Release Notes for the Cisco 1538 Series Micro Hubs 10/100

February 17, 1999

These release notes provide information on the Cisco 1538 Series Micro Hubs 10/100 (hereafter referred to as the Micro Hub).

Usage Guidelines

You must use the supplied stacking cable (model number WS-C400-CAB-EXP) to interconnect Micro Hubs to create a hub stack.
The Cisco ConfigMaker CD that shipped with your hub does not support this device. Contact your Cisco representative or reseller to receive the correct version, or download the latest version from CCO.
Before connecting a Cisco 1538M managed hub to a modem, you should configure your modem to ignore input from the data terminal equipment (DTE) during dial-out or dial-in. Without this precaution, there is a slim chance that the modem could disconnect. Refer to your modem manual for the correct configuration command syntax.

Stacking Guidelines

When changing or moving units within a managed hub stack, note these configuration rules:

The stacking cables are not hot-swappable. You must power down the hub stack before connecting or disconnecting a stacking cable. If you connect or disconnect a stacking cable while the power is on, power cycle the stack to ensure correct stack management operation.
The primary managed hub (hereafter referred to as the M1 hub) in a stack will store the settings for itself and the most recent three hubs it has managed.

This means that if you remove a hub from the stack (other than the M1 hub) and later reinstall the same hub, that hub can assume its former configuration in the stack through the M1 hub. Whether or not this happens depends upon the number of hubs that have been added or exchanged between that hub's removal and its reinstallation into the stack.

For example, in a stack of hubs in which hub 1 is the Cisco 1538M M1 hub and hubs 2, 3, and 4 are Cisco 1538 manageable hubs, the following conditions would apply:

If you remove hub 3 and replace it with a new hub (hub A), the new hub would keep its default configuration:

Original Stack	New Stack
--------------	------------
Hub 1	Hub 1 (store M1)
Hub 2	Hub 2 (store 2)
(Hub 3) ---> Hub A --->	Hub 3 (store A: new)
Hub 4	Hub 4 (store 4)

If hub 4 was removed for troubleshooting purposes and later reinstalled in the second position in the stack, the M1 hub would recognize the serial number of that hub as belonging to one of its saved configurations and would apply the previously saved hub 4 configuration.

Original Stack	New Stack
--------------	------------
Hub 1	Hub 1 (store M1)
Hub 2 ---> Hub 4 --->	Hub 2 (store 4: saved)
Hub 3A	Hub 3 (store 2: saved)
(Hub 4)	Hub 4 (store 3A: saved)

When a second Cisco 1538M managed hub (M2 hub) is added to a stack, the new M2 hub learns the saved configuration settings for the stack from the M1 hub. If the M1 hub fails, the M2 hub would use the saved configuration of the M1 hub.

This means that if you want to reset the NVRAM configuration of a hub in a redundant configuration, follow these guidelines:

Whichever managed hub is powered on first becomes the new M1 hub in the stack, since the hub with the longest up time is by default the M1. If you delete the nvram configuration settings for one hub and not the other, be sure to power on the hub with the default configuration first. This will prevent the redundant managed hub from copying its saved configuration to the hub whose configuration you just cleared.
You must power down the stack and isolate the redundant managed hubs from one another before applying the delete nvram command. To do this, remove the stacking cable(s) from the hub, connect the isolated hub to a management station, power up the hub, and access the command-line interface (CLI). Refer to the online reference Cisco 1538 Series Micro Hub 10/100 Command Reference for more information about this command. See the "Cisco Connection Online" section of this release note for information about accessing this reference.

The stacking cable connectors are lockable. When you insert the stacking cable, be sure it snaps into place.

Cisco Connection Online

Cisco Connection Online (CCO) is Cisco Systems' primary, real-time support channel. Maintenance customers and partners can self-register on CCO to obtain additional information and services.

Available 24 hours a day, 7 days a week, CCO provides a wealth of standard and value-added services to Cisco's customers and business partners. CCO services include product information, product documentation, software updates, release notes, technical tips, the Bug Navigator, configuration notes, brochures, descriptions of service offerings, and download access to public and authorized files.

CCO serves a wide variety of users through two interfaces that are updated and enhanced simultaneously: a character-based version and a multimedia version that resides on the World Wide Web (WWW). The character-based CCO supports Zmodem, Kermit, Xmodem, FTP, and Internet e-mail, and it is excellent for quick access to information over lower bandwidths. The WWW version of CCO provides richly formatted documents with photographs, figures, graphics, and video, as well as hyperlinks to related information.

You can access CCO in the following ways:

WWW: http://www.cisco.com
WWW: http://www-europe.cisco.com
WWW: http://www-china.cisco.com
Telnet: cco.cisco.com
Modem: From North America, 408 526-8070; from Europe, 33 1 64 46 40 82. Use the following terminal settings: VT100 emulation; databits: 8; parity: none; stop bits: 1; and connection rates up to 28.8 kbps.

For a copy of CCO's Frequently Asked Questions (FAQ), contact cco-help@cisco.com. For additional information, contact cco-team@cisco.com.

Note If you are a network administrator and need personal technical assistance with a Cisco product that is under warranty or covered by a maintenance contract, contact Cisco's Technical Assistance Center (TAC) at 800 553-2447, 408 526-7209, or tac@cisco.com. To obtain general information about Cisco Systems, Cisco products, or upgrades, contact 800 553-6387, 408 526-7208, or cs-rep@cisco.com.

Documentation CD-ROM

Cisco documentation and additional literature are available in a CD-ROM package, which ships with your product. The Documentation CD-ROM, a member of the Cisco Connection Family, is updated monthly. Therefore, it might be more current than printed documentation. To order additional copies of the Documentation CD-ROM, contact your local sales representative or call customer service. The CD-ROM package is available as a single package or as an annual subscription. You can also access Cisco documentation on the World Wide Web at http://www.cisco.com, http://www-china.cisco.com, or http://www-europe.cisco.com.

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