CIR triangle forumla for QoS calculations

Supposedly an easy way to remember equations in physics and maths, is only really useful at low levels.

It works like this – if I want to remember how to use the formula for density, Density = Mass / Volume , I’d put it into a triangle like so –

/ M
/ D * V

Now, if I want the formula for Density, I just cover up the D with my finger, and all that’s left is the M/V bit. That’s my equation. The same works for working out all the letters.

The idea is that you just remember the order of letters in the triangle rather than the equation. Not that much use, though.

Tc = Bc/CIR (in seconds) is the formula.

The router internally calculates the value of Tc based on the configured CIR and Bc values.

If Bc/CIR is more than or equal to 125 ms, it uses an internal Tc value if the router determines that traffic flow will be more stable with a smaller interval.
You can use the show traffic-shape command to determine whether your router is using an internal value for Tc or the value that you configured.

In your example with CIR of 64K and Bc of 8000K, (8,000/64,000) = 0.125 or 125ms. If we wanted a Tc of 100ms, we would simply configure the Bc to be 6400. Then using the formula Tc=Bc/CIR it would be 6,400/64,000 = .1 or 100ms.

Best wishes,


EEM event manager – use cron timer

event manager applet PHONE_POWER_OFF
event timer cron name PHONE_POWER_OFF cron-entry “0 11 * * 1-5”
action 1.0 cli command “enable”
action 1.1 cli command “conf t”
action 1.2 cli command “interface f0/23”
action 1.3 cli command “power inline never”
action 1.4 syslog msg “PHONE_POWER_OFF by EEM script”
event manager applet PHONE_POWER_ON
event timer cron name PHONE_POWER_ON cron-entry “0 8 * * 1-5”
action 1.0 cli command “enable”
action 1.1 cli command “conf t”
action 1.2 cli command “interface f0/23”
action 1.3 cli command “no power inline never”
action 1.4 syslog msg “PHONE_POWER_ON by EEM script”



Conference Bridge – Handles Conference Calls
-CUCM software: G.711 only
-Hardware DSP(digital signal processor):
Mutlti-codec (G.711 G.729) on router modules NM-HD-2VE

Media Termination Point – Hold calls on Hold
-Hold, Transfer, Conference, etc…

Annunciator – Plays Recorded Annoucements

Transcoder – Converts one codec to another, CUCM CANNOT DO THIS FUNCTION, need

DSCP hardware, only needed in case when phone needs to send with one codec and

the device on the other end does a different codec, not in the case of any

phone to phone when they negotiate codec to use

MoH Server – Plays Music on Hold

CUCM Services for Media Resources:
Cisco IP Voice Media Streaming App
Cisco MoH Audio Translator – converts mp3 and wav to codec for MoH

Resource Manager(assinged to Devices)
MRGL(list of groups)
MRG(groups of resources, example Software, Hardware)
Resource(Transcoder,MoH, Conference Bridge, DSPs)

Partitions and CSS Best Practices

Partitions and CSS Best Practices

1. Implement PSTN calling restrictions
– Create partition with ALL diabale numbers
– Create partition with BLOCKED numbers
– In the CSS put the BLOCKED partition before the other

partitions that allow access or are ‘dialable’, like ACL top

down order of processing


The ! says the next digit dialed activates dialing

9.[2-9]XXXXXX (local numbers dialed)
9.1[2-9]XX[2-9]XXXXXX (long distance)
9.011! (International numbers dialed)


2. CSS can be applied to a LINE and a DEVICE


Results into one merged or CONCATENATE into one CSS with the

LINE being checked first and the DEVICE second:

***RESTRICTIONS should be applied to the LINE***

3. Use Partitions/CSS for Emergency Call Routing

Example two offices one in Dallas one in Little Rock
Create Partition for Dallas_911 and one for Little_Rock_911
Create Route Pattern for Dallas_911:
route calls to local Dallas PSTN(gateway router)

Create Route Pattern for Little_Rock_911
route calls to local Little Rock PSTN(gateway router)

Create CSS Dallas_CSS

Create Css Little_Rock_911

So then Dallas office cannot access Little Rock Partions/CSS

for 911

4. Never use the [none] Partition or CSS
this exisits in every CSS at the bottom implicit [none] like

implicit deny any any in ACL

[NONE] CSS can only reach the [NONE] Partition

5. Do Not forget the Gateways and Call Forward settings are

set to the [none] Calling Search Space (CSS)

6. Use calling restrictions to cause Auto-Registered phones

to act as PLAR devices (Private Line Automatic Ringdown) or

BAT phone direct dial line… Then when someone will pickup

the phone and ring to Help Desk phone for support…

Create Partition AUTO_PT with translation pattern empty

translation pattern field, with Called Party Transformation

Mask of Help Desk number (2001), then Create AUTO_CSS with

only the AUTO_PT…

When someone picks up the new auto registred phone no digits

dialed it rings down or PLAR…

Under new Device Pool add AUTO_DP with CSS for

Auto-registration assign AUTO_CSS

Device Defaults set to AUTO_DP

New Phone –> AUTO_DP –> AUTO_CSS –> AUTO_PT –> HelpDesk#

7. To minimize network distruptions, implement partitions and

CSSs in the following order:

1. Create Partitions
2. Create CSSs
3. Assign devices to CSSs
4. Assign numbers to partitions
(Remember: All CSSs can access the [none] partition)

Partitions and Calling search Spaces

Partitions and Calling search Spaces

Partitions: Groups of dialable numbers
-Route Patterns
-Anything that has a number

Calling Search Spaces (CSS): A list of Reachable Partitions
-Assigned to any ‘dialing’ entity
-Defines calling priviliges

By default all numbers are assigned to the [none] partition
By default all devices are assigned to the [none] CSS

This default allows everyone to call everyone by default

Practical Setup:

Three types of calling restriction should exist in your

– Lobby/Public phones: internal extensions only
– Typical users: internal and local pstn
– Management: internal, local, and long distance pstn

Step 1: Creat the Partitions
Step 2: Assign numbers to partitions
Step 3: Create CSSs
Step 4: Assign CSSs to devices

EXAMPLE CSS and Partitions:



Hunt Pilot Groups


Build from the bottom up:
Line Group
Hunt List
Hunt Pilot

RNA (Ring No Answer) Reversion Timeout – how long to ring before moving to next Line

Note on Urgent Priority check box, for example if you create 911 hunt pilot or route pattern and check this box, it will dial this number as soon as it matches the digits 911