QoS - DSCP or CoS

Our Environment:
-We have about 200 Polycom VoIP phones (SoundPoint IP335). These phones utilize DSCP - EF. However, CDP is currently disabled by our provider. These phones are 100% cloud managed. Every call, even the internal between two local phones has to go out to the cloud and back.
-We have 53 Cisco access points AIR-CAP3502I-A-K9 connected to our Cisco WLC-5508 controllers.
-We have 2960-S stackable access layer switches as well as primary and secondary L2/L3 Core switches WS-C3560E-12D-E.
OUR GOALS:
1. We would like to implement an End-To-End QoS solution in our environment utilizing the Auto QoS configuration macros for both the Wi-Fi Access Points that use QoS and WiFi Controllers.
2. We would like to implement an End-To-End QoS solution in our environment utilizing the Auto QoS configuration macros for our VoIP phones.
Proposed solution:
1. Enable QoS on ALL switches and ultimately Routers by using :
mls qos
2. On the switchports facing the Access Points use:
mls qos trust dscp
3. On the switchport facing the Polycom VoIP phones use:
auto qos voip trust
mls qos trust dscp
4. On the trunks between the access layers switches and our Cores, we would like to use DSCP. Lots of different documentations state to use CoS should be used acrooss layer 2 uplinks and that DSCP should be used across Layer 3 uplinks. However, DSCP is able to pass these layer 2 links without any rewrite by CoS. Trunks between all L2/L3 switches would be configured as follows:
auto qos voip trust
mls qos trust dscp
Questions:
-is this configuration valid?
-Is this design future-proof enough so that it NOT only serves the VoIP traffic in the future but other traffic possible future traffic such as video, and etc.
-Should we be using CoS vs. DSCP?
-i noticed that our 2960-S switches have "auto qos srnd4" configured BUT our
Core Switches don't. Should this be enabled on the Core switches as well? I noticed that "auto qos srnd4" enabled causes our 2960S switches change the "auto qos voip trust" being displayed in the running configuration as "auto qos trust". Not sure why is this happening. But if you turn off "auto qos srnd4" the command sticks and it is shown properly within the 2060-S running config.
Thanks.

Hello.
I doubt if "auto qos voip trust" would suit you on inter-switch links, as per documentation the command applies policy-map that gives only 320K for voice and signalling traffic (+ remarking exceeded traffic to BE).
If you want to protect your video traffic in the future, you will have to design new QoS policy and apply it per link.
Regarding "trust dscp" toward WLC/AP - if you configure this, all your laptops will be able to inject marked traffic into your network, abusing your QoS policy; that is why the best practice for VoIP phones is to be placed into dedicated voice VLAN + trust cos (not dscp).
PS: I would suggest you to try the command[s] on one switch and see what configuration will be applied per port (+global).

Similar Messages

QoS - can u trust dscp and cos?

Hello,
is it possible to trust DSCP and COS at the same time?
If so, which one wins?

G'day,
It does not really make sense to trust both DSCP and CoS at the same time. You configure your switch to trust one or none of these.
As an example, if you did have the capability to trust both DSCP and CoS, imagine what would happen if you received a frame with DSCP EF and CoS 0 ? You would be faced with a conflicting situation ... if you trusted CoS, you would give a potentially high-priority packet lesser service. Whereas if you trusted DSCP, you could end up giving a potentially low-priority packet voice-like service... So the option of trusting both is not allowed.
Hope that helps - pls rate the post if it does.
Paresh

DSCP to CoS mapping: Avaya traffic

It appears that Avaya marks its voice traffic as follows:
L2 signaling cos 6 L3 signaling dscp 34
L2 audio cod 6 L3 audio dscp 46
Has anyone interacted with theses settings and what are the right mappings for 6500 series Modules?
I am about to use the following:
#mls qos map dscp-cos 34 46 to 6
#mls qos map dscp-cos 48 to 5 "move IP control to cos 5)
#mls qos map cos-dscp 0 8 16 24 32 46 48 56 leave cos to dscp unchanged.
Finally use: #mls qos thrust dscp on input interfaces.
Can anyone clarify?
Thanks.

The 6608 and 6624 internal port is treated as trust-cos to the Catalyst 6000. So the default COS-to-DSCP mapping of the cards will determine the DSCP values with which the IP packets are marked unless they are changed in the switch.
The 6608 and 6624 will tag packets as follows:
COS = 5 for rtp traffic
COS = 3 for signalling traffic
By default on the Catalyst 6000, these COS values map in IP packets to DSCP 24 (COS = 3) and 40 (COS = 5) as shown in the table below.
Generally, the recommended DSCP values to use in a VoIP network differ slightly. They are:
DSCP = 46 for rtp traffic (Recommended Expedited Forwarding (EF) value)
COS = 26 for signalling traffic (AF31)
It may be necessary to change the default COS-DSCP mapping on the Catalyst 6000 so that the DSCP markings in packets generated by the 6608 and 6624 cards conform to the network policy. For example, if other devices in the network are marking packets with the recommended values.
Information on how to change the default COS-DSCP mapping is provided in the Mapping Received CoS Values to Internal DSCP Values section of Catalyst 6000 Family Software Configuration Guide.

DSCP and CoS mapping to use uAPSD

Hi CISCO experts, I'm trying to map some traffic to a DSCP and CoS priority. The fact is that doesn't work.
Steps:
1.Set personal filter (myfilter)to forward from specific IP.
2.Set QoS policy: my_policy --> myfilter-CoS (4).
3. Add policy to 802.11g.
When I look up the IP traces DSCP is allways 0x00 (Best Efford).
If I map DSCP (best efford) to DSCP (vocie) doesnt work either.
What can I do? Im trying to emulate AC_VO or AC_VE so I can force the uAPSD protocol to work.
Best regards

Are you using a Cisco WLAN controller or autonomous AP?
You would need to ensure that the RTP (voice) packets to the AP has DSCP = EF.
There is an auto policy in the WLAN controller to map EF to UP6.
For autonomous, will need to create a QoS policy to do this.
But you do not want to map DSCP = 0 to UP6!
This defeats the purpose.
Will only want RTP packets to be marked as EF.
See the WLAN SRND and 7921G Deployment Guides for more info.
http://www.cisco.com/application/pdf/en/us/guest/netsol/ns279/c649/ccmigration_09186a00808d9330.pdf
http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7921g/5_0/english/install/guide/7921dply.pdf

QoS trust dscp or cos on catalyst 4500

We have a 4510R with Cisco IOS Software, IOS-XE Software, Catalyst 4500 L3 Switch Software cat4500e-UNIVERSALK9-M), Version 03.05.02.E RELEASE SOFTWARE (fc1).
I want use qos trust dscp or qos trust cos on the interface conected to other cisco switch or wlan controller.
The current IOS version, do not support qos trust dscp:
SW(config)#interface gi10/16
SW(config-if)#qos tr
SW(config-if)#qos trust ?
device trusted device class
extend Extend trust through a connected device
SW(config-if)#qos trust device ?
cisco-phone   Cisco IP Phone
cts           Cisco-telepresence
ip-camera     Cisco video surveillance camera
media-player Cisco Digital Media Player
SW(config-if)#qos trust device
What is the software that I need for this?. I tried with command lookup tool but the cat4500 do not appears.

That is even new for me.
I did a search and found that, now a days you no longer have to provide the Trust DSCP command, it is by default trusted.
Went through this White Paper and excerpts are below:
http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-4500-series-switches/white_paper_c11-539588.html
The answer to your question comes from the following excerpt :-
"Previously supervisor engines relied on “port trust” to classify traffic; however, this does not fall into the MQC CLI construct. MQC provides a more flexible capability, i.e. all traffic is trusted by default, an administrator can change this trust state using a policy map. Another difference is the “internal DSCP” value used within the switch to place packets in the proper queue.
Cisco Catalyst 4500E Supervisor Engines do not use “internal DSCP”; rather, it relies on explicit matching of QoS values using class maps so that packets can be placed in the correct queue.
Also, note that there is no specific priority queue: it is not queue 3 or queue 1. The priority queue is simply configured within a class; therefore, it is not tied to a specific queue. One final difference is that of classification. Cisco Catalyst 4500E Supervisor Engines provide sequential classification rather than parallel. This allows the network administrator to classify traffic at egress based on the ingress markings. These markings can be done unconditionally, using a policer or using a table map. Based on these changes, QoS CLI will now be more contiguous on the Supervisor Engines as it will now have standard Cisco MQC CLI, making configuration management much simpler"
HTH,
Please rate all helpful posts.
Regards

Wireless QoS - DSCP to 802.11e translation

Hi,
Would appreciate some advice, I am using a 5508 controller, I have an SSID that has WMM enabled and platinum QoS profile applied, with default settings. I have 802.11p set to none as we are not doing layer 2 QoS on the switches.
I found that when pinging a wireless client with DSCP set to EF the packets (all packets in fact) are being sent from the AP to the client with 802.11e set to zero. I verified this via AirPCAP.
Can someone confirm why the AP is not taking the DSCP marking from the outer LWAPP IP header and translating it to an 802.11e value?
My best guess is that I need to enable 802.11p on the QoS profile in order for the AP to start translating DSCP to 802.11e. The thing is that I don't particularly want to mark 802.11p as we will not be enabling QoS on the switches, and my understanding is that it's not really required in order for DSCP to be translated from the outer LWAPP IP header to the 802.11e field.
I've reviewed the Cisco documentation on wireless QoS, including the diagram showing the packet flow and copying of QoS markings at each step....
Thanks in advance,
Pete

Hi Pete,
If you are not enable QoS & disable re-write of DSCP on your switches, pretty much you will get the incoming packet DSCP when it leaves any switchport. Therefore WLC should get DSCP EF packets & outer CAPWAP should have DSCP EF. I have done a quick test to simulate your issue. WLAN configured for platinum QoS profile with 802.1p set to none. Wired PC - RTP traffic mark to EF in my case (as windows 7 does not correctly classify traffic).
1. Wired PC (IPCommunicator) ->Switch with no QoS -> AP -> Wireless client (7921 phone)
2. Wired PC (IPCommunicator) ->Switch with no QoS -> AP -> Wireless client (Laptop with IPC)
When I capture traffic for Cisco wireless phone I can see wireless frame is having UP value of "6-Voice". But when I do the testing for wirless laptop client I observed wireless frame are having UP of "0 - Best Effort" (as you observed as well). I would expected in both cases wireless frame UP to be zero. Not sure why behaviour differnt for Cisco 7921 phone.
Then I enabled QoS on the switch & trust DSCP on AP & wired PC connected port & CoS on WLC connected switch port. But left QoS profile 802.1p tag as " None". This time in both scenarios I have observed WMM_UP value "0-Best Effort" in wireless frames even though the AP received outer CAPWAP as EF. This is normal behaviour as QoS profile set to 802.1p to none & therefore outer CAPWAP will not translate to UP=6 as it is. It will cap to max of 802.1p configured (presumed none mean 0)
Finally when I set 802.1p tag to 6 on QoS profile & conduct the same test. I expected in both scenarios UP=6 for EF marked traffic to wireless client (cisco phone or wireless laptop). As expected Cisco phone received wireless frame had UP=6 Voice, but wireless laptop received frame had UP=0 best effort.
I am geussing this due to some kind of WMM incompatibility of different devices (not sure though). I will try to do this with some other clients ( jabber in iPhone & Galaxy SIII) & see any common behaviour.
As per the VoWLAN 4.1 design guide (page 2-18,19) 802.1p classification in QoS profile controll two behaviours
1. Determine what class of service (CoS) value is used for packets initiated from the WLC.
2. Determine the maximum CoS value that can be used by clients connected to that WLAN.
Regarding the QoS profile & traffic mapping, If you set your QoS profile to "Silver with 802.1p Tag of 3" & your wilreless clients' EF marked traffic (ie WMM_UP of 6) will translate into outer CAPWAP DSCP value of AF21 by AP. Same applicable to any video traffic from wireless clients (as it comes with WMM_UP of 4 or 5). But original packet's inner DSCP value remain as it is because of CAPWAP encapsulation from AP -> WLC. Due to this within wired network (at least from AP to WLC) you cannot differentiate Voice , Video packets as all having same DSCP value (AF21). Anyway in your case this won't matter as you do not do any prioratization of your traffic within your switch network.
Just for curiosity why do not you use qos on your switches ? is there any reason ? How do you prioratize your voice traffic over any other type of traffic in your network ?
I am running WLC 4402 with code 7.0.116. What is the software version you are running on your WLC ?
When it comes to software version 7.4 code, cisco introduced "Application Visibilty & Control" feature where you can classify traffic at the WLC as you normally do in wired switches. This will allow reclassify, markdown, drop traffic according to traffic categories.
HTH
Rasika

DSCP vs CoS

I need to think outloud here, just to make sure I have my barings right.
CoS is stored in the vlan tag, DSCP is stored in the IP header. So, if I have a phone or an app that can insert a DSCP value into the IP header and then trust all of the uplinks to my destination, when, how or why would CoS ever come into the picture? Looking into deploying QoS on both wired and wireless networks and want to solidify my understanding.

Disclaimer
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
Liability Disclaimer
In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
Posting
So, if I have a phone or an app that can insert a DSCP value into the IP header and then trust all of the uplinks to my destination, when, how or why would CoS ever come into the picture?
If L3 ToS is supported, the only reason to really used L2 Cos is when L3 ToS is not supported. (E.g. "pure" L2 switches.)

Qos DSCP value 46 gone, after enabling Remote Desktop Services on Windows 2012 R2 Standard

Hi,
After installing a clean Windows Server 2012 R2 with
all Windows updates I have setup Policy-Based QoS for tagging defined traffic,
in the test case all traffic to one specific ip address. Whireshark logging
displays the correct configured (46) dscp value so the group policy is
working fine. After installing Remote Desktop Services the Policy-Based QoS is
still in place but Wireshark results that the value is 0.
Can somebody explain why this happens and how to solve
it?
Regards, Edward

Hi Edward,
Thank you for posting in Windows Server Forum.
Did you find any related error for your case?
By default, Windows traffic has a DSCP value of 0. Network routers use the DSCP value to classify network packets and to queue them appropriately. The number of queues and their prioritization behavior needs to be designed as part of your organization's QoS
strategy. For example, your organization may choose to have five queues: latency-sensitive traffic, control traffic, business critical traffic, best effort traffic, and bulk data transfer traffic.
More information, please see:
Policy-based Quality of Service (QoS)
http://technet.microsoft.com/en-us/library/dd919203(v=ws.10).aspx
Hope it helps!
Thanks.
Dharmesh Solanki
TechNet Community Support
Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact [email protected]

URGENT! Setting QoS DSCP value on switches

Hi,
I desperately need replies to my problem below.
I tried to set DSCP values to 2 applications, video and video conference, on cisco 3560 and cisco 2950 swtiches based on the source ip address of the servers.
So on the switches, I created an access-list to identify the servers' ip addresses.
Then I use "class-map match-any video" followed by "match access-group" for the access-list.
Then I use "policy-map policy1", then "class video" then "set dscp ef".
Finally I apply the policy to the INPUTS of all ports "service-policy input policy1"
But when I use a sniffer to sniff the ports, I see that the DSCP value is not "EF", instead it is "0x20, class 4".
Why is this so?
Where have I done wrongly?
Finally, on routers, where do I apply QOS policy? On input ports or output ports of routers?
I urgently need help.
Thank you.
Regards,
Rachel

Rachel,
Without seeing what you have in place so far, I'll see if I can answer some of those questions. If the switch connects to a router, then the outbound (egress) interface would in fact be that interface on the switch that connects to a router. Best practices dictate that the classification and marking should be done on the inbound (ingress) interface which connects the switch to the network where the host resides.
If you wanted to implement an end-to-end QoS solution, then you should configure QoS on every interface between the source and destination. This is because even FastE/GigE ports can become congested due to worm outbreak or DOS attack. But if all you want to do right now is guarantee bandwidth to the video traffic across the WAN, that can be accomplished by a) classifying and marking the video traffic as close to the source as possible, and b) configuring queuing/scheduling on the outbound WAN interface based on those markings.
Once the switch has marked the traffic with a DSCP value per (a), that DSCP value should remain intact until it reaches the WAN router per (b), and all the way until it reaches its destination. That is, unless there is a device somewhere in between that is remarking traffic. If the switch you reference is not directly connected to the router you reference, there could be another switch or router in between marking everything back to DSCP 0, meaning that all traffic is untrusted.
I don't have a 2950 here with me, but without checking syntax this is basically what you should have, if you just want to mark video traffic EF and then guarantee bandwidth on the wan:
2950:
access-list permit
class-map match-any VIDEO
match access-group
policy-map POLICY1
class VIDEO
set ip dscp 46 !
interface
service-policy input POLICY1
Router:
class-map match-any EF_VIDEO
match ip dscp 46
policy-map VIDEO_OUT
class EF_VIDEO
priority 1600
interface
service-policy output VIDEO_OUT
If you are sniffing traffic on that switch to ensure that video traffic is being marked, make sure that you are sniffing the outbound interface toward the router, not the inbound interface from the host. That will ensure that your sniffer trace picks up the traffic after it has been marked DSCP 46.
Just in case this post is related to your post where you want to lock the router WAN interface so that the 1.6 megs of video gets through but other traffic is dropped when the video takes the full 1.6 megs of bandwidth...
QoS queuing/scheduling only kicks in when the interface experiences congestion. If there is no congestion on the interface, traffic will still be marked and policed per the service policy, but not queued/scheduled - it will just fly right through the interface with the new markings. The only way to force such congestion at 1.6 megs is to use traffic shaping. You would need to shape the entire interface down to 1.6 megs, and THEN apply the priority bandwidth. This can be accomplished with a hierarchical policy-map as follows:
Router:
class-map match-any EF_VIDEO
match ip dscp 46
policy-map VIDEO_OUT
class EF_VIDEO
priority 1600
policy-map SHAPE_OUT
class class-default
shape average 1600000
service-policy VIDEO_OUT
interface
service-policy output SHAPE_OUT
I really hope I am helping you out here, please let me know how this works out. Good luck!
Best Regards
Robert

QoS - DSCP - Classifying the packets

Hi,
I have set up a practice lab in GNS3 for understanding "Classifying & Marking" DSCP values. The topology is like this:
(R2)---------f0/0(R1)f0/1----------(R3)
R2 has two loopback interfaces with IP addresses 172.1.2.100/25 for loopback0 & 172.1.2.200/25 for loopback1
R3 has tow loopback interfaces with IP addresses 172.1.3.100/25 for loopback0 & 172.1.3.200/25 for loopback1
When Telnet Session is initiated from R2's 172.1.2.100 to R3's 172.1.3.100, R1 should mark the egress IP packet out of fa0/1 with DSCP value of 10(AF11).
The truncated configuration is as follows:
ip access-list extended MyTraffic
permit ip 172.1.2.0 0.0.0.127 172.1.3.0 0.0.0.127
class-map match-all test3
match access-group name MyTraffic
match protocol telnet
policy-map p3
class test3
set ip dscp af11
interface FastEthernet0/1
ip address 10.1.3.1 255.255.255.128
duplex auto
speed auto
service-policy output p3
The configuration works all right, but when telnet session is initiated from R2's 172.1.2.200 to R3's 172.1.3.200, the egress IP Packet out of fa0/1
is found with the DSCP value of 110000 (Class selector 6), where it should be 000000 (Best Effort Delivery) isn't it..???
This is the first time I'm posting on forums, kindly help me in understanding this..!!

Hi - this forum is for Cisco Modeling Labs. Please refer to the GNS3 forum for answers to those questions.

Mls qos trust{cos/ip-precedence/dscp} command

Hi every body!
I have few questions
1)
The command " mls qos trust dscp" is only valid on mulilayer switch or it is also valid for layer 2 switch? If layer 2 switch is configured with that command, can it modify the dcsp value based on policy?
2)is the following correct:
switch(config-if) mls qos trust dscp
switch will set the cos value to set default. If the default set is zero, then frame will be processed by best-effort delivery.
But the egress-queue will be decided by dscp value in the packet. A dscp to cos map will be used to drive the cos value and then frame will be placed in the queue that corresponds to cos value.( off course if egress port is configured for trunk)
thanks a lot and I wish America and all of you a happy new year!
thanks a lot!

Sarah
1) L2 switches can trust the dscp marking as well. The 2960 is a layer 2 only switch and the default is untrusted but if you then enter
"mls qos trusted" you have a choice of 'cos|dscp|ip-precedence'. The default if no choice is entered is DSCP.
2) If "mls qos trust dscp" is entered then the switch will use the DSCP marking found in the packet. This will then be used as the internal DSCP marking that all switches use. Unless you have a DSCP-DSCP mutation map the value used will be the value received in the packet.
Jon

Question about 3750 mls qos map dscp-output-q and cos-output-q

1. If a egress packet has both Cos and Dscp setting, which map should this packet used to put into queue?
2. The 3750 is doing ip route. After the packet is routed, will the packet keep the DSCP and COS? Or it will just keep the DSCP and using the dscp-cos map to create a new COS.

Apologies for the confusion with the terminalogy.
The question is where you have configured the trust boundaries, do you necessarily trust the DSCP value prior to being routed across your network?
Therefore, although you have explicity trusted the DSCP value, do you still trust the value at the remote peer.
For example, you connect into an MPLS with QoS enabled, you know that the values you are trusting are correct within your network, however at the remote peer/branch they could be remarked by the provider. Therefore do you 'believe' the values, or do you simply not trust them and then reclassify on ingress.
Regards
Allan.
Hope this makes sense..

Is it possible to configure non-default NX7K CoS-DSCP map?

NX7K QoS has system defined table maps for CoS to DSCP mapping, DSCP to CoS mapping, etc. Those table maps can be used in qos policy maps. I was wondering if I can change, for example, CoS to DSCP mapping to something different from the default values.
Somthing similar to Catalyst switch command "mls qos map cos-dscp 0 10 18 24 34 46 48 56", where you can define any CoS to DSCP values. I don't think this is possible in NX7K QoS, but just curious.
Thanks
Gary

Hi Raymond,
Based on my research, we can use Group Policy and Internet Options to configure default mail client.
How to make Outlook the default mail client
http://support.microsoft.com/kb/223877/en-us
How to configure the default e-mail client using Group Policy
http://support.microsoft.com/kb/2008044
Best Regards,
Amy
Please remember to mark the replies as answers if they help and un-mark them if they provide no help. If you have feedback for TechNet Subscriber Support, contact [email protected]

QoS: make switch to trust PC's DSCP marking

Hi,
As you all know, it's possible to override 802.1p/CoS field coming from PC attached to Catalyst switch.
This is accomplished in 2 (two) ways:
- either by '(config-if)# mls qos trust extend cos <value>'
- or via '(config-if)# switchport priority extend cos <value>'
But what about to make Cisco IP Phone to trust PC's DSCP marking ? Is this possible ?
P.S.
Can you also explain, why there 2 (two) flavors of CLI to allow switch to trust to PC's 802.1p marking ?
Thanks.

Tobi,
the PC basically send untagged frames to the switch, these will normally be send as CoS=0.
the following link has some scenarios for you
http://www.cisco.com/en/US/partner/products/hw/switches/ps5023/products_tech_note09186a0080883f9e.shtml#cg211
I think you will find example 6 usefull

Cisco 3560 switch| mls qos trust dscp question

Hi everybody
Hi everybody .
Please consider the following example:
3560 sw f1/1--------trunk---SW2
3560 sw
f1/1
mls qos trust dscp
3560 is using default cos-dscp map, assume a 3560 receives a frame carrying IP packet on f1/1 with COS 4, what will 3560 switch do?
1) will it use its default cos --dscp map ( cos 4--.dscp 32) and rewrite 32 in dscp field of the packet in the frame and provide PHB for dscp 32 ?
Much appreciated!!
Have a great weekend.

Hi
No it will not trust the cos value, because You have configured to trust dcsp. So, the switch will trust the dcsp value in the incoming frame.
/Mikael

QoS - DSCP or CoS

Similar Messages

Maybe you are looking for