[j-nsp] Default Delay Buffer On Channelized T3

[Matt Bentley]

*Hi Experts:*
*
*
*I've been reading the following doc, and am having a hard time figuring it
out.*
*
*
http://www.juniper.net/techpubs/software/junos/junos93/swconfig-cos/configuring-large-delay-buffers-for-slower-interfaces.html
*
*
*I have the following config on a channelized T3 (note that
q-pic-large-buffer IS enabled for the PIC).*

set chassis fpc 0 pic 1 q-pic-large-buffer large-scale
set interfaces t3-0/2/0:4 mtu 1504
set interfaces t3-0/2/0:4 clocking internal
set interfaces t3-0/2/0:4 encapsulation ppp
set interfaces t3-0/2/0:4 t3-options compatibility-mode digital-link
subrate 44.2Mb
set interfaces t3-0/2/0:4 t3-options payload-scrambler
set interfaces t3-0/2/0:4 unit 0 family inet address x.x.x.x/x
set class-of-service interfaces t3-0/2/0:4 scheduler-map SCHEDULER_MAP
set class-of-service scheduler-maps SCHEDULER_MAP forwarding-class
best-effort scheduler BEST_EFFORT
set class-of-service scheduler-maps SCHEDULER_MAP forwarding-class
assured-forwarding scheduler ASSURED_FORWARDING
set class-of-service scheduler-maps SCHEDULER_MAP forwarding-class
expedited-forwarding scheduler EXPEDITED_FORWARDING
set class-of-service scheduler-maps SCHEDULER_MAP forwarding-class
network-control scheduler NETWORK_CONTROL
set class-of-service schedulers EXPEDITED_FORWARDING transmit-rate percent
10
set class-of-service schedulers EXPEDITED_FORWARDING buffer-size percent 10
set class-of-service schedulers EXPEDITED_FORWARDING priority high
set class-of-service schedulers ASSURED_FORWARDING transmit-rate percent 10
set class-of-service schedulers ASSURED_FORWARDING buffer-size percent 10
set class-of-service schedulers ASSURED_FORWARDING priority low
set class-of-service schedulers NETWORK_CONTROL transmit-rate percent 5
set class-of-service schedulers NETWORK_CONTROL buffer-size percent 5
set class-of-service schedulers NETWORK_CONTROL priority low
set class-of-service schedulers BEST_EFFORT transmit-rate remainder
set class-of-service schedulers BEST_EFFORT buffer-size remainder
set class-of-service schedulers BEST_EFFORT priority low


*Juniper says:*

When you include the q-pic-large-buffer statement in the configuration, the
larger buffer is transparently available for allocation to scheduler
queues. The larger buffer maximum varies by interface type, as shown in Table
31<http://www.juniper.net/techpubs/software/junos/junos93/swconfig-cos/configuring-large-delay-buffers-for-slower-interfaces.html#id-11188734>
.
With Large Buffer Sizes Enabled

Channelized T3 and channelized OC3 DLCIs—Maximum sizes vary by shaping rate:

With shaping rate from 64,000 through 255,999 bps

4,000,000 microseconds

With shaping rate from 256,000 through 511,999 bps

2,000,000 microseconds

With shaping rate from 512,000 through 1,023,999 bps

1,000,000 microseconds

With shaping rate from 1,024,000 through 2,048,000 bps

500,000 microseconds

With shaping rate from 2,048,001 bps through 10 Mbps

400,000 microseconds

With shaping rate from 10,000,001 bps through 20 Mbps

300,000 microseconds

With shaping rate from 20,000,001 bps through 30 Mbps

200,000 microseconds

With shaping rate from 30,000,001 bps through 40 Mbps

150,000 microseconds

With shaping rate up to 40,000,001 bps and above

100,000 microseconds

*So, my shaping rate is greater than 40Mbps, so it looks like the maximum
delay buffer for me is 100,000 microseconds.*
*
*
*My questions:*
*1.  Is the 100,000 microseconds a limit per scheduler, or for the entire
interface.  For example, if I allocate 100,000 microseconds temporal buffer
to BE, is nothing left for anything else?*
*2.  It sounds like the 100,000 is the max you CAN configure.  What is the
default delay buffer if you only configure the scheduler above? *
*3.  Does having "remainder" affect the delay buffer calculation?  I'm
assuming it would, just not sure how.*
*4.  Is there any way I can see what the actual delay buffer setting is on
a given scheduler for a given interface?*
*5.  If I increase it to the maximum, will doing so affect other
channelized T3s on the same PIC?  Am I pulling from one of them when I
configure a larger value?*
*
*
*Hopefully this makes sense.*
*
*
*Thanks!*
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