There was a discussion not long ago about the differences between native and hybrid modes on a Cat6k. The following passages are from a white paper I found on CCO, posted 9/5/2001. The interesting part is where it mentions the IOS must reset all linecards in the chassis for a successful failover from a failed sup. engine. A strong case, I think, to run CatOS on the switch...
BTW - Passed the written Saturday. I used the same books everybody else did, so nothing new I can add about my "experience". ;-} Q. Which network-level resiliency options does the Catalyst 6000 family support? A. For network-level resilience, Catalyst 6000 family switches also support automatic recovery from failure using spanning tree per VLAN, and support load sharing for faster link convergence using Cisco Fast EtherChannel or Gigabit EtherChannel technologies. Load balancing with even higher availability can also be accommodated using Cisco multimodule channeling, where ports from different line cards can be aggregated into higher-bandwidth links. Catalyst 6000 family switches are also capable of load balancing across Layer 3 paths. For maximum availability, the Catalyst 6000 family switches support Hot Standby Router Protocol (HSRP), providing fast cutover to a backup system in the event of a catastrophic failure. HSRP is available between a pair of MSFC engines in the same chassis (Catalyst OS), between two MSFC engines in different chassis, and between an MSFC and an external router. (Caveats in Cisco IOS software for the Catalyst 6000 family of switches are listed later in the document.) It is important to note that the Catalyst OS and Cisco IOS software for the Catalyst 6000 family of switches images differ with respect to their high-availability mechanisms. The Cisco IOS software for the Catalyst 6000 family of switches supports high-availability functionality via a model akin to that of the Catalyst 7500 series routers enhanced high system availability (EHSA). Meaning that for a supervisor recovery, the standby supervisor must first reset all line cards; in this case, a recovery will take from 30 to 60+ seconds (configuration dependent). In addition, because of the EHSA model being employed, the MSFCs are not configured independently of one another when in a redundant configuration, meaning that currently redundant MSFCs in a system running Cisco IOS software for the Catalyst 6000 family of switches cannot employ HSRP between the MSFCs. The primary MSFC, however, can run HSRP with an external router, and the standby MSFC will become primary in the event of a failure (please refer to previous statement with respect to supervisor recovery). -- Rik Guyler Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=21713&t=21713 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
