[mrtg] Re: MRTG Mapping Fractional T1

Andrew Hull list at racc2000.com
Thu Oct 13 17:27:18 MEST 2005

I see a potential problem:

the 'bandwidth 1024' statement in your interface config tells me that 
your provider is selling your a T1 throttled to 1024 kilobit/sec.

The 'bandwidth' statement instructs the interface not to exceed 1024 
kbit/sec, this is good. I'm guessing that your provider has limited the 
number of timeslots (channels) that the circuit uses, but your interface 
is currently configured to use all of them (the default).

You can confirm that with "show service-module serial1"
You'll see a line in the output like:

Fraction has 24 timeslots (64 Kbits/sec each), Net bandwidth is 1536 

The interfaces on each end of the circuit need to match, and I'm 
guessing that your provider has the circuit limited to 16 timeslots. It 
would be worth a call to your provider to confirm this.

16 * 64kbps == 1024 kbps

Adding "service-module t1 timeslots 1-16" would limit your interface to 
16 timeslots and (hopefully) fix your problems.

Also, I didn't see a clock source statement in your interface config. It 
would be a good idea to add one. Your provider is probably providing the 
timing for the circuit (another good thing to confirm) so adding 
"service-module t1 clock source line" to the interface would do it.

Hope that helps,
Andrew Hull

Natalie Aloi wrote:
> Andrew, - I think maybe that is part of my problem incorrectly
> configured channelized t1 (the reason I want to monitor all channels -
> is I have complaints of throughput and or latency and MAYBE one of the
> channels is not accepting traffic) however this is the config from my
> router.
> interface Serial1
>  description To SynergyHQ int s1/1
>  bandwidth 1024
>  ip address
>  ip access-group 102 in
>  no ip redirects
>  no ip unreachables
>  no ip directed-broadcast
>  no ip proxy-arp
>  no cdp enable

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