We manage a 10 node network with a 501 (DSL 768 both ways)at each remote site and a 506 (Dedicated T-1) at the headquarters. The 506 is plugged into a Catalyst 3750 with enhanced software on it (I think EIM?). Since we have our mail server sending traffice across the 506 and our Avaya VoIP system sending packets across the 506 to phones at each remote site I want to prioritize the VoIP packets on the 3750 port that is uplinked to the 506. How would I do this. Right now we have not made a single config change to the Catalyst. Any ideas?
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Packet Prioritization
- Thread starter 5ascent0
- Start date
You will want to look into QOS.
Check out this article for examples:
Check out this article for examples:
- Thread starter
- #3
Dear Sir,
I may have some helpful info for you on this...
I just completed the rollout of Layer-2 QoS (meaning Cisco Catalyst switches only) on a global network, which uses Avaya IP telephony and "3750's" as you've mentioned.
The 3750 is an excellent device on which to learn and deploy QoS, as it is a Layer-3 switch, and can be report useful stats once QoS is configured.
Cisco has simplified QoS deployment on most newer Catalyst switches with their "AutoQoS" feature. This is an excellent beginning for a foundation in learning and deploying Layer-2 QoS.
The link for deploying a feature called "AutoQoS" on 3750's is shown here:
There are several ways to do what you're trying to do. However, the Avaya equipment software settings will play a factor in some of your choices. Can I assume that no QoS is enabled on your Avaya server, phones, or network switches?
In my organization (Citrix Systems) we had to program our Avaya end-points (servers and phones) to start using layer-2 and layer-3 QoS values on the LAN. Then, we used Cisco's AutoQoS to recognize those values and prioritize them.
By default it appears Avaya uses layer-3 QoS, but not Layer-2 QoS unless that is turned on.
Layer-3 QoS involves "DiffServ" values inside of IP Packets, usually written as "dscp"
DSCP = 46 is the "default" value Cisco's AutoQoS is configured to prioritize at layer-3
Layer-2 QoS involves "Class-of-Service" values inside of IEEE 802.1Q Ethernet frames, usually written as "CoS"
CoS = 5 is the default value Cisco's AutoQoS is configured to prioritize at layer-2.
Note: These values are derived from IETF recommended standards, which get stale, but are still relevant...
You may try the following, but should back this up with researched knowledge to protect your organization from any potential misconfiguration:
Step 1: Deploy "AutoQoS" on your 3750. I won't tell you the commands, because you relly need to read this at a minimum if you ever hope to support it after the fact.
Step 2: On the switch ports that contain any Avaya equipment like phones or servers (or appliances), you may want to use the command:
"mls qos trust dscp" - this will tell the 3750 switch port to "trust" (and prioritize) any dscp values it sees in incoming IP packets.
What effect will this have? Avaya marks IP telephony AUDIO (not signaling) packets with DSCP 46 by default. Cisco's AutoQoS "knows" this value to be voice-related, and gives it priority on the 3750 switch.
Step 3: On the switch port that contains your DSL router, you may also wish to use the command "mls qos trust dscp".
Again, this will give priority to any Avaya voice packets coming in from the WAN.
Step 4: Monitor your results by using the following command on the 3750:
"show mls qos interface statistics"
This will show you columns of numbers for each port. Reading from left to right, you should see a row that begins with the numbers 45 - 49. Column1=45, Column2=46, etc...
When you see the counters increment for Column 2 (DSCP 46) you are on your way...
Time permitting, I may be able to assist you further...best of luck, and if your 3750 is under Cisco's Smartnet coverage, then Cisco TAC will be a powerful ally for you as well.
Regards,
Russ Splain
splainr@bellsouth.net
I may have some helpful info for you on this...
I just completed the rollout of Layer-2 QoS (meaning Cisco Catalyst switches only) on a global network, which uses Avaya IP telephony and "3750's" as you've mentioned.
The 3750 is an excellent device on which to learn and deploy QoS, as it is a Layer-3 switch, and can be report useful stats once QoS is configured.
Cisco has simplified QoS deployment on most newer Catalyst switches with their "AutoQoS" feature. This is an excellent beginning for a foundation in learning and deploying Layer-2 QoS.
The link for deploying a feature called "AutoQoS" on 3750's is shown here:
There are several ways to do what you're trying to do. However, the Avaya equipment software settings will play a factor in some of your choices. Can I assume that no QoS is enabled on your Avaya server, phones, or network switches?
In my organization (Citrix Systems) we had to program our Avaya end-points (servers and phones) to start using layer-2 and layer-3 QoS values on the LAN. Then, we used Cisco's AutoQoS to recognize those values and prioritize them.
By default it appears Avaya uses layer-3 QoS, but not Layer-2 QoS unless that is turned on.
Layer-3 QoS involves "DiffServ" values inside of IP Packets, usually written as "dscp"
DSCP = 46 is the "default" value Cisco's AutoQoS is configured to prioritize at layer-3
Layer-2 QoS involves "Class-of-Service" values inside of IEEE 802.1Q Ethernet frames, usually written as "CoS"
CoS = 5 is the default value Cisco's AutoQoS is configured to prioritize at layer-2.
Note: These values are derived from IETF recommended standards, which get stale, but are still relevant...
You may try the following, but should back this up with researched knowledge to protect your organization from any potential misconfiguration:
Step 1: Deploy "AutoQoS" on your 3750. I won't tell you the commands, because you relly need to read this at a minimum if you ever hope to support it after the fact.
Step 2: On the switch ports that contain any Avaya equipment like phones or servers (or appliances), you may want to use the command:
"mls qos trust dscp" - this will tell the 3750 switch port to "trust" (and prioritize) any dscp values it sees in incoming IP packets.
What effect will this have? Avaya marks IP telephony AUDIO (not signaling) packets with DSCP 46 by default. Cisco's AutoQoS "knows" this value to be voice-related, and gives it priority on the 3750 switch.
Step 3: On the switch port that contains your DSL router, you may also wish to use the command "mls qos trust dscp".
Again, this will give priority to any Avaya voice packets coming in from the WAN.
Step 4: Monitor your results by using the following command on the 3750:
"show mls qos interface statistics"
This will show you columns of numbers for each port. Reading from left to right, you should see a row that begins with the numbers 45 - 49. Column1=45, Column2=46, etc...
When you see the counters increment for Column 2 (DSCP 46) you are on your way...
Time permitting, I may be able to assist you further...best of luck, and if your 3750 is under Cisco's Smartnet coverage, then Cisco TAC will be a powerful ally for you as well.
Regards,
Russ Splain
splainr@bellsouth.net
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