At 8:02 PM +0000 7/13/03, annlee wrote: >N+1 means one more than that required. Suppose you have a large switch which >can operate half the blade capacity with one power supply and it requires 2 >power supplies to operate fully populated. Then, when it is half-populated, >dual power supplies provides N+1, because it has one more than the >requirement. When fully populated, it has N+1 if it has 3 power supplies in >place and available. > >This is the kind of HA requirement typically demanded by telcos and others >for whom off-line is simply not an option. > >HTH > >Annlee
Indeed, there are HA techniques, more applicable to communications channels, that may offer more or less resources than N+1. I have seen nuclear war command and control systems that would send out a launch message on up to 23 different media. 1+1 actively transmits the same data on two links, usually accepting the first copy that has a correct error check sequence and discarding the other. Probably the most common application is SSCOP, the data link protocol for SS7 and Q.2931. 1:1 only one active link, but a dedicated standby link (think FDDI) M:N N backups for M active resources. > >""Lo Ching"" wrote in message >news:[EMAIL PROTECTED] >> Dear All, >> >> What's the meaning of N+1 redundancy? I found a chassis switch with 4 >power >> supply and it states N+1 power redundancy. >> >> Thanks. >> >> rgds, >> Lo Ching Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=72219&t=72202 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]