Hey ccievoice1,
This was covered by a post in a bit of excess not a month ago (Jan 24
I believe) - but nevertheless I posted all of the scenarios and
calculations from that email below for your reference:
Scenario >> Voice Bandwidth( Layer 2 Overhead), [compress header ip
rtp] sampling rate - 20ms:
20 bytes <-- G.729 media payload>
2 bytes <-- L3/L4 Header Compressed with cRTP (Normal sizes WITHOUT
compression are 20 bytes for IP, 8 bytes for UDP, 12 bytes for RTP:
for a total of 40 bytes for the L3/L4 Header)>
+4 bytes <-- frame relay header
-------------
= 26 bytes
*8 bits per byte <-- convert to kilobits>
-------------
= 208 bits
*50 <-- based on 50 pps>
-------------
10,400 bits per second or 10.4kbps per G729 call
(round up to 11Kbps for QoS -- Always want to have slightly more
bandwidth - rather than less bandwidth reserved!)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Scenario >> Voice Bandwidth( Layer 2 Overhead), NO cRTP compression,
sampling rate - 20ms:
20 bytes <-- G.729 media payload>
40 bytes <-- L3/L4 Header Non-Compressed (20 bytes for IP, 8 bytes for
UDP, 12 bytes for RTP: for a total of 40 bytes for the L3/L4 Header)>
+4 bytes <-- frame relay header
-------------
= 64 bytes
*8 bits per byte <-- convert to kilobits>
-------------
= 512 bits
*50 <-- based on 50 pps>
-------------
25,600 bits per second or 25.6kbps per G729 call
(round up to 26Kbps for QoS)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Scenario >> Voice Bandwidth( Layer 2 Overhead), NO cRTP compression,
ADD Frame Relay Fragmentation (FRF.12), sampling rate - 20ms:
20 bytes <-- G.729 media payload>
40 bytes <-- L3/L4 Header Non-Compressed (20 bytes for IP, 8 bytes for
UDP, 12 bytes for RTP: for a total of 40 bytes for the L3/L4 Header)>
+8 bytes <-- frame relay header with FRF.12 compression
-------------
= 68 bytes
*8 bits per byte <-- convert to kilobits>
-------------
= 544 bits
*50 <-- based on 50 pps>
-------------
27,200 bits per second or 27.2kbps per G729 call
(round up to 28Kbps for QoS)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Scenario >> Voice Bandwidth( Layer 2 Overhead), NO cRTP compression,
ADD use MLPPP over Frame Relay, (No FRF.12 - not compatible with MLPPP
anyhow), sampling rate - 20ms:
20 bytes <-- G.729 media payload>
40 bytes <-- L3/L4 Header Non-Compressed (20 bytes for IP, 8 bytes for
UDP, 12 bytes for RTP: for a total of 40 bytes for the L3/L4 Header)>
13 bytes <-- MLPPP header
+8 bytes <-- frame relay header
-------------
= 77 bytes
*8 bits per byte <-- convert to kilobits>
-------------
= 616 bits
*50 <-- based on 50 pps>
-------------
30,800 bits per second or 30.8kbps per G729 call
(round up to 31Kbps for QoS)
Hope that helps some,
Mark Snow
CCIE #14073 (Voice, Security)
CCSI #31583
Senior Technical Instructor - IPexpert, Inc.
A Cisco Learning Partner - We Accept Learning Credits!
Telephone: +1.810.326.1444
Fax: +1.309.413.4097
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IPexpert - The Global Leader in Self-Study, Classroom-Based, Video On
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On Feb 15, 2008, at 9:58 AM, ccievoice1 wrote:
So, a default g729 call is: (20bytes payload + 40bytes header *
8bits) * 50pps = 2400 or 24K
So, if cRTP is used for a default g729 call, what would be the
calculation?
Thanks.
On Fri, Feb 15, 2008 at 3:56 AM, Vik Malhi <[EMAIL PROTECTED]>
wrote:
You can look at a table on page 33 of the QOS SRND for this
information.
Vik Malhi
CCIE Voice Instructor / Developer - IPexpert, Inc.
CCIE Voice #13890 CCSI #31584
URL: http://www.IPexpert.com
Toll Free: +1.866.225.8064
International: +1.810.326.1444
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
] On Behalf Of jason sung
Sent: Thursday, February 14, 2008 9:47 AM
To: boonchin .ng
Cc: CCIE Maillist
Subject: Re: [OSL | CCIE_Voice] QoS question
G729 on frame-relay with FR.12 is not 24K it is 28K
so your 5 g729 calls will be
5 x 28 = 140
On Thu, Feb 14, 2008 at 11:36 AM, boonchin .ng
<[EMAIL PROTECTED]> wrote:
Hi Jason,
Thanks for the explanation.
So, I would like to understand another scenario.
Similarly, I have a 384K frame-relay WAN link, so I have:
!
map-class frame-relay FRTS-384
frame-relay cir 364800
frame-relay bc 3648
frame-ralay be 0
frame-relay mincir 364800
frame-relay fragment 480
!
Now, for LLQ I want to configure to only prioritized 5 g729 calls:
!
policy-map LLQ
class media
priority x
class control
bandwidth 16
class class-default
fair-queue
!
So, the x value is 5 g729 calls. How can I calculate the x value?
Based on CCM bandwidth for a g729? x = 5 x 24
Please kindly advice.
Thanks.
---------- Forwarded message ----------
From: jason sung <[EMAIL PROTECTED]>
Date: Thu, Feb 14, 2008 at 11:26 PM
Subject: Re: [OSL | CCIE_Voice] QoS question
To: "boonchin .ng" <[EMAIL PROTECTED]>
Cc: CCIE Maillist <[email protected]>
When you have minCIR configured the LLQ picks 33% of that.
If you do not have minCIR configured than the CIR divided by two is
used in the calculation.
In your example, since you have mincir configured.
Priority bandwidth will be 364800 * .33 = about 120K
LLQ will allow you to configure 75% of the total bandwidth.
if you want to alter this, use the command
max-reserved bandwidth xxx
-Jason
On Thu, Feb 14, 2008 at 5:45 AM, boonchin .ng
<[EMAIL PROTECTED]> wrote:
Hi,
I have a 384K frame-relay link. Hence, I have:
!
map-class frame-relay FRTS-384
frame-relay cir 364800
frame-relay bc 3648
frame-ralay be 0
frame-relay mincir 364800
frame-relay fragment 480
!
Now, I want to do LLQ on voice, so:
!
policy-map LLQ
class media
priority percent 33
class control
bandwidth percent 5
class class-default
fair-queue
!
Question: In the policy-map LLQ, I have "bandwidth percent 5". So
can I assume that is 5% of the CIR value? If I want to use "priority
x" and "bandwidth y" without using the percent command, how I can
calculate the bandwidth value for class media and class control?
Thanks.
