Release Notes for the FastHub 400 10/100 Series, January 2003

These release notes include important information about the FastHub 400 10/100 series (hereafter referred to as the FastHub 400) and any limitations, restrictions, and caveats that apply to it.

The tracking numbers for some items in this document are added for your convenience.

Documentation Notes

The installation and configuration guide incorrectly lists the CISCO-SIBU-SIMPLE-UPGRADE-MIB.my MIB as a supported MIB. The hub does not support this MIB.

Limitations

The FastHub 400M can store up to 4096 MAC addresses in memory. The optional switched uplink modules can store up to 1536 MAC addresses. If there is excessive flooding of unicast packets on these devices, your hub or module might have reached its maximum. To clear the MAC address table, power-cycle the hub. [CSCdk90641]

Usage Guidelines

Some 400 FastHubs have improperly terminated 100-MB TXEN signal lines at the extension port. If this problem occurs when no extension module is present, 100-MB data can be corrupted. Firmware releases 1.00.02 and later detect the absence of an extension module and isolate the extension port from the hub.
You must purchase and use the FastHub 400 stacking cable (part number WS-C400-CAB-EXP) to create a hub stack of interconnected FastHub 400 models. Do not use any other cable for this purpose. You can order this cable from your Cisco representative or reseller.
A FastHub 400 does not support modem connections over a telephone line to a PC connected to another modem by a telephone line. To connect to a FastHub 400 using a modem, refer to your modem manual for the correct configuration command syntax. [CSCdk83978]
Before connecting a FastHub 400M model to a modem, configure your modem to ignore input from the data terminal equipment (DTE) during dial-out or dial-in. Without this precaution, there is a small chance that the modem could disconnect. Refer to your modem manual for the correct configuration command syntax. [CSCdk83009]

Stacking Guidelines

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

The stacking cable connectors are lockable. When you insert the stacking cable, be sure that it snaps into place.
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 management hub is referred to as the M1 hub. The secondary management hub is referred to as the M2 hub.
The M1 hub continuously stores the configuration settings for these stack elements:

Itself.
The three hubs that it has most recently managed (whether or not the hubs are currently being managed).
TX and FX switched uplink modules for itself and for each of the three hubs that it has most recently managed.

This means that if you remove a hub (other than the M1 hub) or module from the stack and later reinstall the same device, the M1 hub reconfigures that device with its former configuration in the stack. Whether or not this happens depends upon whether the stored configuration for that particular device has been retained by the M1 hub or overwritten in subsequent changes.

Stacking Example

In a stack of hubs where hub 1 is the FastHub 400 M1 hub and hubs 2, 3, and 4 are FastHub 400 unmanaged hubs, these conditions apply:

If you remove hub 3 and replace it with a new hub (hub A), the new hub keeps its default configuration. (See Table 1.)

Table 1

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

If hub 4 is removed for troubleshooting purposes and later reinstalled in the second position in the stack, the M1 hub recognizes the serial number of that hub as belonging to one of its saved configurations and applies the previously saved hub 4 configuration. (See Table 2.)

Table 2

Original Stack	Reinstalled	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)

Clearing the NVRAM of a Management Hub in a Redundant Stack

To reset the nonvolatile random-access memory (NVRAM) configuration settings of one or both management hubs in a redundant stack configuration, note the following guidelines.

When a second FastHub 400 managed hub is added to a stack, the new hub, referred to as the M2 hub, learns the saved configuration settings for the stack from the M1 hub. If the M1 hub fails, the M2 hub uses the saved configuration of the M1 hub.
The delete nvram command only resets the NVRAM of the M1 hub. If an M2 hub is connected to the stack, the contents of the M2 hub NVRAM will immediately be copied to the NVRAM of the M1 hub. To ensure you reset the NVRAM of a FastHub 400, use one of these methods:

To clear the NVRAM of the M1 hub, disconnect the stack cable between the M1 hub and the M2 hub, connect a console cable to the M1 hub, and use the delete nvram command.
To clear the NVRAM of the M2 hub, disconnect the stack cable between the M1 hub and the M2 hub, connect a console cable to the M2 hub, and use the delete nvram command. [CSCdk91393]

You must power down the stack before resetting either or both management hubs. To do this, unplug the stacking cable from the management hubs that you want to reset.
Connect the hub to a management station.
Power on the hub and access the command-line interface (CLI).
Refer to the online FastHub 400 10/100 Series Command Reference for information about accessing the CLI. See the "Obtaining Documentation" section of this document for information about locating this document through Cisco.com.
Use the CLI delete nvram command to reset either or both management hubs to their default values.
Refer to the online reference FastHub 400 10/100 Series Command Reference for more information about this command.
The management hub that is powered on first becomes the new M1 hub in the stack because the hub with the longest up time is by default the M1 hub.

Note If you delete the NVRAM configuration settings for one management hub and not the other, be sure to power on the management hub with the deleted configuration first. This prevents the redundant management hub from copying its saved configuration to the hub whose configuration you just deleted.

Resolved Caveats

Resolved Caveats in Release 1.00.08

The Cisco FastHub 400 is susceptible to Simple Network Management Protocol (SNMP) vulnerabilities. These vulnerabilities can be easily and repeatedly demonstrated with the use of the University of Oulu Secure Programming Group (OUSPG) "PROTOS" Test Suite for SNMPv1. The test suite is generally used to analyze a protocol and produce messages that probe various design limits within an implementation of a protocol. Test packets containing overly-long or malformed object identifiers and other combinations of exceptional values in various fields can be programmatically generated and then transmitted to a network device under test. The PROTOS test suite for SNMPv1, as distributed, contains approximately 53,000 individual test cases.

Resolved Caveats in Release 1.00.06

You no longer lose connectivity across the uplink module when moving to a new port on the same FastHub 400 or to a port on a different FastHub 400.

Resolved Caveats in Release 1.00.04

Resolved Caveats in Release 1.00.03

Using Cisco Discovery Protocol (CDP) with a FastHub 400M no longer occasionally locks the console.

Related Documentation

These documents provide complete information about the hub and are available from this Cisco.com site:

FastHub 400 10/100 Series Cabling and Start Up
FastHub 400 10/100 Series Installation and Configuration Guide
Installation Notes for the FastHub 400 10/100 Series Switched Uplink Modules
FastHub 400 10/100 Series Command Reference (online only)
FastHub 400 10/100 series Hub Manager online help

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