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Cisco Ethernet Switch Module (ESM) Telnet session via the management module may pause or disconnect - IBM BladeCenter

Troubleshooting


Problem

Cisco switch Telnet session via the management module may pause or disconnect - IBM BladeCenters

Resolving The Problem

Source
 
RETAIN tip: H183786

Symptom

A Telnet session to the Cisco Ethernet Switch Module (ESM) via the Management Module (MM) link on VLAN 1 may pause or be disconnected whenever an ESM configuration change activates a spanning tree re-calculation using the Spanning Tree Protocol (STP). The Telnet session will continue or can be reconnected after a brief delay while the STP activity completes.
 
Affected configurations

The system may be any of the following IBM BladeCenters:

  • IBM BladeCenter, type 8677, any model
  • IBM BladeCenter HS40, type 8839, any model
  • IBM BladeCenter HS20, type 8678, any model
  • IBM BladeCenter HS20, type 8832, any model
  • IBM BladeCenter JS20, type 8842, any model
  • IBM BladeCenter T, type 8730, any model
  • IBM BladeCenter T, type 8720, any model

The system is configured with any diagnostics.
 
The system's diagnostics pass.

The BIOS levels affected are:

  • All
Solution

None. The system is working as designed.

Workaround

The Telnet interruption can be minimized by removing the management VLAN, VLAN 1, from the external ports. VLAN 1 is included in the external ports by default to support in-band management of the switch. Removing VLAN 1 may be acceptable to users who prefers out of band management of the ESM.

Additional information

STP is enabled on the Cisco MM links by design. This behavior is viewed as an inconvenience. The interruption of the MM link is a normal possibility for a link with spanning tree enabled. With the reason for the interruption understood, it is easy to reconnect the telnet session after the STP activity has completed.

Document Location

Worldwide

Operating System

BladeCenter:Operating system independent / None

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Document Information

Modified date:
29 January 2019

UID

ibm1MIGR-59092

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