sends flow-control frames to the port if the neighboring port asks to use flow control.
send off2	The port does not send flow-control frames to the neighboring port.

1 On WS-X6502-10-Gigabit Ethernet ports, flow control on the receive side is always on and cannot be set to off. On WS-X6704, WS-X6708-10-Gigabit Ethernet ports and Supervisor Engine 720-10 Gigabit Ethernet uplink ports flowcontrol for both send and receive side can be set to off. 2 Supported only on Gigabit Ethernet and 10-Gigabit Ethernet ports.

To configure flow control, perform this task in privileged mode:

	Task	Command
Step 1	Set the flow-control parameters.	set port flowcontrol mod/port {receive | send} {off | on | desired}
Step 2	Verify the flow-control configuration.	show port flowcontrol

This example shows how to turn on transmit and receive flow control and verify the flow-control configuration:

Console> (enable) set port flowcontrol 3/1 send on

Port 3/1 will send flowcontrol to far end.

Console> (enable) set port flowcontrol 3/1 receive on

Port 3/1 will require far end to send flow control

Console> (enable) show port flowcontrol

Port  Send-Flowcontrol  Receive-Flowcntl  RxPause  TxPause

      Admin   Oper      Admin   Oper

----- ----------------  ----------------  -------  -------

 3/1  on      disagree  on      disagree  0        0

 3/2  off     off       off     off       0        0

 3/3  desired on        desired off       10       10

Console> (enable)

Enabling and Disabling Port Negotiation

To enable port negotiation, perform this task in privileged mode:

	Task	Command
Step 1	Enable port negotiation.	set port negotiation mod/port enable
Step 2	Verify the port negotiation configuration.	show port negotiation [mod/port]

This example shows how to enable port negotiation and verify the configuration:

Console> (enable) set port negotiation 2/1 enable

Port 2/1 negotiation enabled

Console> (enable) show port negotiation 2/1

Port   Link Negotiation

-----  ----------------

 2/1   enabled

Console> (enable)

To disable port negotiation, perform this task in privileged mode:

	Task	Command
Step 1	Disable port negotiation.	set port negotiation mod/port disable
Step 2	Verify the port negotiation configuration.	show port negotiation [mod/port]

This example shows how to disable port negotiation and verify the configuration:

Console> (enable) set port negotiation 2/1 disable

Port 2/1 negotiation disabled

Console> (enable) show port negotiation 2/1

Port   Link Negotiation

-----  ----------------

 2/1   disabled

Console> (enable)

Changing the Default Port Enable State

---

Note Changing the default port enable state applies to all port types, not just Ethernet.

---

When you enter the clear config all command or in the event of a configuration loss, all ports collapse into VLAN 1. This situation might cause a security and network instability problem. Entering the set default portstatus command puts all ports into a disable state and blocks the traffic flowing through the ports during a configuration loss. You can then manually configure the ports back to the enable state.

The default port status configuration is stored on the chassis. The configuration is tied to a chassis and not to the supervisor engine. The clear config all command uses this setting to determine whether ports should be enabled or disabled when returning to default configuration. The clear config all command does not change the default port status setting on the chassis. The output of the show config command shows the current default port status configuration.

To change the port enable state, perform this task in privileged mode:

	Task	Command
Step 1	Change the port enable state.	set default portstatus {enable | disable}
Step 2	Display the port enable state.	show default

This example shows how to change the default port enable state from enabled to disabled:

Console> (enable) set default portstatus disable

Default port status set to disable.

Console> (enable) 

This example shows how to display the port enable state:

Console> (enable) show default

portstatus: disable

Console> (enable)

Setting the Port Debounce Timer

You can set the port debounce timer on a per-port basis for Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet ports. When you set the port debounce timer, the switch delays notifying the main processor of a link change that can decrease traffic loss due to network reconfiguration.

---

Caution Enabling the port debounce timer causes link up and link down detections to be delayed, resulting in loss of data traffic during the debouncing period. This situation might affect the convergence and reconvergence of various Layer 2 and Layer 3 protocols.

---

Table 4-4 lists the time delay that occurs before the switch notifies the main processor of a link change before and after the switch enables the debounce timer.

Table 4-4 Port Debounce Timer Delay Time 

Port Type	Debounce Timer Disabled	Debounce Timer Enabled
10BASE-FL ports	300 milliseconds	3100 milliseconds
10/100BASE-TX ports	300 milliseconds	3100 milliseconds
100BASE-FX ports	300 milliseconds	3100 milliseconds
10/100/1000BASE-TX ports	300 milliseconds	3100 milliseconds
1000BASE-TX ports	300 milliseconds	3100 milliseconds
Fiber Gigabit Ethernet ports	10 milliseconds	100 milliseconds
10-Gigabit Ethernet ports	10 milliseconds	100 milliseconds

To set the debounce timer on a port, perform this task in privileged mode:

	Task	Command
Step 1	Enable the debounce timer for a port.	set port debounce mod num/port num {enable | disable}
Step 2	Verify that the debounce timer of the port is configured correctly.	show port debounce [mod | mod_num/port_num]

This example shows how to enable the debounce timer on port 2/1:

Console> (enable) set port debounce 2/1 enable

Debounce is enabled on port 2/1

Warning: Enabling port debounce causes Link Up/Down detections to be delayed.

It results in loss of data traffic during debouncing period, which might

affect the convergence/reconvergence of various Layer 2 and Layer 3 protocols.

Use with caution.

Console> (enable)

This example shows how to display the per-port debounce timer settings:

Console> (enable) show port debounce

Port   Debounce link timer

-----  ---------------

 2/1   enable

 2/2   disable

Console> (enable)

Modifying the Port Debounce Timer Setting

---

Note Modifying the port debounce timer setting is possible only on fiber Gigabit Ethernet ports.

---

You can increase the port debounce timer value in increments of 100 up to 5000 milliseconds. You do not need to enable the debounce timer on the port before adjusting the timer value. Specifying any timer value that is greater than the default value in the disabled state enables the debounce timer.

To modify the port debounce timer setting on a port, perform this task in privileged mode:

	Task	Command
Step 1	Modify the port debounce timer setting.	set port debounce mod num/port num delay time
Step 2	Verify that the port debounce timer setting has been modified.	show port debounce [mod | mod_num/port_num]

This example shows how to modify the port debounce timer setting on port 2/1:

Console> (enable) set port debounce 2/1 delay 500

Debounce time for port 2/1 set to 500 ms.

Warning:Enabling port debounce causes Link Up/Down detections to be delayed.

It results in loss of data traffic during debouncing period, which might

affect the convergence/reconvergence of various Layer 2 and Layer 3 protocols.

Use with caution.

Console> (enable) 

This example shows how to display the per-port debounce timer setting on port 2/1:

Console> (enable) show port debounce 2/1

Port   Debounce link timer

-----  -------------------

 2/1   enabled (500 ms)

Console> (enable) 

Configuring a Timeout Period for Ports in errdisable State

A port is in errdisable state if it is enabled in NVRAM but is disabled at runtime by any process. For example, if UniDirectional Link Detection (UDLD) detects a unidirectional link, the port shuts down at runtime. However, because the NVRAM configuration for the port is enabled (you have not disabled the port), the port status is shown as errdisable.

If a port goes into errdisable state, it is reenabled automatically after a selected time interval. With the timeout enhancement, you can manually prevent a port from being enabled by setting the errdisable timeout for that port to disable using the set port errdisable-timeout mod/port disable command.

A global timer is maintained for all ports. At every t seconds, where t is the user-configurable timeout, a process checks to see if any ports are in errdisable state. If there are ports in errdisable state, only those ports that have errdisable timeout set (enabled) are reenabled through SCP messages.

By default, all errdisabled ports are reenabled when the global timer times out.

A port enters errdisable state for the following reasons (these reasons appear as configuration options within the set errdisable-timeout enable command):

•ARP inspection

•Broadcast suppression

•BPDU port-guard

•CAM monitor

•Channel misconfiguration

•Crossbar failure

•Duplex mismatch

•Layer 2 protocol tunnel misconfiguration

•Layer 2 protocol tunnel threshold exceeded

•Layer 2 protocol tunnel CDP threshold exceeded

•Layer 2 protocol tunnel STP threshold exceeded

•Layer 2 protocol tunnel VTP threshold exceeded

•Link errors RX threshold exceeded

•Link errors TX threshold exceeded

•UDLD

•Other (reasons other than the above)

•All (apply errdisable timeout for all of the above reasons)

You can enable or disable errdisable timeout for each of the above listed reasons. If you specify "other," all ports that are errdisabled by causes other than the reasons listed are enabled for errdisable timeout. If you specify "all," all ports that are errdisabled for any reason are enabled for errdisable timeout.

The errdisable feature is disabled by default. The default interval for enabling a port is 300 seconds. The allowable interval range is 30 to 86400 seconds (30 seconds to 24 hours).

To enable and configure the timeout period for ports in the errdisable state, perform these tasks in privileged mode:

Task	Command
Prevent a port from being reenabled at timeout after it goes into the errdisable state.	set port errdisable-timeout mod/port disable
Enable errdisable timeout for the BPDU guard causes.	set errdisable-timeout enable bpdu-guard
Enable errdisable timeout for all causes.	set errdisable-timeout enable all
Set the errdisable timeout interval.	set errdisable-timeout interval interval
Display the errdisable timeout configuration.	show errdisable-timeout

This example shows how to prevent port 3/3 from being reenabled at timeout after it goes into the errdisable state:

Console> (enable) set port errdisable-timeout 3/3 disable

Successfully disabled errdisable-timeout for port 3/3.

Console> (enable) 

This example shows how to enable errdisable timeout for BPDU guard causes:

Console> (enable) set errdisable-timeout enable bpdu-guard

Successfully enabled errdisable-timeout for bpdu-guard.

Console> (enable) 

This example shows how to enable errdisable timeout for all causes:

Console> (enable) set errdisable-timeout enable all

Successfully enabled errdisable-timeout for all.

Console> (enable) 

This example shows how to set the errdisable timeout interval to 450 seconds:

Console> (enable) set errdisable-timeout interval 450

Successfully set errdisable timeout to 450 seconds.

Console> (enable) 

This example shows how to display the errdisable timeout configuration:

Console> (enable) show errdisable-timeout

ErrDisable Reason                       Timeout Status

--------------------------------------- --------------

arp-inspection                          enable

bcast-suppression                       enable

bpdu-guard                              enable

cam-monitor                             enable

channel-misconfig                       enable

crossbar-fallback                       enable

duplex-mismatch                         enable

gl2pt-ingress-loop                      enable

gl2pt-threshold-exceed                  enable

gl2pt-cdp-threshold-exceed              enable

gl2pt-stp-threshold-exceed              enable

gl2pt-vtp-threshold-exceed              enable

link-rxcrc                              enable

link-txcrc                              enable

udld                                    enable

other                                   enable

Interval: 450 seconds

Port  ErrDisable Reason    Port ErrDisableTimeout  Action on Timeout

----  -------------------  ----------------------  -----------------

Console> (enable) 

Configuring Automatic Module Shutdown

When you enable automatic module shutdown, you can manage your network connectivity issues. A module that frequently resets itself can disrupt traffic load balancing. By enabling the automatic module shutdown, you can disable a module that continually resets due to any hardware or software problems and limit the number of times that the module resets itself before shutting down completely.

You can also shut down a module manually using the set module disable or the set module power down commands.

After the module shuts down, you must reenable the module manually.

By default, automatic module shutdown is disabled. When you enable automatic module shutdown, the default is that the module can reset itself three times within two minutes.

You must configure these two parameters before an automatic shutdown can occur:

•Frequency—Allows you to specify the threshold value for an automatic module shutdown. When the number of resets reaches the value that is assigned to this option, the Ethernet module can perform an automatic shutdown.

•Period—Allows you to specify the time period in which the number of resets must occur. The period is measured from one of these conditions:

–When the switch first comes up

–When the supervisor engine performs a switchover

–When the Ethernet module is powered up

–When the module's autoshut counters are cleared

When the frequency threshold is reached and occurs within the defined period, the Ethernet module automatically shuts down and this sample syslog message is displayed:

%SYS-5-MOD_AUTOSHUT: Module 2 shutdown automatically, reset 4 times in last 5 minutes due to inband failure

When the frequency threshold is reached and occurs outside the defined period, the module does not automatically shut down and this sample syslog message is displayed:

%%SYS-4-MOD_AUTOSHUT_SLOW:Module 1 reset frequency exceeded threshold but over 46 mins. Hence NOT powering down module

The run-time variable states for the Ethernet module do not synchronize with the standby supervisor engine. The output of the show autoshut command on a standby supervisor engine does not track with the number of resets or the reasons for the resets. If the module is powered down by the autoshut command, the output stays the same.

You do not have to enable an automatic module shutdown in order to track the number of resets. You can track resets even if you do not enable an automatic module shutdown.

The runtime counters are cleared only for these conditions:

•When you enter the clear autoshut command

•When the switch resets

•At module power up

•At supervisor engine switchover

---

Note An automatic module shutdown is supported on Ethernet modules only.

---

To enable and configure an automatic module shutdown, perform one of these tasks in privileged mode:

Task	Command
Enable an automatic module shutdown on a module.	set module autoshut enable mod num
Disable an automatic module shutdown on a module.	set module autoshut disable mod num
Set the threshold of the number of times that the module can reset itself.	set autoshut frequency num
Set the period (in minutes) over which the frequency is valid.	set autoshut period minutes
Clear the run-time counters on a specific module.	clear autoshut counters mod num
Reset the autoshut frequency to the default setting.	clear autoshut frequency
Reset the autoshut period to the default setting.	clear autoshut period
Display the automatic module shutdown configuration and current status information.	show autoshut

This example shows how to enable an automatic module shutdown on a module:

Console> (enable) set module autoshut enable 2

This example shows how to disable an automatic module shutdown on a module:

Console> (enable) set module autoshut disable 2

This example shows how to set the threshold of the number of times that the module can reset itself:

Console> (enable) set autoshut frequency 4

This example shows how to set the period (in minutes) over which the frequency is valid:

Console> (enable) set autoshut period 3

This example shows how to clear the run-time counters on a specific module:

Console> (enable) clear autoshut counters 3

Automatic shutdown counters cleared for module 3

Console> (enable) 

This example shows how to reset the automatic module shutdown frequency to the default setting:

Console> (enable) clear autoshut frequency

This example shows how to reset the automatic module shutdown period to the default setting:

Console> (enable) clear autoshut period

This example shows how to display the automatic module shutdown configuration and current status information:

Console> (enable) show autoshut

AutoShut Frequency:     3 times

AutoShut Period:        5 minutes

Mod Autoshut Current  Number Reason for last Time of last reset

num status   status   resets reset

--- -------- -------- ------ ---------------- -------------------------

1   NA       ok      -      -               -

2   enabled  shutdown 4      inband failure  Mon Jul 14 2003, 22:55:45

3   disabled ok      0      None            -

4   enabled  ok       1     scp failure      Mon Jul 14 2003, 21:03:17

Console> (enable) 

Configuring Port Error Detection

---

Note All ports in an EtherChannel should have the same port error detection settings.

---

To enable or disable port error detection on a port, perform this task in privileged mode (the default port setting for inerrors, RXCRC, and TXCRC is disabled):

	Task	Command
Step 1	Enable or disable port error detection on a port.	set port errordetection mod/port {inerrors | rxcrc | txcrc} {disable | enable}
Step 2	Verify the port configuration.	show port errordetection [mod | mod/port]

This example shows how to enable RXCRC port error detection on port 3/1:

Console> (enable) set port errordetection 3/1 rxcrc enable

Port(s)  3/1 set to errordetection rxcrc enable.

Console> (enable) show port errordetection 3/1

Port   Rxcrc    Txcrc

-----  -------- --------

 3/1   enabled  disabled

Console> (enable) 

Configuring Redundant Flex Links

The redundant flex links provide an alternative solution to the Spanning Tree Protocol (STP) by allowing users to disable STP and still provide link-level redundancy. The redundant flex links provide a link backup capability with rapid switchover redundancy. Flex link redundancy allows you to specify two ports to form the redundant link capability. You configure one port as the active port and the other port as the backup or peer port. The active port is in the forwarding state while the backup port is in the blocking state and does not allow traffic to pass through.

When the active port of the flex links experiences a failure, the MAC addresses are flushed and flooded. The backup port of the flex links learns the MAC addresses and restores connectivity. The failover convergence time depends on the number of VLANs and the number of MAC addresses. You cannot enable STP on the flex-link ports but you can run STP on other ports in the switch.

---

Tip We recommend that you use redundant flex links for configurations that have multiple Layer 2 access switches with common VLANs that are connected to a Layer 2 concentrator switch through two uplink ports.

---

These sections describe how to configure redundant flex links on the Catalyst 6500 series switches:

•Redundant Flex Link Configuration Guidelines and Restrictions

•Specifying the Active and Backup Ports for the Flex Links

•Displaying the Port Configuration of the Flex Links