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
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