Cisco Catalyst 3750 Series Switches

Release Notes for the Catalyst 3750 Switch, Cisco IOS Release 12.1(11)AX

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Release Notes for the Catalyst 3750 Switch Cisco IOS Release 12.1(11)AX

Table Of Contents

Release Notes for the Catalyst 3750 Switch
Cisco IOS Release 12.1(11)AX


System Requirements

Hardware Supported

Software Compatibility

Creating Clusters with Different Releases of IOS Software

Downloading Software

Determining the Software Version and Feature Set

Determining Which Files to Use

Upgrading a Switch by Using CMS

Upgrading a Switch by Using the CLI

Recovering from a Software Failure

Installation Notes

New Features

New Hardware Features

New Software Features

Limitations and Restrictions

IOS Limitations and Restrictions

Cluster Limitations and Restrictions

CMS Limitations and Restrictions

Important Notes

Switch Stack Notes

IOS Notes

Cluster Notes

CMS Notes

Open Caveats

Open IOS Caveats

Open CMS Caveats

Related Documentation

Obtaining Documentation

Documentation CD-ROM

Ordering Documentation

Documentation Feedback

Obtaining Technical Assistance

Technical Assistance Center

Cisco TAC Website

Cisco TAC Escalation Center

Obtaining Additional Publications and Information

Release Notes for the Catalyst 3750 Switch
Cisco IOS Release 12.1(11)AX

May 2003

The Cisco IOS Release 12.1(11)AX runs on all Catalyst 3750 switches. Catalyst 3750 switches support stacking through Cisco StackWise technology. Unless otherwise noted, the term switch refers to a standalone switch and to a switch stack.

These release notes include important information about this Cisco IOS release and any limitations, restrictions, and caveats that apply to it. Verify that these release notes are correct for your switch:

If you are installing a new switch, refer to the IOS release label on the rear panel of your switch.

If your switch is on, use the show version privileged EXEC command. See the "Determining the Software Version and Feature Set" section.

If you are upgrading to a new release, refer to the software upgrade filename for the software version.

For the complete list of Catalyst 3750 switch documentation, see the "Related Documentation" section.

You can download the switch software from these sites:

(for registered users with a login password)

(for nonregistered users)

This software release is part of a special release of Cisco IOS software that is not released on the same 8-week maintenance cycle that is used for other platforms. As maintenance releases and future software releases become available, they will be posted to (previously Cisco Connection Online [CCO]) in the Cisco IOS software area.


This information is in the release notes:

"System Requirements" section

"Downloading Software" section

"Installation Notes" section

"New Features" section

"Limitations and Restrictions" section

"Important Notes" section

"Open Caveats" section

"Related Documentation" section

"Obtaining Documentation" section

"Obtaining Technical Assistance" section

System Requirements

These are the system requirements for this software release:

"Hardware Supported" section

"Software Compatibility" section

Hardware Supported

Table 1 lists the hardware supported by this software release.

Table 1 Supported Hardware 


Catalyst 3750-24TS

24 10/100 Ethernet ports and 2 small form-factor pluggable (SFP) module slots

Catalyst 3750G-24T

24 10/100/1000 Ethernet ports

Catalyst 3750G-24TS

24 10/100/1000 Ethernet ports and 4 SFP module slots

Catalyst 3750-48TS

48 10/100 Ethernet ports and 4 SFP module slots

SFP modules

1000BASE-SX and 1000BASE-LX

Redundant power system

Cisco RPS 300 Redundant Power System for the Catalyst 3750G-24TS, 3750G-24T, and 3750-48TS switch models (not supported on the Catalyst 3750-24TS switch)

Cisco RPS 675 Redundant Power System for the entire Catalyst 3750 switch family

Software Compatibility

For information about the recommended platforms for web-based management, operating systems and browser support, Java plug-in guidelines and installation procedures, refer to the Catalyst 3750 Switch Hardware Installation Guide.

Creating Clusters with Different Releases of IOS Software

When a cluster consists of a mixture of Catalyst switches, we strongly recommend using only Catalyst 3750 switches as the command and standby command switches. The Catalyst 3750 switch can be part of a cluster as a standalone switch or as a switch stack. In a cluster, a switch stack is treated as a single entity.

When the command switch is a Catalyst 3750 switch, all standby command switches must also be Catalyst 3750 switches. The Catalyst 3750 switch that has the latest software should be the command switch. If the command switch is a Catalyst 3750 Gigabit Ethernet switch and the standby command switch is a Catalyst 3750 Fast Ethernet switch, command switch port speeds are reduced if the standby command switch takes over.

Table 2 lists the cluster capabilities and software versions for the switches. The switches are listed in the order of highest to lowest end switch. A lower-end switch cannot be the command switch of a switch listed above it in the table (for example, a Catalyst 2950 switch cannot be the command switch of a cluster that has Catalyst 2970 or Catalyst 3550 switches.)

Table 2 Switch Software and Cluster Capability

IOS Release
Cluster Capability

Catalyst 3750


Member or command switch

Catalyst 3550

12.1(4)EA1 or later

Member or command switch

Catalyst 2970


Member or command switch

Catalyst 2950

12.1(5.2)WC(1) or later

Member or command switch

Catalyst 2955

12.1(12c)EA1 or later

Member or command switch

Catalyst 3500 XL

12.0(5.1)XU or later

Member or command switch

Catalyst 2950

12.0(5.2)WC(1) or later

Member or command switch

Catalyst 2900 XL (8-MB switches)

12.0(5.1)XU or later

Member or command switch

Catalyst 2900 XL (4-MB switches)

11.2(8.5)SA6 (recommended)

Member switch only1

Catalyst 1900 and 2820

9.00(-A or -EN) or later

Member switch only

1 Catalyst 2900 XL (4-MB) switches appear in the front-panel and topology views of the Cluster Management Suite (CMS). However, CMS does not support configuration or monitoring of these switches.

Some versions of the Catalyst 2900 XL software do not support clustering, and if you have a cluster with switches that are running different versions of IOS software, software features added on the latest release might not be reflected on switches running the older versions. For example, if you start CMS on a Catalyst 2900 XL switch running Release 11.2(8)SA6, the windows and functionality can be different from a switch running Release 12.0(5)WC(1) or later.

Note The CMS is not forward-compatible, which means that if a member switch is running a software version that is newer than the release running on the command switch, the new features are not available on the member switch. If the member switch is a new device supported by a software release that is later than the software release on the command switch, the command switch cannot recognize the member switch, and it is displayed as an unknown device in the Front Panel view. You cannot configure any parameters or generate a report through CMS for that member; instead, you must launch the Device Manager application to configure and to obtain reports for that member.

Downloading Software

These are the procedures for downloading software:

"Determining the Software Version and Feature Set" section

"Determining Which Files to Use" section

"Upgrading a Switch by Using CMS" section

"Upgrading a Switch by Using the CLI" section

"Recovering from a Software Failure" section

Note Before downloading software, read this section for important information.

Determining the Software Version and Feature Set

The Cisco IOS image is stored as a .bin file in a directory that is named with the Cisco IOS release. A subdirectory contains the files needed for web management. The image is stored on the system board Flash device (flash:).

You can use the show version privileged EXEC command to see the software version that is running on your switch. The second line displays C3750-I5-M for the enhanced multilayer software image (EMI) or C3750-I9-M for the standard multilayer software image (SMI).

Note Although the show version output always shows the software image running on the switch (Layer 2 or Layer 2/3), the model name shown at the end of this display is the factory configuration (SMI or EMI) and does not change if you upgrade the software image.

You can also use the dir filesystem: privileged EXEC command to see the directory names of other software images that you might have stored in Flash memory.

Determining Which Files to Use

The upgrade procedures in these release notes describe how to perform the upgrade by using a combined .tar file. This file contains both the IOS image file and the files needed for the CMS. You must use the combined .tar file to upgrade the switch through the CMS. To upgrade the switch through the CLI, use the .tar file and the archive download-sw privileged EXEC command.

Table 3 lists the software filenames for this software release.

Table 3 Cisco IOS Software Image Files for Catalyst 3750 Switches 




IOS SMI image file and CMS files.
This image has Layer 2+ features including access control lists (ACLs), quality of service (QoS), static routing, and the Routing Information Protocol (RIP).


IOS EMI image file and CMS files.
This image has both Layer 2+ and full Layer 3 features. It includes Layer 2+ features and full Layer 3 routing (IP unicast routing, IP multicast routing, and fallback bridging). To distinguish it from the Layer 2+ static routing and RIP, the EMI includes protocols such as the Enhanced Interior Gateway Routing Protocol (EIGRP) and Open Shortest Path First (OSPF) Protocol.

Upgrading a Switch by Using CMS

You can upgrade switch software by using CMS. From the menu bar, select Administration > Software Upgrade. For detailed instructions, click Help.

Upgrading a Switch by Using the CLI

This procedure is for copying the combined .tar file to the Catalyst 3750 switch. You copy the file to the switch from a TFTP server and extract the files. You can download an image file and replace or keep the current image.

To download software, and if necessary, the TFTP server application, follow these steps:

Step 1 Use Table 3 to identify the file that you want to download.

Step 2 Download the software image file.

If you have a SmartNet support contract, go to this URL and log in to download the appropriate files:

If you do not have a SmartNet contract, go to this URL and follow the instructions to register on and download the appropriate files:

To download the SMI and EMI files, select Catalyst 3750 software.

Step 3 Download the Cisco TFTP server from the URL link from Step 2, if necessary. The information on this page describes how to download and configure the TFTP server.

Step 4 Copy the image to the appropriate TFTP directory on the workstation, and make sure the TFTP server is properly configured.

For more information, refer to Appendix B in the software configuration guide for this release.

Step 5 Log in to the switch through the console port or a Telnet session.

Step 6 Check your VLAN 1 configuration by using the show interfaces vlan 1 privileged EXEC command, and verify that VLAN 1 is part of the same network as the TFTP server. (Check the Internet address is line near the top of the display.)

Step 7 Download the image file from the TFTP server to the switch. If you are installing the same version of software that is currently on the switch, overwrite the current image by using this privileged EXEC command:

archive download-sw /overwrite /reload tftp:[[//location]/directory]/image-name.tar

The /overwrite option overwrites the software image in Flash memory with the downloaded one.

The /reload option reloads the system after downloading the image unless the configuration has been changed and not been saved.

For //location, specify the IP address of the TFTP server.

For /directory/image-name.tar, specify the directory (optional) and the image to download. Directory and image names are case sensitive.

This example shows how to download an image from a TFTP server at and to overwrite the image on the switch:

Switch# archive download-sw /overwrite tftp://

You can also download the image file from the TFTP server to the switch and keep the current image by replacing the /overwrite option with the /leave-old-sw option.

Recovering from a Software Failure

Switch software can be corrupted during an upgrade, by downloading the wrong file to the switch, and by deleting the image file. In all of these cases, the switch does not pass the power-on self-test (POST), and there is no connectivity. You can use the XMODEM protocol to recover from this failure.

For detailed recovery procedures, refer to the "Troubleshooting" chapter in the software configuration guide for this release.

Installation Notes

You can assign IP information to your switch by using these methods:

The setup program (Refer to the Catalyst 3750 Switch Hardware Installation Guide.)

The Dynamic Host Configuration Protocol (DHCP)-based autoconfiguration (Refer to the Catalyst 3750 Switch Software Configuration Guide.)

Manually assigning an IP address (Refer to the Catalyst 3750 Switch Software Configuration Guide.)

New Features

These are the new supported hardware and the new software features provided this release:

"New Hardware Features" section

"New Software Features" section

New Hardware Features

For a list of all supported hardware, see the "Hardware Supported" section.

New Software Features

This release is the first software release for the Catalyst 3750 switch. For a detailed list of key features for this software release, refer to the Catalyst 3750 Switch Software Configuration Guide.

Limitations and Restrictions

You should review this section before you begin working with the switch. These are known limitations that will not be fixed, and there is not always a workaround. Some features might not work as documented, and some features could be affected by recent changes to the switch hardware or software.

These are the limitations and restrictions:

"IOS Limitations and Restrictions" section

"Cluster Limitations and Restrictions" section

"CMS Limitations and Restrictions" section

IOS Limitations and Restrictions

These limitations apply to IOS configuration:

Non-reverse-path forwarded (RPF) IP multicast traffic to a group that is bridged in a VLAN is leaked onto a trunk port in the VLAN even if the port is not a member of the group in the VLAN, but it is a member of the group in some other VLAN. Because unnecessary traffic is sent on the trunk port, it needlessly reduces the bandwidth of the port. There is no workaround for this problem because non-RPF traffic is continuous in certain topologies. As long as the trunk port is a member on a trunk port in at least one VLAN, this problem for the non-RPF traffic occurs. (CSCdu25219)

If the number of multicast routes and Internet Group Management Protocol (IGMP) groups are more than the maximum number specified with the show sdm prefer global configuration command, the traffic received on unknown groups is flooded in the received VLAN even though the show ip igmp snooping multicast-table privileged EXEC command output shows otherwise. The workaround is to reduce the number of multicast routes and IGMP snooping groups to less than the maximum supported value. (CSCdy09008)

After the stack master switch failover and when the previous stack master rejoins the stack, some Layer 3 configuration on routed port interfaces belonging to the previous stack master might be lost (for example, the IP address, bridge groups, and so forth). This problem occurs under these conditions:

When the configuration of the stack has been modified but not saved.

The stack master switch fails, and a new switch in the stack is elected to become the new stack master.

The previous stack master rejoins the stack.

There is at least one port on the previous stack master physically configured as a routed port with some Layer 3 configuration.

The workaround for this problem is to save the configuration by using the write memory privileged EXEC command. If the problem has already occurred, reconfigure the lost settings on the routed port. (CSCdy29217)

If the switch stack is a designated bridge in the LAN and another switch is connected to the switch stack through redundant links and has one of these redundant ports in a blocking state, sometimes the spanning-tree state topology is not the same after configuration changes in the LAN. For example, if the root bridge has some ports that go down and then come back up, the switch stack might no longer be a designated bridge after the spanning-tree states stabilizes. Another switch in the LAN that had blocked ports might become the designated bridge. In some situations, the designated bridge selection behavior is not deterministic. The workaround is to shut down the root port or the blocked port on the switch stack by using the shutdown interface configuration command and to bring the same port up later by using the no shutdown interface configuration command. (CSCdy40828)

An egress SPAN copy of routed unicast traffic might show an incorrect destination MAC address on both local and remote SPAN sessions. This limitation does not apply to bridged packets. The workaround for local SPAN is to use the replicate option. For a remote SPAN session, there is no workaround. This is a hardware limitation. (CSCdy72835)

Egress SPAN routed packets (both unicast and multicast) show the incorrect source MAC address. For remote SPAN packets, the source MAC address should be the MAC address of the egress VLAN, but instead the packet shows the MAC address of the remote SPAN (RSPAN) VLAN. For local SPAN packets with native encapsulation on the destination port, the packet shows the MAC address of VLAN 1. This problem does not appear with local SPAN when the encapsulation replicate option is used. This limitation does not apply to bridged packets. The workaround is to use the encapsulate replicate keywords in the monitor session global configuration command. Otherwise, there is no workaround. This is a hardware limitation. (CSCdy81521)

IGMP filtering is applied to packets that are forwarded through hardware. It is not applied to packets that are forwarded through software. Hence, with multicast routing enabled, the first few packets are sent from a port even when IGMP filtering is set to deny those groups on that port. There is no workaround. (CSCdy82818)

The Catalyst 3750 switch treats frames received with mixed encapsulation (802.1Q and Inter-Switch Link [ISL]) as frames with FCS errors, increments the error counters, and causes the LED to blink amber. This happens when an ISL-unaware device receives an ISL-encapsulated packet and forwards the frame to an 802.1Q trunk interface. There is no workaround. (CSCdz33708)

IP-option software-forwarded traffic is sometimes leaked unnecessarily on a trunk port. Suppose the trunk port in question is member of an IP multicast group in VLAN X, but it is not a member in VLAN Y. In VLAN Y, there is another port that has membership to the group, and VLAN Y is the output interface for the multicast route entry corresponding to the group. IP options traffic received on an input interface VLAN (other than VLAN Y) is unnecessarily sent on the trunk port in VLAN Y because the trunk port is forwarding in VLAN Y (even though the port has no group membership in VLAN Y). There is no workaround. (CSCdz42909)

When you use the ip access-group interface configuration command with a router ACL to deny access to a group in a VLAN, multicast data to the group that is received in the VLAN is always flooded in the VLAN regardless of IGMP group membership in the VLAN. This provides reachability to directly connected clients, if any, in the VLAN. The workaround is to not apply a router ACL set to deny access to a VLAN interface. Apply the security through other means; for example, apply VLAN maps to the VLAN instead of using a router ACL for the group. (CSCdz86110)

SNAP-encapsulated IP packets are dropped without an error message being reported at the interface. The switch does not support SNAP-encapsulated IP packets. There is no workaround. (CSCdz89142)

During periods of very high traffic, when two RSPAN source sessions are configured, the VLAN ID of packets in one RSPAN session might overwrite the VLAN ID of the other RSPAN session. If this occurs, packets intended for one RSPAN VLAN are incorrectly sent to the other RSPAN VLAN. This problem does not affect RSPAN destination sessions. The workaround is to configure only one RSPAN source session. (CSCea72326)

A Gigabit Ethernet connection between a SGMII (Serial Gigabit Media Independent Interface) port (3/4, 7/8, 11/12, 15/16, 19/20, and 23/24) and an Intel Pro/1000T Server Adapter NIC might loose connectivity on the Catalyst 3750G-24T and Catalyst 3750G-24TS switches. The link activates correctly, but might subsequently stop exchanging data. This is an Intel product defect. The workaround is to use RGMII (Reduced Gigabit Media Independent Interface) ports (1/2, 5/6, 9/10, 13/14, 17/18, and 21/22) instead of SGMII ports. Alternatively, use the speed 1000 interface configuration command to force the speed of the port to 1000. (CSCea77032)

The egress SPAN data rate might degrade when fallback bridging or multicast routing is enabled. The amount of degradation depends on the processor loading. Typically, the switch can egress SPAN up to 40,000 packets per second (64-byte packets). As long as the total traffic being monitored is below this limit, there is no degradation. However, if the traffic being monitored exceeds the limit, only a portion of the source stream is spanned. When this occurs, the following console message appears: Decreased egress SPAN rate. In all cases, normal traffic is not affected; the degradation limits only how much of the original source stream can be egress spanned. If fallback bridging and multicast routing are disabled, egress SPAN is not degraded. There is no workaround. If possible, disable fallback bridging and multicast routing. If possible, use ingress SPAN to observe the same traffic. (CSCeb01216)

Cluster Limitations and Restrictions

These limitations apply to cluster configuration:

When there is a transition from the cluster active command switch to the standby command switch, Catalyst 1900, Catalyst 2820, and Catalyst 2900 4-MB switches that are cluster members might lose their cluster configuration. You must manually add these switches back to the cluster.
(CSCds32517, CSCds44529, CSCds55711, CSCds55787, CSCdt70872)

When a Catalyst 2900 XL or Catalyst 3500 XL cluster command switch is connected to a Catalyst 3550 or to a Catalyst 3750 switch, the command switch does not find any cluster candidates beyond the Catalyst 3550 or the Catalyst 3750 switch if it is not a member of the cluster. You must add the Catalyst 3550 or the Catalyst 3750 switch to the cluster. You can then see any cluster candidates connected to it. (CSCdt09918)

If both the active command-switch and the standby command switch fail at the same time, the cluster is not automatically recreated. Even if there is a third passive command switch, it might not recreate all cluster members because it might not have all the latest cluster configuration information. You must manually recreate the cluster if both the active and standby command switches simultaneously fail. (CSCdt43501)

CMS Limitations and Restrictions

These limitations apply to CMS configuration:

Host names and Domain Name System (DNS) server names that contain commas on a cluster command switch, member switch, or candidate switch can cause CMS to behave unexpectedly. You can avoid this instability in the interface by not using commas in host names or DNS names. Do not enter commas when entering multiple DNS names in the IP Configuration tab of the IP Management window in CMS.

Access control entries (ACEs) that contain the host keyword precede all other ACEs in standard access control lists (ACLs). You can reposition the ACEs in a standard ACL with one restriction: No ACE with the any keyword or a wildcard mask can precede an ACE with the host keyword.

CMS performance degrades if the Topology View is open for several hours on a Solaris machine. The cause might be a memory leak. The workaround is to close the browser, reopen it, and launch CMS again. (CSCds29230)

If you are printing a Topology View or Front Panel View that contains many devices and are running Solaris 2.6 with JDK1.2.2, you might get an Out of Memory error message. The workaround is to close the browser, re-open it, and launch CMS again. Before you perform any other task, bring up the view that you want to print, and click Print in the CMS menu.(CSCds80920)

If a PC running CMS has low memory and CMS is running continuously for 2 to 3 days, the PC runs out of memory. The workaround is to relaunch CMS. (CSCdv88724)

When a VLAN or a range of VLANs is already configured and you specify a VLAN filter for a SPAN session, the current configuration for that session is overwritten with the new entry. Although the CLI appends new entries after the existing ones, CMS recreates the whole session, overwrites the current entry, and provides only a single VLAN filter per entry. The workaround is to use the CLI. It is the only method for specifying multiple VLANs for filtering in a SPAN session. (CSCdw93904)

CMS temporarily halts while starting with Netscape version 4.75 and Java Runtime Environment (JRE) 1.3.1 or 1.4.0 on Windows 98. This also happens with Netscape version 6.2 and JRE 1.3.1 on Windows 98. When you bring up CMS, it halts while determining network information. The workaround is to click once outside of the CMS window. Then CMS should proceed. (CSCdz69724)

When you add a new member with a username and password that is different from the existing cluster members username and password, CMS produces an exception error because of an authentication failure. The workaround is to add the new member without any username and password. When the new member is added to the cluster, remove the existing username and password from the Username and Password fields, enter a new username and password, and then apply it to all cluster members. (CSCdz07957)

When the Link Graphs application has run for hours displaying packet drop and error information, sometimes the X-axis crosses the Y-axis at a negative y value instead of at y = 0. This condition occurs with all supported operating systems, browsers, and Java plug-ins. There is no workaround. (CSCdz32584)

Important Notes

These are the important notes related to this software release:

"Switch Stack Notes" section

"IOS Notes" section

"Cluster Notes" section

"CMS Notes" section

Switch Stack Notes

Always power off a switch before adding or removing it from a switch stack.

IOS Notes

There are no IOS configuration notes to report.

Cluster Notes

There are no cluster configuration notes to report.

CMS Notes

These notes apply to CMS configuration:

If you use CMS on Windows 2000, it might not apply configuration changes if you change the enable password from the CLI during your CMS session. You have to restart CMS and enter the new password when prompted. Platforms other than Windows 2000 prompt you for the new enable password when it is changed.

CMS does not display QoS classes that are created through the CLI if these classes have multiple match statements. When using CMS, you cannot create classes that match more than one match statement. CMS does not display policies that have such classes.

If you use Internet Explorer Version 5.5 and select a URL with a nonstandard port at the end of the address (for example,, you must enter http:// as the URL prefix. Otherwise, you cannot launch CMS.

Within an ACL, you can change the sequence of ACEs that have the host keyword. However, because such ACEs are independent of each other, the change has no effect on the way the ACL filters traffic.

If you use the Netscape browser to view the CMS GUI and you resize the browser window while CMS is initializing, CMS does not resize to fit the window.

Resize the browser window again when CMS is not busy.

CMS does not start if the temporary directory on your computer runs out of memory. This problem can occur because of a bug in the 1.2.2 version of the Java plug-in. The plug-in creates temporary files in the directory whenever it runs CMS, and the directory eventually runs out of plug-in space.

The workaround is to remove all the jar_cache*.tmp files from the temporary directory. The path to the directory is different for different operating systems:

Solaris: /var/tmp
Windows NT and Windows 2000: \TEMP
Windows 95 and 98: \Windows\Temp

In the Front Panel view or the Topology view, CMS does not display error messages in read-only mode for these switches:

Catalyst 2900 XL or Catalyst 3500 XL member switches running Release 12.0(5)WC2 or earlier

Catalyst 2950 member switches running Release 12.0(5)WC2 or earlier

Catalyst 3550 member switches running Release 12.1(6)EA1 or earlier

In the Front Panel view, if the switch is running one of the previously listed software releases, the device LEDs do not appear. In the Topology view, if the member is a Long-Reach Ethernet (LRE) switch, the customer premises equipment (CPE) connected to the switch does not appear. The Bandwidth and Link graphs also do not appear in these views.

To view switch information, you need to upgrade the member switch software. For information about upgrading switch software, see the "Downloading Software" section.

Open Caveats

These are the open caveats with possible unexpected activity in this software release:

"Open IOS Caveats" section

"Open CMS Caveats" section

Open IOS Caveats

These are the severity 3 IOS configuration caveats:


The user-configured IP address is removed when the previously acquired Dynamic Host Configuration Protocol (DHCP) IP address lease expires.

This problem occurs under these conditions:

When the switch is booted without a configuration (no config.text file in Flash memory).

When the switch is connected to a DHCP server that is configured to give an address to it (the dynamic IP address is assigned to VLAN 1).

An IP address is configured on VLAN 1 before the dynamic address lease assigned to VLAN 1 expires.

The workaround is to reconfigure the lost IP address configuration by using the ip address interface configuration command on VLAN 1.


While in the interface-range configuration mode, if you use the no channel-group interface configuration command or change the channel-group mode by using the channel-group command, an assert-fail message with traceback information appears.

The workaround is to not remove a channel group or change the channel-group mode while in interface-range configuration mode.


When multicast VLAN registration (MVR) groups are added or deleted, the receiver port that joined the groups after the addition still receives traffic even after the group is deleted. The correct behavior is that MVR data traffic to the group should stop flowing to the receiver port immediately after the no mvr group ip-address global configuration command is entered.

The workaround is to disable MVR by using the no mvr global configuration command and then to re-enable it by using the mvr command. Add and delete the groups that have problems by using the mvr group ip-address and the no mvr group ip-address global configuration commands.


In a switch stack, if the stack master switch is reloaded at the same time that an EtherChannel link on a stack member goes down, a new stack master switch is elected but fails shortly thereafter.

There is no workaround.


When an output ACL for a VLAN is full, the switch drops all the packets routed or sent to that VLAN. Because of a hardware problem, the switch cannot use software to forward. This problem occurs for all Layer 3 features, such as unicast routing, multicast routing, and fallback bridging.

There is no workaround.


If there is a lot of SNMP polling activity and MAC notification traps being sent on the switch, entering the mac-address-table notification history-size value global configuration command to change the MAC address notification table history size might cause the switch to fail.

The workaround is to disable the MAC notification traps by using the no mac-address-table notification command, wait for 10 seconds, and then enter the mac-address-table notification history-size command. After entering this command, re-enable the MAC notification traps by using the mac-address-table notification command.


A broadcast storm occurs in a bridge group under these conditions:

When a port in the VLAN in which fallback bridging is enabled receives a non-IP packet with the bridge protocol data unit (BPDU) indicator bit set in the ISL header.

The destination MAC address has not been learned in the bridge group and at least one port in the VLAN is in the blocking state.

The broadcast storm ceases as soon as the MAC address is learned in the bridge group.

The workaround is to make sure that all ports in a VLAN that are participating in fallback bridging are in the forwarding state.


Known unicast (secured addresses) are flooded within a bridge group under these conditions:

If secure addresses are learned or configured on a port and the VLAN on this port is part of a bridge group, non-IP traffic destined to the secure addresses is flooded within the bridge group.

The workaround is to disable fallback bridging. To remove an interface from a bridge group and to remove the bridge group, use the no bridge-group bridge-group interface configuration command. Another workaround is to disable port security on all ports in all VLANs participating in fallback bridging by using the no switchport port-security interface configuration command.


When an undefined aggregate policer is configured in a policy-map, the switch automatically generates the wrong aggregate policer for it.

The workaround is to configure an aggregate policer by using the mls qos aggregate-policer global configuration command before configuring the policy-map.


When you are in policy-map class configuration mode and configure an aggregate policer with the police aggregate policy-map class configuration command, causing the number of aggregate policers to exceed 63, the aggregate policer is still retained in the policy map. This over-limit policer cannot be attached again and creates inconsistent behavior

The workaround is to manually delete the over-limit policer by using the no police aggregate aggregate-policer-name policy-map class configuration command.


Under some heavy load conditions with bridge groups and SPAN enabled (where the packets are dropped at the port because of flooding), the %SUPQ-4-CPUHB_RECV_STARVE message appears. This can be due to loops in the spanning trees. During this condition, the port output rate is reduced to recover from the condition. The message means that this condition has occurred.

The workaround is to check the traffic pattern and the configuration of the switch to see why the port is dropping packets. Reconfigure or change the traffic pattern. If this is not possible, reduce the port output line rate by using the srr-queue bandwidth limit 65 interface configuration command on the ports where heavy traffic is seen. If the message is not recurring, it was a transient condition, and the switch recovered from it.


An extended access list with permit or forward actions using Layer 4 information might incorrectly forward fragmented packets. The first packet of a fragmented packet is correctly forwarded by hardware, but subsequent packets with nonzero offsets are forwarded by software or dropped.

There is no workaround.


You cannot set the VTP mode to transparent(3) using SNMP.

The workaround is to set the VTP mode to transparent using the vtp mode transparent interface configuration command.


The switch can take several minutes to generate and optimize the forwarding rules after you configure a complex VLAN map. For example, a complex VLAN map might contain multiple sequences that use the same VLAN map ACL, where the individual ACL clauses include one or more deny clauses (nonterminating-not the last deny). During the optimization process, the switch might not respond to commands.

The workaround is to minimize the use of complex VLAN map ACLs. Otherwise, wait 10 to 15 minutes for the optimization to complete.


When snooping is disabled and a spanning tree loop exists, incoming IGMP report and leave messages generate a storm of such messages in the network.

The workaround is to enable snooping. Alternatively, shut down the blocked ports.


Gigabit Ethernet ports configured for RGMII mode (1/2, 5/6, 9/10, 13/14, 17/18, and 21/22) might fail an internal loopback test during system startup on the Catalyst 3750G-24T and Catalyst 3750G-24TS switches. If this occurs, the port is permanently shut down and unusable. On reboot, the port might operate normally.

The workaround is to use other ports until the next software release.


A routed port that uses an IP ACL might not correctly filter packets after an administrative shutdown and restart. The problem can occur after the following sequence:

An IP ACL is applied to a routed port using the ip access-group interface configuration command.

The routed port is shut down by using the shutdown interface configuration command.

The ACL is modified or another interface is changed between routed port and switched port using the switchport and no switchport interface configuration commands.

The routed port is re-enabled by issuing the no shutdown interface configuration command.

The workaround is to always remove the IP ACL from the routed port after an administrative shutdown and then reapply the IP ACL after re-enabling the port.


Gigabit Ethernet ports might have FCS errors when operating at Gigabit speeds on the Catalyst 3750G-24T and Catalyst 3750G-24TS switches. The FCS error rate for this condition is very low.

The workaround is to restart the ports by using the shutdown and then no shutdown interface configuration commands.


The RSPAN feature incorrectly spans all local link control packets with a destination MAC address of 0100.0CCC.CCCC on trunk ports that carry the RSPAN VLAN. As a result, trunk ports carrying the RSPAN VLAN incorrectly combine control packets from RSPAN source ports with normal local control packets. The resulting problems vary from confusing results to improper protocol operation. The following list describes problems that can occur with selected protocols:

Cisco Discovery Protocol (CDP) could provide incorrect information. For example, CDP could incorrectly list a neighbor switch that is actually a neighbor on the RSPAN source port.

Dynamic Trunking Protocol (DTP) could fail to work properly on trunks that are carrying the RSPAN VLAN.

Port Aggregration Protocol (PAgP) could fail to work properly on EtherChannels that are carrying the RSPAN VLAN.

VLAN Trunking Protocol (VTP) could incorrectly propagate VTP pruning messages on the wrong interface. For example, a pruning message intended for an RSPAN source port could also appear on the trunk port carrying the RSPAN VLAN.

Unidirectional Link Detection Protocol (UDLD) and any other protocol that uses 0100.00CC.CCCC as the destination MAC address could not operate properly on trunk ports that carry the RSPAN VLAN.

The following list describes workarounds:

If necessary, disable CDP by using the no cdp enable interface configuration command on all interfaces used as RSPAN sources.

Do not use DTP on trunks carrying the RSPAN VLAN. Instead, use the switchport trunk encapsulation encapsulation-type, switchport mode trunk, and switchport nonegotiate interface configuration commands to create an unconditional trunk and to disable DTP negotiation.

Do not use PAgP on trunks carrying the RSPAN VLAN. Instead, use the channel-group channel-number mode on interface configuration command to form the EtherChannel without negotiation.

Prune the RSPAN VLAN from all trunk ports where it is not needed. For example, by using the switchport trunk allowed vlan except rspan-vlan-id interface configuration command to exclude specific RSPAN VLANs.

Open CMS Caveats

These are the severity 3 CMS configuration caveats:


In the Voice VLAN window, you cannot configure a voice VLAN when the VLAN mode is set to dynamic desirable or dynamic auto.

The workaround is to configure the voice VLAN with static-access mode. In the Voice VLAN window, select the interface to modify, and click Modify to display the Modify Voice VLAN window. In the VLAN Mode drop-down list, select Static Access, and click OK. Then launch the VLAN window by selecting VLAN > VLAN from the menu bar. Click the Configure Ports tab. Select the port, and click Modify to launch the Modify Port Mode window. In the Administrative Mode drop-down list, select Trunk Desirable or Trunk Auto, and click OK.


Certain Simple Network Management Protocol (SNMP) traps are not shown on the SNMP Trap Managers tab even though they are configured. For example, suppose you click the Administration > SNMP > Trap Managers tab, create a trap manager, click the vlancreate and vlandelete checkboxes along with other traps, and click Apply. When you select the new trap manager entry in the Current Managers list, the vlancreate and vlandelete options are not shown.

There is no workaround.


In the Topology View, when you right-click a device in an expanded stack to display the Device Properties window, all devices are shown as having the model number of the stack master switch. This happens even if there are several model numbers within the stack. This condition occurs with all supported operating systems, browsers, and Java plug-ins.

There is no workaround.


From the Users and Passwords window (Administration > Users and Passwords), there is no provision for enabling or disabling the login for console or VTY lines. The line console 0 login global configuration command is not supported in CMS.

There is no workaround.


Whenever a given VLAN has multiple router ports associated with it, the IGMP Router tab on the IGMP Report window (Reports > Multicast > IGMP Report) shows only one router port, but it should show all router ports on a given VLAN.

The workaround is to obtain the same information from the Multicast Router Ports tab on the IGMP Snooping window by selecting Device > IGMP Snooping from the menu bar. This tab shows all the applicable router ports.


When you select the Device > QoS > Policies window and try to modify a policy, you might receive a null-pointer exception error, which prevents you from modifying the policy. The error happens if the policy uses a class that has an ACL match statement and the ACL is deleted.

The workaround is to remove the class from the policy.

CSCea26106 You might not be able to create or modify an EtherChannel if the ports in the EtherChannel do not meet these requirements:

Port group members must belong to the same set of VLANs and must be all static-access or all trunk ports. The native VLAN ID, trunk VLANs, and pruning VLANs must be the same for trunk ports.

Port monitoring (also known as Switched Port Analyzer [SPAN]), port security, 802.1X should not be enabled on the port.

Dynamic-access ports cannot be grouped.

The workaround is to make sure that the channel-group members belong to the same allowed range of VLANs and that members are either all static-access or all trunk ports. For all trunk ports, the native VLAN, allowed VLANs on the trunk, and the VLANs in the pruning-eligible list must be the same. Do not assign a port to an EtherChannel when SPAN, port security, or 802.1X is configured on the port. Dynamic-access ports cannot belong to a channel group.


The Refresh button of the CMS Inventory Report does not update the System Uptime.

The workaround is to click the Refresh icon on the browser toolbar instead.

Related Documentation

These documents provide complete information about the switch and are available from this site:

You can order printed copies of documents with a DOC-xxxxxx= number from the sites and from the telephone numbers listed in the "Obtaining Documentation" section.

Catalyst 3750 Switch Software Configuration Guide (order number DOC-7815164=)

Catalyst 3750 Switch Command Reference (order number DOC-7815165=)

Catalyst 3750 Switch System Message Guide (order number DOC-7815166=)

Cluster Management Suite (CMS) online help (available only from the switch CMS software)

Catalyst 3750 Switch Hardware Installation Guide (order number DOC-7815136=)

Cisco Small Form-Factor Pluggable Modules Installation Notes (not orderable but available on

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