Re: Interesting FRTS Behavior Driving Me Mad

Hey Michael, thanks for your reply. I believe you found the magic ratio I
was searching for. I didn't think to look at the byte-count. Excellent!!!
At least now we know why. Sort of like how I also found a few months ago
the highest possible value you can make the Tc is 249ms even though some
docs say it maxes out at 125ms.

This makes perfect sense now based on the byte count limit of 10000 bytes /
interval.

80007 bits / 8 = 10000.875 Bytes = 10000 Bytes rounded down
80008 bits / 8 = 10001 Bytes exactly

Nicely done sir!

On Mon, Nov 30, 2009 at 4:00 AM, Michael McFarlin <router.genie_at_gmail.com>wrote:

> Joe
>
> That's an interesting observation. I've never noticed this behavior before
> either. It looks like the maximum byte-limit is 10000. I'm guessing that
> when you give a Bc value that forces the byte-limit to over 10000 per
> interval, it recalculates the Bc as well as the Tc. I wonder what purpose
> this serves.
>
> --Here are the values I used in the map class
>
> map-class frame-relay FRTS
> frame-relay cir 1000000
> frame-relay bc 125000
>
>
> R2# sh traffic-shape
>
> Interface Se1/0
>
> Access Target Byte Sustain Excess Interval Increment
> Adapt
> VC List Rate Limit bits/int bits/int (ms) (bytes)
> Active
>
> Interface Se1/0.23
>
> Access Target Byte Sustain Excess Interval Increment
> Adapt
> VC List Rate Limit bits/int bits/int (ms) (bytes)
> Active
> 203 1000000 7875 125000 0 63 7875 -
>
> Notice that 7875*8 = 63000bits
>
>
> -Mike McFarlin
> router.genie_at_gmail.com
>
>
>
> On Mon, Nov 30, 2009 at 12:07 AM, Joe Astorino <jastorino_at_ipexpert.com>wrote:
>
>> Oh yeah and the essential: two different IOS , two different platforms...
>>
>> R2(config-map-class)#do sh ver | i 12.4
>> Cisco IOS Software, 3800 Software (C3825-ADVENTERPRISEK9-M), Version
>> 12.4(24)T1, RELEASE SOFTWARE (fc3)
>>
>>
>> R5(config-if)#do sh ver | i 12.4
>> Cisco IOS Software, 3600 Software (C3640-JK9O3S-M), Version 12.4(13a),
>> RELEASE SOFTWARE (fc1)
>>
>>
>>
>>
>> On Mon, Nov 30, 2009 at 3:02 AM, Joe Astorino <jastorino_at_ipexpert.com
>> >wrote:
>>
>> > Has anybody seen anything like this before? It seems the formula for
>> how
>> > my router is calculating Tc dynamically changes based on the given value
>> of
>> > Bc which I have not read about in any book or cisco doc as of yet.
>> >
>> >
>> > R2(config-map-class)#do sh run int s0/1/0 | i frame-relay
>> > encapsulation frame-relay
>> > frame-relay class foo
>> > frame-relay traffic-shaping
>> > frame-relay map ip 100.100.100.5 205 broadcast
>> > no frame-relay inverse-arp
>> >
>> > R2(config-map-class)#do sh run | beg map-class
>> > map-class frame-relay foo
>> > frame-relay cir 768000
>> > frame-relay bc 80007
>> >
>> > With this setup, I expect the long standing formula Tc = Bc / CIR to
>> hold
>> > true. Therefore Tc should be equal to 80007 / 768000 = 0.10417578125
>> > seconds = 104ms rounded down and indeed it is
>> >
>> > R2(config-map-class)#do sh traffic
>> >
>> > Interface Se0/1/0
>> > Access Target Byte Sustain Excess Interval Increment
>> > Adapt
>> > VC List Rate Limit bits/int bits/int (ms) (bytes)
>> > Active
>> > 205 768000 10000 80007 0 104 9984 -
>> >
>> >
>> > However, as soon as I cross the Bc boundary of 80007 and set it to 80008
>> my
>> > Tc is changed to what appears to be (Bc / CIR) / 2 !!! WTF?
>> >
>> > R2(config-map-class)#do sh traffic
>> >
>> > Interface Se0/1/0
>> > Access Target Byte Sustain Excess Interval Increment
>> > Adapt
>> > VC List Rate Limit bits/int bits/int (ms) (bytes)
>> > Active
>> > 205 768000 5000 80008 0 52 4992 -
>> >
>> > As you can see the Tc has been set to 52 ms which just so happens to be
>> 1/2
>> > of the previous value of 104ms. Any clues?
>> >
>> >
>> >
>> >
>> >
>> > --
>> > Regards,
>> >
>> > Joe Astorino CCIE #24347 (R&S)
>> > Sr. Technical Instructor - IPexpert
>> > Mailto: jastorino_at_ipexpert.com
>> > Telephone: +1.810.326.1444
>> > Live Assistance, Please visit: www.ipexpert.com/chat
>> > eFax: +1.810.454.0130
>> >
>> > IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA
>> (R&S,
>> > Voice & Security), CCNP, CCVP, CCSP and CCIE (R&S, Voice, Security &
>> Service
>> > Provider) Certification Training with locations throughout the United
>> > States, Europe and Australia. Be sure to check out our online
>> communities at
>> > www.ipexpert.com/communities and our public website at www.ipexpert.com
>> >
>> >
>> >
>>
>>
>> --
>> Regards,
>>
>> Joe Astorino CCIE #24347 (R&S)
>> Sr. Technical Instructor - IPexpert
>> Mailto: jastorino_at_ipexpert.com
>> Telephone: +1.810.326.1444
>> Live Assistance, Please visit: www.ipexpert.com/chat
>> eFax: +1.810.454.0130
>>
>> IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA
>> (R&S,
>> Voice & Security), CCNP, CCVP, CCSP and CCIE (R&S, Voice, Security &
>> Service
>> Provider) Certification Training with locations throughout the United
>> States, Europe and Australia. Be sure to check out our online communities
>> at
>> www.ipexpert.com/communities and our public website at www.ipexpert.com
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>>
>>
>>
>>
>>
>>
>>
>
>
> --
> Mike McFarlin
> router.genie_at_gmail.com
>

-- 
Regards,
Joe Astorino CCIE #24347 (R&S)
Sr. Technical Instructor - IPexpert
Mailto: jastorino_at_ipexpert.com
Telephone: +1.810.326.1444
Live Assistance, Please visit: www.ipexpert.com/chat
eFax: +1.810.454.0130
IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA (R&S,
Voice & Security), CCNP, CCVP, CCSP and CCIE (R&S, Voice, Security & Service
Provider) Certification Training with locations throughout the United
States, Europe and Australia. Be sure to check out our online communities at
www.ipexpert.com/communities and our public website at www.ipexpert.com
Blogs and organic groups at http://www.ccie.net