OTBF 1 - (32) - 127: Size of output buffer for DCH

[GHTROUT]

I'm curious if some folks managing rather large switches have tweaked the OBTF Value in the ADAN DCH.

If you did something other than defaults, how did you determine what value was best.

Also - did you apply the value to _all_ DCHs or just specific ones.

This parameter configures how many output buffers are allocated for DCH messages outgoing from the system CP to the D-channel handling card. The more that are created, the deeper the buffering. For systems with extensive D-channel messaging, such as call centers using NACD, the parameter should be set at 127. For other systems with moderate levels of D-channel messaging, OTBF should be set at the smaller of the following two quantities: Total B-channels – (30 × MSDL cards with D-channels) or 127.

For example, if a system in a standard office environment is configured with 7 T1 spans, 2 D-channels located on two different NTBK51 daughterboards, and 2 back-up D-channels, the total number of B-channels is (7 × 24) – 4 = 164. Configure OTBF to be the smaller of 164 – (30 × 2) = 104 and 127 which is 104.

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[tnphoneman]

I always set mine for 127 and have been for years. Just like changing LFAC and BIPC in the DDB to 0.

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[GHTROUT]

That was extremely valuable info. Thanks again. I've never paid much attention to LFAC and BIPC until now.


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[tnphoneman]

It sure helps the T1 recover on it's own. Any switch I have been logged into that has been changed. I don't want the 2 am call for a T1 that would have recovered on it's own.

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[GHTROUT]

Yes! Guess who was on-call last night I will remember those pointers forever.


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[tnphoneman]

glad to help

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[PERRYPJ]

Excuse my ignorance but I have looked through the Install and the Maintence PDF and I can find no reference to OTBF, what is the purpose of this buffer.

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[GHTROUT]

Look in the Maintenance Input/Output guide - LD 73

good info


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[tnphoneman]

OTBF is in the Dchannel programming

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[PERRYPJ]

Yes I know but what does it do, there nothing in LD 73 on it. The only place is in LD 17

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[GHTROUT]

Ooops, sorry...was getting what prompt you wanted mixed up.

I found the quoted text (see start of thread) in the book called "ISDN Primary Rate Interface Maintenance"


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