[cisco-voip] increasing Maximum Serving Count TFTP service parameter

[Wes Sisk]

A few things come to mind -
you can use BAT to reset phones at a slower rate in smaller groups. just 
tick the box to reset the phones.  BAT changes are throttled so phones 
will have a better chance at success.

There is a TFTP perfmon counter that indicates when serving count has 
been exceeded.  If that incremented then increasing serving count may be 
beneficial. If that didn't increment then the problem lies elsewhere.

I don't see a CM version indicated here.  I also don't see indication of 
what other activities may have been going on when the reset was 
attempted.  Activities like updating device pools or CM groups cause 
TFTP to rebuild all files.  Rebuilding files can be slow. It is slowed 
further if this is pre-6.x where all database reads go to the publisher 
and the publisher is located across a WAN.  Informix reads over WAN are 
particularly painful.  Windows versions had a TFTP service parameter to 
"write TFTP files to disk" which further slowed TFTP rebuilds.  TFTP 
requests while TFTP is rebuilding cause "processing allocation exceeded" 
(text may be different, memory is a bit fuzzy) which increments the same 
perfmon counter mentioned above.

If the phones are over a WAN from the TFTP server this is also 
exacerbated.  TFTP over wan is slow causing transfer to take longer 
which keeps each thread busy longer which causes more processing 
allocation exceeded.  Best bet in this scenario is controlled reset of 
phones, see the BAT approach above.

Digging even deeper TFTP transactions fail more frequently when there is 
a speed/duplex mismatch between the TFTP server and the connected 
switch. Ironically this too manifests more often when phones are over a 
WAN away from the TFTP server.

If the TFTP server is not also running call processing then increasing 
thread count should be safe.

Regards,
Wes

On 3/29/2011 5:02 PM, Lelio Fulgenzi wrote:
> I'm trying to upgrade about 4000 7940s and this morning's first 
> attempt didn't pan out so well.
>
> After two resets, only 850 of them upgraded.
>
> I am resetting all phones from the device defaults page. I don't have 
> any other way to reset b/c device pools contain other phone models.
>
> Any advantage to increasing the Maximum Serving Count TFTP service 
> parameter? It's currently set to 1000, but it says I can increase this 
> to 5000.
>
> We have advanced server running on our dedicated TFTP server. 
> Properties shows Pentium III 1266MHz with 2GB RAM.
>
> thoughts?
>
> ------------------------------------------------------------------------
> This parameter specifies the maximum number of client requests to 
> accept and to serve files at a time. Specify a low value if you are 
> serving files over a low bandwidth connection. You can set it to a 
> higher number if you are serving small files over a large bandwidth 
> connection and when CPU resources are available, such as when no other 
> services run on the TFTP server. Use the default value if the TFTP 
> service is run along with other Cisco CallManager services on the same 
> server. Use the following suggested values for a dedicated TFTP 
> server: 1500 for a single-processor system and 3000 for a 
> dual-processor system. If the dual-processor system is running Windows 
> 2000 Advanced Server, the serving count can be up to 5000.
> This is a required field.
> Default: 200.
> Minimum: 1.
> Maximum: 5000.
> ------------------------------------------------------------------------
>
> ---
> Lelio Fulgenzi, B.A.
> Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Cooking with unix is easy. You just sed it and forget it.
>                               - LFJ (with apologies to Mr. Popeil)
>
>
>
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