Nortel Ethernet Routing Switch 4500 series stacking 59• The Cascade Down LED for Unit 2 and the Cascade Up LED for Unit4 turn amber to indicate an error.• The remaining stack units remain connected and continue to operate.Replacing or adding a stack unitTo replace a failed stack unit or insert a new unit into a stack, performthis procedure.ATTENTIONAutomatic Unit Replacement (AUR) for both configuration and software is enabledfor all Nortel Ethernet Routing Switch 4500 Series platforms and softwarereleases. This means that the agent code image, on a replacement unit, isautomatically upgraded or downgraded to match the software running on thestack. In addition, when a like-for-like replacement of a failed unit occurs, anyport-specific configuration is restored .Step Action1 Remove the failed switch from the stack.2 Obtain a like-for-like replacement switch.3 With the new unit powered off, physically insert the new unit in thestack and reconnect the stack cables.4 Turn on the new unit.Depending on the software load on the replacement switch, it mayautomatically reboot one or two times before joining the stack as afully operational member.5 Check the log file on the stack to ensure that the replacement unitcorrectly joined the stack. The log file displays AUR informationmessages.—End—If the base unit is being replaced, remember that the stack has electeda temporary base unit and the new unit does not automatically assumethe base unit status. Configure the new unit as the base unit, using theUnit Select switch, and reset the Unit Select switches of the other stackmembers to non-base units.Nortel Ethernet Routing Switch 4500 SeriesInstallation GuideNN47205-300 (322811-B) 03.01 Standard5.1 19 November 2007Copyright © 2007, Nortel Networks.
