Datasheet

CSUF uses the GigaStack GBIC and runs on all Catalyst 3550 switches, all Catalyst 3500 XL
switches, Catalyst 2950 switches with GBIC module slots, and only on modular Catalyst 2900 XL
switches that have the 1000BASE−X module installed.
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Up to nine stack switches can be connected through their stack ports to the multidrop backbone. Only
one stack port per switch is supported.
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Each stack switch can be connected to the spanning−tree backbone through one uplink.•
If the stack consists of a mixture of Catalyst 3550, Catalyst 3500 XL, Catalyst 2950, and Catalyst
2900 XL switches, up to 64 VLANs with spanning tree enabled are supported. If the stack consists of
only Catalyst 3550 switches, up to 128 VLANs with spanning tree enabled are supported.
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The CSUF feature is supported only when the switch is running PVST .•
If a stack that has Catalyst 2955, Catalyst 2950, or Catalyst 2940 switches also has Catalyst 2900 XL
or Catalyst 3500 XL switches, cross−stack UplinkFast (CSUF) does not function if the management
VLAN on the Catalyst 2900 XL or Catalyst 3500 XL switches is changed to a VLAN other than
VLAN 1 (the default). The workaround is to make sure that the management VLANs of all Catalyst
2900 XL or 3500 XL switches in the stack are set to VLAN 1. (CSCdv82224)
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Troubleshooting
The following are troubleshooting steps to take on a case by case scenario:
For common problems and their solutions, refer to the following document:
Common Problems and Their Solutions
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For an explanation of GigaStack LEDS, refer to the following document:
GigaStack GBIC LEDs
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Error Message: NO_LOOP_DETECT
NO_LOOP_DETECT, GIGASTACK, LOG_ALERT, 0, The link neighbor of link %d of GigaStack
This error message indicates that there is no acknowledgment for GigaStack loop detection request received
from one of the links on a GigaStack GBIC. Either the neighboring switch does not support the GigaStack
loop breaking algorithm, or the link between the two GigaStack GBICs is broken. Under this condition, a
GigaStack loop topology is not be automatically detected, and the connectivity between switches in the stack
could be lost.
If loop topology is used in the GigaStack, make sure the latest software is running on all switches in the stack.
Check the GigaStack GBICs involved to make sure they are functioning.
If no loop exists in the GigaStack GBIC stack, as a workaround, you can disable the loop−breaking algorithm
by issuing the no gigastack loop−breaking [interface−id] global configuration command. This is meant as a
workaround until you can upgrade all switches to support loop breaking.
One Way Traffic Flow
When using the GigaStack GBIC with a Catalyst 3500 XL switch or 2900 XL modular switch and IOS
Release 11.2(8.1)SA6, you may experience a problem with traffic flow in one direction when you insert or
remove a cable. This is resolved in 11.2(8.2) SA6 and greater.
Link Flaps and Never Stabilizes
Cisco − Catalyst Switch GigaStack Configuration and Implications