flex codec complexity

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Mar 27th, 2007
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This is from Cisco link about the codec complexity. I am assuming flex is the default. Then I shouldn't be able to use G729 for the dial-peer 1 voip, right? Since flex only support g711. Thanks

High complexity:G.711 a-law and mu-law; G.726 @ 32k, 24k, and 16k; G.729, A, B and AB; G.723.1 @ 5.3k and 6.3k; G.728, GSMFR, GSMEFR, clear channel codec, and fax relay

Medium complexity G.711 a-law and mu-law; G.726 @ 32k, 24k, and 16k; G.729A and AB; clear channel codec, and fax relay

Flexible or low complexity G.711 a-law and mu-law

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Overall Rating: 5 (3 ratings)
gogasca Tue, 03/27/2007 - 23:07
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Hi ciscoforum,

Flex mode, available only on hardware platforms that use the C5510 chipset, eliminates the requirement to specify the codec complexity at configuration time. A DSP in flex mode accepts a call of any supported codec type, as long as it has available processing power. The overhead of each call is tracked dynamically via a calculation of processing power in millions of instructions per second (MIPS). Cisco IOS performs a MIPS calculation for each call received and subtracts MIPS credits from its budget whenever a new call is initiated.

At 15 MIPS per call:

?G.711 (a-law, mu-law)

?Fax/modem pass-through

?Clear channel

At 30 MIPS per call:

?G.726 (32K, 24K, 16K)


?Fax relay


?G.729 (a, b, ab)

At 40 MIPS per call:


?G.723.1 (32K, 24K, 16K)

?G.723.1a (5.3K, 6.3K)


?Modem relay

For example, each DSP has a budget of 240 MIPS, for a total budget of 720 MIPS per NM-HD-2VE module. For an NM-HDV2 module, the budget per DSP is also 240 MIPS, but refer to Table 6-2 to determine the total number of MIPS available based on your choice and the number of PVDMs.

Compared to medium or high complexity mode, flex mode has the advantage of supporting the most G.711 calls per DSP. In medium complexity mode a DSP can support 8 G.711 calls, while flex mode supports 16 G.711 calls

paolo bevilacqua Wed, 03/28/2007 - 04:08
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Great info, thanks!


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