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18

QoS is an umbrella term which covers the use of features such as policing, shaping, traffic classification, and advanced queuing mechanisms. CoS is a form of QoS limited to layer-2 Ethernet and it uses 3-bits (8 values) of the 802.1Q tag to differentiate your traffic. Therefore no trunking, no CoS. DSCP is the most commonly acted upon value at layer-3 and ...


17

Class of Service is a layer 2 identifier, usually in conjunction with an 802.1q tag (You shouldn't see CoS referenced on an access port, only a trunk port). DiffServ would be the corresponding identifier on a layer 3 link. Quality of Service is a superset of both controlling how both layer 2 and layer 3 links classify, police, and queue traffic on ...


7

Can you provide some more information on the equipment used and how much bandwidth you have? Will your voice equipment mark packets itself or do you need to take care of it? Usually CoS 5 and/or DSCP EF is used to carry voice payload. Voice should be sent in some form of LLQ (Low Latency Queue). If you give us some more specifics we could help with ...


6

In the Juniper world they are more interchangeable. As all QoS config is done under the class of service stanza of the config. An example of the config is: class-of-service { forwarding-classes { queue 0 assured-forwarding; queue 1 best-effort; queue 2 expedited-forwarding; } interfaces { ge-0/0/3 { ...


6

CoS operates on Layer 2, whereas QoS operates on Layer 3. CoS is a means of adding a priority to the VLAN header that can later me interpreted by QoS mechanisms to handle the traffic accordingly. A real world example might be a VoIP VLAN on a network, which would usually be marked with a CoS flag as CS7. Routers QoS engines can then interpret that and ...


6

If my memory serves, the older Procurve switches used to accept and forward any CoS/DSCP markings they received. You couldn't modify them unless you were on a 5400xl or better switch. It looks like the 2520 and the 3800 allow you to modify whether or not you're using CoS or DiffServ TOS for classification. The top level command you want is qos type-of-...


6

Per port, not aggregate. Schedulers are not global, rather per interface queue.


5

There's an excellent post by a Cisco employee on Cisco support forums covering this: The QoS value is not part of BPDU frame, but an internal value assigned on the RBUS (assuming 6500 platform) for BPDU frames. BPDUs are marked with BPDU bit in the code and treated differently -- it always gets to the high priority queue (ingress & egress) on ...


5

You should consider policing since your concern is that they don't get more bandwidth than they have been allotted. This will give you a hard limit. Your shaping in this instance is just ensuring that 31457280 goes into the BE forwarding-class, not that they can't get more bandwidth than 31457280.


5

The HP ProCurve switches can have 802.1p CoS Priorities or DSCP Policies set, honored, changed or honored with new priority. By default, Quality of Service is ENABLED and operates based on 802.1p settings in the packet. Classification is configured primarily on a global basis; but can be configured by VLAN and port. Marking is configured primarily on a ...


4

QoS (Quality of Service) is a set of measures intended to provide guarantees not previously provided on packet switched networks. These are used for traffic shaping and to try to get quality guarantees hopefully in some cases approximating circuit-switched protocols over packet switched networks. It is significantly more complex than this in implementation ...


3

Does WRED only make sense if there is more than 1 dscp marking in a queue ? Not really. The point of Weighted RED is to assign different weights to different traffic classes. Doesn't make much sense if you only have one class. What is the difference between 1 big queue, with higher drop rate for lower priority traffic vs. 2 different queues, with 1 ...


3

Packet classification occurs when the packet enters the router. You're trying to apply it on the forwarding table. That's not supported. The Juniper documentation shows the packet flow in the router: Packet flow in MX Routers So try to apply the policy on the input interface like so: set interfaces ge-x/x/x.x family inet policer input MARK-POLICY-1 ...


2

You're going to want a CIR that matches closely with what the bit rate of your "TDM circuit" will be, and a very small CBS (if any at all). A substantial CBS has the potential to introduce FDV because there's some overhead/ability to burst - you want to avoid this. You normally don't have bursts with TDM traffic, but you do with Ethernet, and you don't want ...


2

QoS mechanisms only come into effect when there is congestion on the link. If you have a 20M circuit but connected to a 1G interface, your device will never recognize the congestion because the traffic never reaches 1G. You need to implement inbound policing and outbound traffic shaping at your CIR (commited information rate) of your circuit, which would ...


2

If the clasification isn't available on the switch model, then you need to look at something like ACL-based QoS classification (Layers 2, 3, and 4) so that you can mark what traffic, by IP address range for example and tell the hardware how you want to prioritise the traffic with mappings. CoS is for traffic that is layer 2 only. If you need to prioritise ...


2

i find a success method to policy a traffic of Specify ip's or else on CISCO ASR 903 IOS XE 3.18S for example i have ip's 74.0.0.0/8 for some serivce (Like google) 1-subnet a full range from 1.0.0.0/8 to 255.0.0.0/8 and Cust your ip('s) you want enter link description here 2-now you have two range 1.0.0.0/8 2.0.0.0/7 4.0.0.0/6 8.0.0.0/5 16.0....


1

More than likely, packets from the phone have the correct DSCP values: EF for the data, and something like AF31 for the control traffic (you really do not want the control traffic marked as EF). Your switch will change the traffic to BE unless you use the mls qos trust dscp interface command. Yes, you can set DSCP values on the packets with that switch. It ...


1

So I just came up with a hideous hack that gives the desired result: firewall { family inet { filter DSCP-CLASSIFIER { term MATCH-EF { from { dscp ef; } then { forwarding-class VOICE-FC; accept; } } ...


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