Important Information about the LinkBuilder FMS Bridge/Management Module

Modified: 12/17/96

Important Information about the
LinkBuilder FMS Bridge/Management Module

The following information relates to the FMS II Bridge/Management Module (version 1.00) 3C16040, and should be read in conjunction with the user manual "How to Install and Use The LinkBuilder FMS II Bridge/Management Module" (Part number DUA1604-0AAA01).

A. Additional Installation Instructions

This information concerns the installation of the module into the FMS II unit, as described in Section 2.5 of the user manual.

Caution

During installation, both the insert/remove tab (C) and the lip on the connector must be facing towards the module's printed circuit board. This means that the connecting wires will be twisted, as shown in the illustration below. Failure to ensure the connector is correctly oriented can result in damage to the module when the unit is powered up.

B. The LinkBuilder FMS Agent, Version 2.02

1 Existing ISOVIEW customers will find a new version of the ISOVIEW Concise MIB for FMS on the 3Com bulletin boards. This gives access to the new FMS Agent version 2 functionality through the MIB Browser. The bulletin board telephone numbers are:

Australia +61 2 955 2073 Italy +39 2 273 00680 (fee required)

France +33 1 6986 6954 UK +44 442 278278

Germany +49 89 67281189 US +1 408 980 8204

2 On the VT100 Port Setup screen, the `Link State' and `Lost Links' fields are displayed for Thin Coax ports, but they do not apply to this type of port.

3 On the VT100 Repeater Statistics, Unit Statistics and Port Statistics screens, Short Events are counted as Runts.

4 On the VT100 Unit Setup screen, a unit configured as Disable on Boot will indicate `All Ports Disabled' in the `Unit Boot State' field, even if any ports have been selectively enabled via the VT100 Port Setup screen. This also applies if the unit is not Disable on Boot and some ports have been selectively disabled.

5 On the VT100 Port Resilience screen, the resilient link pair parameters are displayed when the pair creation was unsuccessful.

6 On the VT100 Remote Poll screen, if there are multiple instances of the screen, they will share the same Target Address. This may happen if there are multiple Telnet sessions, or a serial port session and a Telnet session. The last address entered is the address that will be polled.

7 On the VT100 Remote Poll screen, if an IP address is entered but the stack has no IP configuration, no error message is displayed. A similar problem will occur with IPX.

8 On the VT100 Change User screen, if the values entered in the `New Password' and `Confirm Password' fields are different, an error message is displayed when `OK' is selected. If [Return] is then pressed, a null password is set for the user. The user can log in, but if an attempt is made to change the password again, the message `Old Password Field Not Completed' will be displayed.

9 If the stack has a configuration that results in a large number of traps being generated within a short space of time, it is possible that some traps will not be sent.

10 If the Software Upgrade (System Loader) download activity fails, the trap reporting the error may indicate an incorrect status. Successful download will always result in a correct trap status.

11 When downloading a new agent image, if there is a sustained background level of broadcast traffic on the network, this may increase the download time. On a lightly loaded network, the download should take approximately 5 minutes. If the download has not completed within 10 minutes, we recommend that you reset the module and retry when the network load is lighter. The System Configuration Utility must then be used to effect the download, as no agent image will exist on the Bridge/Management Module at this time.

12 `% Broadcast Frame Bandwidth' calculates the bandwidth of broadcast frames based on the frame count and not octet count. The `% Received Bandwidth' is based on an octet count. If only broadcast traffic is present on the network, the

`% Broadcast Frame Bandwidth' will show a lower value than `% Received Bandwidth'.

13 If the `Maximum Age Timer', `Hello Timer' or `Forward Delay Timer' for Spanning Tree are changed, they will not come into effect until Spanning Tree is turned from off to on, or the Bridge/Management Module is reset.

14 The Remote Poll Time may give a value greater than it actually is.

15 If resilient link pairs are set up, on power-up two identical

`ResilientStateChange' traps are generated.

16 If a resilient pair is set up, and the unit containing either of the ports is removed from the stack and is replaced by a coaxial unit (which does not support resilience), the resilient link pair cannot be deleted.

17 On the Bridge Statistics screen, `Frames Transmitted' may be zero, but Octets Transmitted may not be zero. This is because Frames Transmitted are forwarded frames that are transmitted, whilst 'Octets Transmitted' includes management octets transmitted.

18 The `Autopartition Count' does not count correctly when the source of the partition is the Transceiver Module.

19 Descriptions in the mrmBasicCardPackage section of the MIB refer to MSH and ECS products whereas references should be the the FMS II Bridge.

20 In a Spanning Tree configuration we recommend that the port priority of the bridge is not changed, as in some configurations this may cause a loop.

21 In a Spanning Tree configuration with the Internal Bridge Port connected to the External Bridge Port and with broadcast traffic on the network, the following problem could arise:

22 If one of the bridge ports is disconnected, Spanning Tree will reconfigure the network. If subsequently it is reconnected a loop may be formed with both bridge ports forwarding.

23 This product is optimized for applications where traffic is largely to the workgroup (a self-contained group of servers and workstations).

Building Ethernet networks using bridging can be subject to limitations under certain conditions. Here are some examples:

Broadcast Storms - These occur when rogue devices send broadcast packets which elicit responses from every device on the network, leading to reduced network performance. Bridges generally forward all broadcast packets and so such problems can be propagated throughout the network.

Multicast Storms - These are similar to broadcast storms, but are caused by multicast packets (packets addresses to groups of devices). These will be rarer than broadcast storms.

Packet Loss - Bridges can drop packets for a variety of reasons. This may lead to reduced performance for traffic being forwarded through the bridge.

Should any of the above symptoms be observed, please contact your supplier to discuss ways of optimizing your network design.

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