Wireless Access

Scenario1

if the packet is coming from the switch to the wireless controller

if it got a voice packet tagged with DSCP(not the default one you use on Wireless controller) does it pass the tag it has whatever it is to the AP?

Scenario2

if the packet goes from the AP to the controller it will tag it with DSCP 56 the controller will keep this tag automatically and pass it to the Switch... now on the switch i can take that DSCP value and maintain it all the way to the ip pbx or all around my network(so it will has priority) even if its using another DSCP value, but the issue with this is that if i got another thing inside the company let say that in the company DSCP 56 was assigned to video... then on the switches they willl have the same priority all over the wired network

What we want is to have the same DSCP value in all the system for my understanding thats is what we should do(im not an expert in QoS neither in Voice) thtas why im asking.

Extra Questions

1-Now if the company is already running another values for Voice and video guess is less work just changing them on the controller, on the WMM option on the SSID right?

2-When the packet is in the air let say i got an IP phone, and im using the same corporate SSID(not needing another SSID for voice like other brands)How does aruba recognize its a voice traffic? with application aware? how does it recognize is a voice traiffc? when im using WMM and the client support it i mean.

3-If the client does not support wmm i got no other option that on the firewall rule to put maybe the ports on a rule and the network its using and give it priority but the problem here is that i cannot use DSCP values on the rule i just can use TOS or 802.1p.   How can i manage that? if we are using on our switches DSCP values for priority.

Cheers

Carlos

Hi Carlos,

Please find my answers inline:

Scenario1

if the packet is coming from the switch to the wireless controller

if it got a voice packet tagged with DSCP(not the default one you use on Wireless controller) does it pass the tag it has whatever it is to the AP?

Yes, for downstream traffic, the DSCP value of the packets are retained

Scenario2

if the packet goes from the AP to the controller it will tag it with DSCP 56 the controller will keep this tag automatically and pass it to the Switch... now on the switch i can take that DSCP value and maintain it all the way to the ip pbx or all around my network(so it will has priority) even if its using another DSCP value, but the issue with this is that if i got another thing inside the company let say that in the company DSCP 56 was assigned to video... then on the switches they willl have the same priority all over the wired network

What we want is to have the same DSCP value in all the system for my understanding thats is what we should do(im not an expert in QoS neither in Voice) thtas why im asking.

Yes, if you configure 56 for voice as well as video in SSID profile, voice and video upstream traffic will use same DSCP-56

Extra Questions

1-Now if the company is already running another values for Voice and video guess is less work just changing them on the controller, on the WMM option on the SSID right?

Yes, If you want different DSCP values to be mapped for voice and video, you just need to map these in the SSID profile

2-When the packet is in the air let say i got an IP phone, and im using the same corporate SSID(not needing another SSID for voice like other brands)How does aruba recognize its a voice traffic? with application aware? how does it recognize is a voice traiffc? when im using WMM and the client support it i mean.

If the wmm priority is set to 6 or 7 in the packets from IP phone, then the traffic is considered as voice.

In addition to this, we can recognize voice traffic based on the ALG used by the IP phone

3-If the client does not support wmm i got no other option that on the firewall rule to put maybe the ports on a rule and the network its using and give it priority but the problem here is that i cannot use DSCP values on the rule i just can use TOS or 802.1p.   How can i manage that? if we are using on our switches DSCP values for priority.

I am not sure if I understood this question.  Did you mean that, you cannot use DSCP values because while creating a rule, the options available are 'tos' and 'dot1p-priority'? 

If so, on the aruba firewall rule, TOS is same as DSCP value. You can set the required DSCP value as TOS in your rule

Thanks,

Minnoo

Hello Thanks for answering my questions

I got more questions :)

To correctly enable WMM and configure it on the controller this are the things i  need to do

1-Go to ap group-->VAP-->SSID-->advance settings and check on wireless multimedia WMM(At this point WMM is configured and enable on the controller but with the default values which i can override them if i change the values on the DSCP mapping

2-I need to configure WMM for example on the IP phones, do i need something specific configured here? (i dont know too much about that thats why i ask you, but i call tell the one that ocnfigurs de ip pbx what i need but what i would need? enable WMM on them and do i need to configure an specific value or something? just an example of the ip phones you use it would be enough to explain the guy of the ip pbx.

Now besides this he willl pass the packet for example if i leave it on default  he willl pass this value to the switch(and well i just need to maintin that value through my switch network which i already know how to do it right? Or im missing something else?

I dont need to do anything else? as he will automatically know its a voice traffic comming from an ip phone as you saiid he will identify  voice traffic based on ALG?

Now for the case i got a mix of WWM clients and non WMM clients

For this case i need to create an specific rule

In this case

I would do a rule with the specific ports that uses the communications and tell them to all thise ports to use TOS in example TOS 56 ?(  i have read in the VRD that the normal values that they pick are 6 or 7 which is a total different value from teh DSCP... this is what it got me confused.... i read that the TOS is like the legacy  of DSCP...

Anyways in this case I would have many roles but in each role i would put this as the first firewall policy.

Anyways i would like to understand this correctly before going to the voip call admission control profile config...

If you can enlight me in this configuration i would be really thanksful

Cheers

Carlos

Re this,.... will it recognise ef46 that my clients are sending that is 802.1p tags i think?

2-When the packet is in the air let say i got an IP phone, and im using the same corporate SSID(not needing another SSID for voice like other brands)How does aruba recognize its a voice traffic? with application aware? how does it recognize is a voice traiffc? when im using WMM and the client support it i mean.

If the wmm priority is set to 6 or 7 in the packets from IP phone, then the traffic is considered as voice.

In addition to this, we can recognize voice traffic based on the ALG used by the IP phone

Anyone:)

There are ALGs in the controller that recognize SIP, Skinny, MGCP, H323, etc.  So, when a VoIP phone goes off hook, the controller sees the SIP call setup (or whatever signalling protocol you use, as long as it is well known) and begins prioritizing the RTP packets that follow on whatever ports the SIP conversation is happening.  The controller also tells the AP that there is a voice call going on and stops ARM scanning (if configured).

Is that what you are asking? 

No, we use the marking of EF46 on all our clients directly from the application. To our LAN this means voice and in our WAN it is proritised in this fashion. I want to know how when my client send this out that I can switch WMM on and WMM will know its voice and prioritise it in this fahsion. I realise I can change the 56 to something that mean EF46 so when it gets to the switchport the switch thinks its the same as usual....

Also, how does the 56 on the controller relate to EF46? it is siimply change 56 to 46?

---

@leelaw wrote:

Re this,.... will it recognise ef46 that my clients are sending that is 802.1p tags i think?

 

 

2-When the packet is in the air let say i got an IP phone, and im using the same corporate SSID(not needing another SSID for voice like other brands)How does aruba recognize its a voice traffic? with application aware? how does it recognize is a voice traiffc? when im using WMM and the client support it i mean.

 

If the wmm priority is set to 6 or 7 in the packets from IP phone, then the traffic is considered as voice.

In addition to this, we can recognize voice traffic based on the ALG used by the IP phone

_________________________________________________________________________________________________

you mean a packet coming from a wifi IPT ? I belive it will not use 46, it will use the 802.1p (which is a 3 bit field in the MAC layer of the packet and it will be used a long with WMM (it is part of WMM actually).

maybe the 46 is from the Telephony server or other IPT hand set that passed through the network already and reach the controller with DSCP value of 46 ?!

Yes, we mark the MS lync calls with EF46 on all our laptops.

in the SSID profile advanced tap, there is WMM and DSCP to WMM mapping.

because you are using voice and  EF46 (as you said),

in the ( DSCP mapping for

WMM voice AC ) field fill it with 46, then when controller read DSCP of 46 comming from your packet it will recognise it is a voice and assign it with 802.1p priority of 6 or 7 (which means voice).

I think that the controller marks it with that number oafter it has recognised it is a voice packet not the other way around?

yes, I agree. I thought it would do the same because I could not know how exactly using FW we can read DSCP on controller. Therefore, I expect that WMM DSCP mapping will be used in both direction (if traffic going from AP to switch (read 802.1p and map it to DSCP) from switch to AP ( read DSCP and map to 802.1p)).

I want to know, if this option (WMM to DSCP mapping) can work in both direction or just one direction from (AP to switch).!!

note this from UG:

Enable wireless multimedia and set a DSCP value for video traffic.
(host) (config)#wlan ssid-profile default
(host) (ssid-profile “default”)#wmm
(host) (ssid-profile “default”)#wmm-vi-dscp <value>
Example: (host) (ssid-profile “default”)#wmm-vi-dscp 40
(host) (SSID Profile "default") #show wlan ssid-profile default
SSID Profile "default"
----------------------
Parameter Value
--------- -----
SSID enable Enabled
ESSID building1-ap
...
...
...
Wireless Multimedia (WMM) Enabled
Wireless Multimedia U-APSD (WMM-UAPSD) Powersave Enabled
WMM TSPEC Min Inactivity Interval 0 msec
Override DSCP mappings for WMM clients Disabled
DSCP mapping for WMM voice AC 56
DSCP mapping for WMM video AC 40
...
...
...
Setting the DSCP value, tags the content as video stream that the APs can recognize. By default, the
DSCP value is set to 40.

(does not this suggest that it works from switch to AP ?)

Also, note the following (from aruba documents:

Policy Enforcement Firewall
The Aruba policy enforcement firewall (PEF) software module is an International Computer Security
Association (ICSA) labs-certified stateful firewall that allows policy to be applied to user traffic
sessions. In addition to the functions that are typically associated with firewalls, the Aruba PEF can
also reclassify traffic. Firewall policies and application layer gateways are used to dynamically
reclassify traffic to not only prevent abuse, but also to properly prioritize traffic that has not been
marked with the correct priority.

Unmarked Traffic
When traffic reaches the mobility controller with no DSCP or 802.1p marks, the traffic is compared to
the policy that is assigned to the user role. If the traffic falls within a class of traffic that normally would
be classified at a different level, such as for a voice session, the mobility controller remarks the traffic
and then forwards it (Figure 37). If the traffic is untagged and that is the correct state, the mobility
controller forwards the traffic unchanged (Figure 38).

Incoming Traffic Is Marked
When traffic arrives and it is already marked, those marks are compared to the system policy. If the
marks are correct for the policy and traffic type, the traffic is forwarded unchanged

Remarking Traffic to a Different Class
The third case occurs when traffic arrives but it is marked for an incorrect class. Sometimes
applications or servers are incorrectly set, or malicious users attempt to mark traffic at a different level
to take advantage of prioritization in the network. For example, game traffic is classed as voice for
better service. When the mobility controller identifies traffic that is marked at an incorrect class, it
retags the traffic to the appropriate priority level

FROM all of the above you have to : 1- use PEF, 2- compare it to traffic (using port number) 3- assign or re-assign DSCP and 802.1p values. (it is like the traffic it self should be verified and DSCP values received are not trusted).

So you can know it is voice by using port number (ALG)

 However, I want to be sure about the following when controller find it is voice will it put it into the high priority queue or should I make a rule ?! :S