OS6250 VoIP recommendations

[nikolami]

Hello,

what is the general recommendation for configuring VoIP on Alcatel OmniSwitch 6250 and OmniStack 6200:
- Mobile of fixed VLAN ports. In case that fixed VLAN ports are configured, tagged 802.1Q traffic is used for VoIP, and untagged traffic is used for data?
- Is there any difference for OmniStack 6200, since it doesn’t has AOS.
- On some newer AOS switches there is AutoQoS feature. Does anyone has experience with it?
- Since in network will be both models for access switches OS6200 and OS6250, I prefer to have similar configured features on both.
- Is mandatory or recommended to implement QoS for voice traffic? Any sample QoS related configuration will be useful.
- In case of implementing QoS on access switches, what is it necessity to implement QoS on distribution and central switches (on which is VoIP exchange connected)? Also, if anyone has some configuration it will be most appreciated?

I appreciate any advice regarding VoIP implantation on Alcatel switches?

Best wishes to all Forum’s members in New Year 2011.

nikolami

[silvio]

Hi Nikolami,
your question can't be answered in 5 minutes.... and there will be no general recommendation.

Firstly we have to separate: AOS R6 switches (like 6250, 6400, 6850) and OEM switche (6200).
Than mobile or fix or tagged at the edge ports (to phone with pc behind it) depends also from your phones, if you would like to use dhcp for it etc.

I prefere the following:
1) for vlan separation:
I use vlan rule with the vendor mac. All packets from alcatel will be allocated to voice vlan - all other to data vlan.
here an example:
>vlan 1 name "data"
>vlan 2 name "iptouch"
> vlan 1 port default 1/16
> vlan port mobile 1/16
> vlan 2 mac range 00:80:9f:00:00:00 00:80:9f:ff:ff:ff

> show mac-address-table 1/16
Legend: Mac Address: * = address not valid

Domain Vlan/SrvcId Mac Address Type Protocol Operation nterface
--------+--------------+---------------------+----------------+------------+--------------+----
VLAN 1 00:50:8b:f4:ae:d0 learned 806 bridging 1/16
VLAN 2 00:80:9f:56:7d:04 learned 806 bridging 1/16

Total number of Valid MAC addresses above = 2

2) for qos:
# L3 prio (mostly DSCP field = 46) has to sent the phone/pbx
# the switch ports has to trust this prio - at AOS switches all mobile and tagged ports are trusted - and in my config with vlan rule the ports a mobile

There are a lot of other solutions (with tagging, policy rules...). You should check the voice packets with wireshark at all point of the network that the dscp field is always set.

Description Auto Phones Priority:
"The feature provides for the automatic trusting of traffic originating from Alcatel IP phones. The capability is enabled by default. Thus the ingress 802.1p or DSCP value on the packet is trusted. Since Alcatel IP phone data is IP data only the DSCP value is used to determine priority both in a routing or bridging environment for non-Qtagged and Qtagged data. The 802.1p value in a Qtagged flow is only referenced if the default classification on the input port is set to 802.1p.
Guidelines:
The parameter identifying traffic as CSBU IP phone traffic is the source mac address of the data. Alcatel IP phones use the well known MAC ranges of 00:80:9F:54:xx:xx - 00:80:9F:64:xx:xx and 00:80:9F:66:xx:xx - 00:80:9F:6F:xx:xx. Additionally up to four user specified MACs or MAC ranges can be defined to receive the Alcatel IP phone QoS.
...
When auto phone is enabled, other priority rules concerning the phone traffic doesn’t take effect. Notice also that "qos phone trusted" only makes Alcatel IP Phone traffic trusted, so if the Alcatel Phone traffic doesn't have high DSCP value, it won't get into high priority queue. To set Alcatel IP Phone traffic priority, one needs to use "qos phone priority ..." command.
User can figure four additional MACs or MAC ranges to receive Auto Phones QoS."

you can check auto qos with
> show qos config

Config for 6200 is complete an other one. But also the best way is to trust the incoming prio of the voip packets:
console(config)# qos basic
console(config)# qos trust cos

I hope that is usefull
regards Silvio

[nikolami]

Hi Silvio,

you gave me comprehensive and very useful answer. So I have to read it several time.

For the first moment a couple of questions will be:
1. Since in network will be separate ports on switches for IP phones, IP cameras, PCs ..., do you think that the simplest way is the best: just to configure every port as untagged default port (on AOS switches), i.e. as untagged access port on OS6200 switches.

2. AutoQoS exist only on AOS switches, isn't it? And AutoQoS can be used only for Alcatel IP phones? What in case that IP phones and exchange are non Alcatel?

3. Generally, do you recommend implementing QoS? Since most access switches have 24 x 10/100 Mbps ports (just a couple of 48 x 10/100 Mbps switches) for users and 1 x 1000 for uplink. Since number of users will not be close to maximum number of ports I don't expect congestion on uplink ports. For now, IP telephony, access to Internet and company's applications are required services. In near future, IPTV service could be implement in the network.

4. For IPTV service is it necessary to implement QoS in opposite direction, from IPTV servers to end users ?

Best regards,

Nikolami

[silvio]

HI,
1. this is a very static config - but often used. Than you have to say f.e.: ports 1...16 for PC and 17...24 for phones
2. right - per default only Alcatel
but you have to know, that auto-qos only means the following:
the prio from incomming packets with prio (dscp >0) will be trusted, so it will be used for queue-allocation at the switch
-> if there is a prio set at the phone, than the switch will use this for priorisation
For other phones you can trust the "phone-ports" by yourself (see my first post).
If the phones don't sent prio than you can priorize the phone-ports also staticly
f.e.
> qos port 1/17-24 default dscp 63
> qos apply

3. QoS is always necessary, if you implement ip phones
4. you're right

regards
Silvio

[cedric1]

hello All
just one question :

if you use this : qos port 1/17-24 default dscp 63
so traffic coming on this port (pc + phone if a pc is connected behind a phone) will be set to prio dscp 63 if port is untrust mode

I have better think we need to enter this : qos phones priority 7
to be sure to put in high queue only mac member on the phone group.
with this config, know that packet are not marked with a dscp value but only put in high queue on the outup port on the local switch.

to add other mac vendor to the spec group :
The MAC group name “alaPhones” is a reserved group name used to identify the MAC addresses of IP phones

policy mac group mac_group mac_address [mask mac_mask] [mac_address2 [mask mac_mask2]...]
where mac_group = alaPhones

Let me know what do you think about this

so other way is to configure dscp on your phone, and put incoming port on the switch + uplink to trust mode.

I have done a xls sheet with matrice showing combination of trust/untrust/qos rule and status of inocm and outgoing packet result.
it stay on a other pc, i will post it.

Cedric

[silvio]

Hi,
I'm in the same opinion like cetric. Often I have seen that admin use the static config - fix ports for phones and fix ports for pc. But than you shouldn't install pc behind phone.

My prefered config is the following one:
vlan 2 name "phone"
vlan port mobile 1/5-24 (all ports except uplinks)
vlan 2 mac range 00:80:9f:00:00:00 00:80:9f:ff:ff:ff (mac-range of your phones)

So all phone-traffic is allocated to the vlan 2. Because all ports are mobile they are automaticly trusted.

If your phones are not able to sent a L3-prio (dscp) you have to make a policy like this:
policy condition FROM_VL2 source vlan 2
policy action SET_PRIO dscp 46
policy rule FROM_VL2 condition FROM_VL2 action SET_PRIO
qos apply

because your uplinks are tagged ports this ports are also automaticly trusted.
with this config you have a vlan-separation of voice and data and also qos for voice traffic.
All ports are equal, the switch detects the traffic of the phones.
regards Silvio

[cedric1]

Here file upload with qos config exemple

[ramdineshsunil]

Hi Silvio,

Thanks for your contribution on this post ,

i have similar concern like this,

I need to configure qos for voip phones (avaya phones) in 802.1q ports , could you check whether the below configuration is correct ,


vlan 2 name "phone"
qos enable
qos trust-ports
qos phones priority 7


policy condition FROM_VL2 source vlan 2
policy action SET_PRIO dscp 46
policy rule FROM_VL2 condition FROM_VL2 action SET_PRIO
qos apply

[silvio]

Hi,

qos enable

not necessary - because this is the default config at all switches - but is not wrong

qos trust-ports

with "trust" you trust all priorities inside the incomming packets.
This is fine, if you have configured pio in the phones and the pbx (f.e. DSCP/TOS).
Not necessary if (but also not wrong) if you have mobile ports (see below).

qos phones priority 7

Will not work at you because no Alcatel-phones. Prio 7 (the highest) is not a good idea - for phones we take 5.

policy condition FROM_VL2 source vlan 2
policy action SET_PRIO dscp 46
policy rule FROM_VL2 condition FROM_VL2 action SET_PRIO
qos apply

As always you have to deside: trust all ports (if the phones already sent the prio) OR set Pio for ALU Phones OR use a policy to prio all packets in vlan 2.
Your config will work but is no clean config.

But you have forgotten to tag all the ports for your phones. Best way is to make all ports mobile and allow mobile-tag for vlan 2. mobile ports are trusted by default. So you don't need the command to trust all ports.

vlan port mobile 1/1-48
vlan 2 mobile-tag enable

regards
Silvio