asterisk users - Sep 2006 - Setting QOS settings in asterisk and/or CentOS?

How would I go about setting the TOS bit to "RTP IP TOS Byte:  18
(hex)"
for SIP and IAX traffic at the asterisk server?
 
Also, 
Do you have a quick reference on how to configure a Cisco switch to
prioritize SIP traffic?
I check in various Cisco docs, and there are so many references, and
none of them seem to relate directly to using the TOS bit for QOS.
 
I am looking into using the TOS bit because that is the only method that
my SIP devices use. (Citel Handset Gateway)
 
ref:
QOS settings from Citel Handset Gateway:
Handset Gateway - QoS Configuration

IP Type of Service 
RTP IP TOS Byte:  18 (hex) 

Silence Suppression 
Mute Mode: On, UDP keep-alive every 10 seconds
G.711 Voice Activity Detection: Off

Codec Preferences 
G.711u: 1 (Highest priority) 
G.711a: 2
 
 

Thank You,

Steven BerkHolz
- MCSA - MCSE -
Manager of Information Systems
TESCO Group Companies
Fax. 248-836-5101
www.TESCOGroup.com

Board member of
www.glimasoutheast.org

 
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Hello,
 
For the Cisco QOS:
 
Based on a Cisco Router all you need is a simple access-list. 
 
class-map match-any voip-class
    match ip rtp 10001 9999
    match access-group 150
!
!
policy-map voip-policy
    class voip-class
    priority xxx (in Kbits)
 
access-list 150 permit udp any any eq 5060
access-list 150 permit udp any any eq 4569
 
Voila!
 
Redouane

________________________________

De : BerkHolz, Steven [mailto:StevenBerkHolz@TESCOGroup.com] 
Envoy? : jeudi 21 septembre 2006 15:33
? : asterisk-users@lists.digium.com
Objet : [asterisk-users] Setting QOS settings in asterisk and/or CentOS?


How would I go about setting the TOS bit to "RTP IP TOS Byte:  18
(hex)" for SIP and IAX traffic at the asterisk server?
 
Also, 
Do you have a quick reference on how to configure a Cisco switch to prioritize
SIP traffic?
I check in various Cisco docs, and there are so many references, and none of
them seem to relate directly to using the TOS bit for QOS.
 
I am looking into using the TOS bit because that is the only method that my SIP
devices use. (Citel Handset Gateway)
 
ref:
QOS settings from Citel Handset Gateway:
Handset Gateway - QoS Configuration

IP Type of Service 
RTP IP TOS Byte:  18 (hex) 

Silence Suppression 
Mute Mode: On, UDP keep-alive every 10 seconds
G.711 Voice Activity Detection: Off

Codec Preferences 
G.711u: 1 (Highest priority) 
G.711a: 2
 
 

Thank You,

Steven BerkHolz
- MCSA - MCSE -
Manager of Information Systems
TESCO Group Companies
Fax. 248-836-5101
www.TESCOGroup.com

Board member of
www.glimasoutheast.org

 
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I use the following in rc.local for setting tos bits using iptables:iptables -A
POSTROUTING -t mangle -p udp -m udp --sport 10000:20000 -j DSCP --set-dscp
0x2eWorks like a champ!>    1. RE: Setting QOS settings in asterisk and/or
CentOS?>       (Redouane Doumer)> De : BerkHolz, Steven
[mailto:StevenBerkHolz@TESCOGroup.com] > Envoy? : jeudi 21 septembre 2006
15:33> ? : asterisk-users@lists.digium.com> Objet : [asterisk-users]
Setting QOS settings in asterisk and/or CentOS?> > > How would I go
about setting the TOS bit to "RTP IP TOS Byte:  18 (hex)" for SIP and
IAX traffic at the asterisk server?>  > Also, > Do you have a quick
reference on how to configure a Cisco switch to prioritize SIP traffic?> I
check in various Cisco docs, and there are so many references, and none of them
seem to relate directly to using the TOS bit for QOS.>  > I am looking
into using the TOS bit because that is the only method that my SIP devices use.
(Citel Handset Gateway)>  > ref:> QOS settings from Citel Handset
Gateway:> Handset Gateway - QoS Configuration> > IP Type of Service
> RTP IP TOS Byte:  18 (hex) > > Silence Suppression > Mute Mode:
On, UDP keep-alive every 10 seconds> G.711 Voice Activity Detection: Off>
> Codec Preferences > G.711u: 1 (Highest priority) > G.711a: 2> 
>  > > Thank You,> > Steven BerkHolz> - MCSA - MCSE ->
Manager of Information Systems> TESCO Group Companies> Fax.
248-836-5101> www.TESCOGroup.com
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BerkHolz, Steven wrote:
> How would I go about setting the TOS bit to "RTP IP TOS Byte:  18 
> (hex)" for SIP and IAX traffic at the asterisk server?
    We do it by setting the DSCP value to 40, which sets the TOS bit to 
5 using iptables. Here's our rules_save for these opertations:

[350334:180338667] -A OUTPUT -p udp -m udp --dport 5060 -j DSCP 
--set-dscp 0x28
[12085728:2417094759] -A OUTPUT -p udp -m udp --sport 10000:20000 -j 
DSCP --set-dscp 0x28
[4531:356102] -A OUTPUT -p udp -m udp --sport 4569 -j DSCP --set-dscp 0x28
[4531:356102] -A OUTPUT -p udp -m udp --dport 4569 -j DSCP --set-dscp 0x28

which sets the TOS bit on all IAX, SIP and RTP packets. Using iptables 
means that we can set up our rules on the router without using ACLs. Our 
Cisco Cookbook (http://www.oreilly.com/catalog/ciscockbk/) has a nice 
section on QoS (Chapter 11) and an appendix on TOS, etc. The author 
advises not to use ACLs when possible as they take more CPU in the 
router to implement and on a heavily loaded router can cause packet 
delays. So here's what our config looks like:

class-map match-any Class-A
description Voice (IPP Critical)
 match ip precedence 5
 match protocol rtp
!
!
policy-map MPLS
 class Class-A
  bandwidth percent 25
 class class-default
  fair-queue 512
  random-detect

Then you just apply the policy-map to the outgoing interface.

Cheers,
Bob

-- 
				Bob Amen
			    O'Reilly Media, Inc.
			    http://www.ora.com/
			  http://www.oreilly.com/

BerkHolz, Steven wrote:
> How would I go about setting the TOS bit to "RTP IP TOS Byte:  18
(hex)"
> for SIP and IAX traffic at the asterisk server?
>  
> Also,
> Do you have a quick reference on how to configure a Cisco switch to 
> prioritize SIP traffic?
> I check in various Cisco docs, and there are so many references, and 
> none of them seem to relate directly to using the TOS bit for QOS.
>  
> I am looking into using the TOS bit because that is the only method that 
> my SIP devices use. (Citel Handset Gateway)
For asterisk, take a look at sip.conf.sample and you'll find something 
like this for v1.2 and earlier:
  tos=lowdelay    ;ox18 sets ip tos bits (=lowdelay, throughput)

After v1.2, the look in the asterisk/docs directory and you'll find a 
readme file relative to QoS. The format of the QoS parameters have 
changed from the older TOS bits to the newer terminology Differentiated 
Services, and coding within sip.conf looks something like this:
  tos_sip=cs3
  tos_audio=ef

Differentiated Services is a superset of TOS; anything you want to do in 
TOS bits have an equivalent in Differentiated Services, and the bits map 
exactly.

The cisco web site has a very significant amount of documentation for 
configuring routers and switches for QoS, and they have a very excellent 
700+ page book that is oriented 100% towards implementing QoS on various 
cisco boxes. Cisco's search engine leaves something to be desired in 
some cases, but the info you want is there.

Not all cisco switches have the same QoS implementations. For example, 
most of the workgroup type switches support something like 3 or 4 
outbound queues, while the higher end switches support more queues. If 
you're going to deal with RTP only from a QoS perspective, you only need 
two queues (eg, RTP & Default). The Default queue (or Class) is a 
special case that includes everything not in other queues.

For the most part, QoS on switches is not required unless: a) trunk port 
traffic exceeds the bandwidth available (for that port), or, b) outbound 
port is a slower speed then the majority of other switch ports (eg, 
congestion).