Replacing Or Adding A Stack Unit - Nortel 4500 Series Installation Manual

48 Installing the Nortel Ethernet Routing Switch
Redundant cascade stacking
1. Base Unit
2. Last Unit
3. Unit selector switch
4. Cascade Cable
In the example, the following occur:
•
•
•
•

Replacing or adding a stack unit

To replace a failed stack unit or insert a new unit into a stack, perform
this procedure.
Copyright © 2007, Nortel Networks
.
Unit 3 becomes non-operational due to a unit failure, cable
disconnection, or a loss of power.
Units 2 and 4, directly upstream and downstream from Unit 3, sense
the loss of link signals from unit 3. The software directs all the data to
traverse the remaining path.
The Cascade Down LED for Unit 2 and the Cascade Up LED for Unit
4 turn amber to indicate an error.
The remaining stack units remain connected and continue to operate.
Note: Automatic Unit Replacment (AUR) for both configuration and
software is enabled for all Nortel Ethernet Routing Switch 4500 Series
platforms and software releases. This means that the agent code image,
on a replacement unit, is automatically upgraded or downgraded to
Nortel Ethernet Routing Switch 4500 Series
Installation Guide
NN47205-300 02.01 Standard
5.0 23 February 2007
Nortel Networks Confidential