Questions tagged [qos]

For questions about Quality Of Service (QoS); all aspects of providing differential service to packets based on TOS, DSCP, or other information.

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26 views

How to determine root-cause of network latency and disconnections [closed]

I am connected to internet through ADSL. It happens frequently that i see very sharp latency in internet speed and even sometimes i am not able to browse. When calling the ISP they confirm they do not ...
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46 views

Cisco Catalyst QoS queuing model

How Cisco Hardware queuing model (like 1p7q4t for Cat6800) are related to traffic classes (class-map) ? How assign the X traffic class to Y hardware queue ? Also, if only 6 classes are configured, ...
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16 views

Yealink T22p Quality Issue

We have around 7 Yealink T22p. Phone quality is good when only one phone is being used. If there are more than two phones are being used at the same time, one of them breaks up a lot but it breaks ...
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55 views

Suggestion for Weights for Weighted Round Robin

I have looked over the book "End-to-End QoS Network Design" by Tim Szigeti et al. and RFC4594. The RFC proposes 14 Service class: I have a switch with simple QoS features. It has 14 egress queues on ...
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54 views

STP packets and QoS

Routing protocol packets are IP packets and therfore they could have different DSCP values to have different priorities (which is implemented by QoS policy) during congestion. How about non-IP packets?...
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46 views

Network Control Packets and QoS

In RFC 4594, titled as "Configuration Guidelines for DiffServ Service Classes", it is suggested that network control packets should be tagged by DSCP 48 (CS6). Protocols like OSPF, EIGRP, ISIS and so ...
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1answer
62 views

Cisco nexus 9396PX TX output discard on 40G interface without link congestion

We have cisco nexus 9396PX with N9K-M12PQ module (12x40G Interface), We have 8x10G L3 LACP bonded connectivity with our ISP and so far so good no issue at all. but recently we migrated that LACP LAg ...
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18 views

Can QoS provide a benefit after data has gone through other unmanaged switches first? [duplicate]

Details about the devices We have a 24 port NETGEAR managed POE switch that has QoS capabilities. We have the following unmanaged switches, 24 port Cisco POE, 48 port Cisco, 48 port NETGEAR, and 24 ...
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85 views

Do unmanaged switches honour QoS priorities set by managed switches?

Details about the devices We have a 24 port NETGEAR managed POE switch that has QoS capabilities. We also have the following unmanaged switches, 24 port Cisco POE, 48 port Cisco, 48 port NETGEAR, ...
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2answers
125 views

Trust dscp command missing on cisco 3850

We have an incoming QoS configuration on our 2960X switches like this: class-map match-any QOS_GL_TRUST match ip dscp 8 16 24 32 46 class-map match-any QOS_GL_CITRIX match access-group name ...
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52 views

QoS - Add DSCP EF tag with L2 switches?

Here is the topology that I have: Phone => (access port) L2 Switch (trunk) => Router My goal here is to add an EF tag to the packets coming from my phones. Basically, if a packet comes in being in ...
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15 views

Why in DRR (Deficit Round Robin) is the Deficit Counter set to 0 when the list of packets for a flow gets empty?

I'm studying DRR scheduling algorithm (https://www2.cs.duke.edu/courses/cps214/spring09/papers/drr.pdf) but I don't understand why the deficit counter is always reset to 0 when the list of a flow get ...
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63 views

C3PL working order

It is very hard to find information on this topic. I would like to know: If traffic has a hit inside a class-map, is it immediately forwarded or does it get checked against all remaining match ...
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39 views

Fair-queueing every class within CBWFQ

My question is similar to: What is benefit of using CBWFQ with fair-queue statement Given this policy-map (without class-maps) configuration: policy-map test class DSCP30 bandwidth percent 20 ...
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36 views

qos inside vpn, possible or not ? I read yes and no

I am wondering if possible to do QOS (or similar action) inside vpn tunnel to a cloud server. the goal is to reserved bandwith for voip traffic. I read that you can with GRE and other people said, ...
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1answer
124 views

Cisco QoS SRR Share & Shape impact

I am working on understanding the impact of using shaping and sharing with the SRR scheduler. Given these 2 commands on an interface: switch(config-if)#srr-queue bandwidth share 40 20 30 20 switch(...
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27 views

QoS Classification and Drop Rate

Sorry if i sound completely senseless, In CBWFQ, q1) Does WRED only make sense if there is more than 1 dscp marking in a queue ? q2) if traffic_typeA is to be handle with higher priority then ...
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60 views

QoS on 2960X does not seem to have an impact

We have some issues with Dect stations that have a very high requirement in regards of delay. Communication between 2 devices should not exceed 500 microseconds (0.5ms). We decided to test some ...
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42 views

CISCO Tc Bc and CIR units

Are the units in these formulas correct? Tc (seconds) = Bc (bits) / CIR (bits per second) Tc (milliseconds) = Tc (seconds) * 1000 Bc (bits) = Tc (seconds) * CIR (bits per second) CIR (bits per second)...
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27 views

Access and uplinks ports QoS Queuing model

On an access switch, does the uplinks egress QoS Queuing model (multiple traffic classes and bandwidth reservation), should be different than the access ports egress Queuing model ? Is there a sense ...
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45 views

what is the difference between OpenFlow queue and 802.1p

I was reading about queues and I came across OpenFlow Queues and IEEE 802.1p I would like to know what are the main differences between them, and how they treat the traffic. In other words how they ...
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32 views

Is WRED configured for TCP traffic only?

I am looking out for a practical usage of WRED. After reading/searching I found that it is more suitable for TCP traffic. When the queue is full, all the TCP session at that time will start with slow ...
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196 views

How to block youtube url on a cisco router

How can i block youtube on a cisco router? I have already used class map as seen below class-map match-any url-block-class match protocol http host "*youtube*" ! policy-map block-class policy-map ...
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31 views

What is the difference between Custom Queuing and Weighted Fair Queuing?

I understand that both mechanisms send traffic in a round-robin fashion, and the traffic is sent proportionally to their weight based on the ToS of the traffic. However, I don't understand the ...
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149 views

Cisco QoS trust and cos-dscp dscp-cos Mapping behaviors

Regarding our current Cisco QoS implementation, to get a deeper understanding I would have some questions I read this: https://www.cisco.com/c/en/us/support/docs/wireless-mobility/voice-over-wireless-...
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81 views

QoS color aware and color blindness?

QoS - Color Aware and Color Blind mode. Is color - red, yellow and green is a kind of analogy for violate, exceed and conform traffic rate. If so, whey did they come for the colors here. I mean ...
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2answers
230 views

QoS for OSPF, VOICE and CRITICAL Traffic

I plan to implement the QoS policy below. The target is to garantee bandwidth to VOICE and CRITICAL traffic. It should be 1/3 for Voice and Video, 1/3 for Business Critical traffic, 1/3 for all the ...
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83 views

Cisco ISR - Police & burst

We have a Cisco C2900 ISR here, with the following configured: policy-map XX_4M _IN police rate 4000000 burst 400000 conform-action transmit exceed-action drop The policy-map is applied on an ...
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50 views

traffic shaping

I need some clarifying on that issue (little bit rusty on that) Assuming I have some limitation on the BW of 1Mb. What will happen then there is incoming traffic of 1.5Mb for 10 sec - some of the ...
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51 views

How color is encoded in the DS field/ToS IPv4 - QoS?

The RFC 2698 says - "The color is coded in the DS field [RFC2474] of the packet in a PHB specific manner". I am trying to understand how color is encoded like in the IPv4 header - in the TOS field ...
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196 views

QoS: priority-queue out

I'm trying to understand the priority-queue out command configured on an interface. Based on what I have read, here is what it does : the Priority Queue (Queue 1) on the switch will be emptied before ...
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101 views

Cisco QoS Queuing models

I would have a question about the Cisco Queuing models. For example, when we speak about 1p7q3t, or 2p6q3t, or others models, does it from hardware or software considerations ? If it's hardware, if ...
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39 views

I limit the port INGRESS but get packet loss

I use the limit speed method to limit the Juniper Switch port EGRESS and INGRESS speed. but after I added the INGRESS filter to my port, there will loss packets on the switch every port. anybody ...
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1answer
321 views

QOS police vs bandwidth - is this configuration wrong?

I understand bandwidth in QOS is use to guarantee a minimum bandwidth I understand police in QOS is to set a limit to the maximum bandwidth. class test_out police **1608000** 50000 100000 conform-...
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2answers
128 views

Hierarchical QoS

As I understood, the main difference between H-QoS and QoS is the level of category granularity, in which we could apply different QoS tools and policies. For example in simple QoS, just ...
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1answer
104 views

DSCP re-marking on Cisco Switch

I've followed the commands in this post: DSCP trust boundary policy-map MARKDOWN class class-default set dscp ef Interface Config: interface gig 0/1 service-policy input MARKDOWN The ...
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1answer
73 views

Is Cisco SG300-10PP & QoS appropriate to share bandwidth?

We're going to let some empty space in our office building soon. The potential client needs an internet connection for their systems (including VoIP).For ourselves we have a resilient ethernet setup, ...
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52 views

Latency in Network [closed]

My company uses trading application where latency is utmost important. I have few ideas but really dont know how to implement. Like I want to know 1) How can I Prioritize applications by 802.1q tag. ...
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507 views

Cisco 3850 Output Drops IOS XE Everest Version 16.6.1

We have a MPLS link connected to our 3850 with voice traffic, our interface have 1Gbps and the link is limited to 200Mbps. Our interface shows output drops, and the client device shows overruns. What ...
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1answer
662 views

Quality of Service: Questions about input and output service policies prioritizing the same traffic

This question/lab was created with Cisco networking hardware. I have asked this question else where with no responses. I am new to QoS, but I have spent the last few days researching and I've ...
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1answer
1k views

Default QoS Behavior on Catalyst 3650/3850 Running IOS XE 16.3.6

I am trying to better understand the default queuing behavior on Catalyst 3650/3860 running IOS XE 16.3.6 Denali. Is QoS enabled globally by default? Coming from working with Catalyst 2960X on IOS 15 ...
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1answer
56 views

HP 6120X Blade switch QoS

I just got access of blade center and i was looking at configuration of switch which is following. I can see switch has already QoS configured, I am not very expert in QoS so trying to understand ...
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46 views

traffic of AF41 marking under interface

I have used port-queue commands most of the time to check traffic status under BE, EF, AF4. But I haven't found command to check for AF41 to AF42 on Huawei VRP or cisco IOS. How can check traffic of ...
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53 views

Service Policy CISCO 7606 not work [closed]

I have bandwidth control in cisco 7606 but the same is not limiting my clients. I checked the settings and did not identify an error. This box is 1 replacement for 1 old 7606 model. Is it necessary to ...
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154 views

Simple Token Bucket - Policing - Terms - CIR, CBS

I have gone through token bucket algorithm. However, I am struggling to apply this knowledge into the real devices like CISCO, etc. So, for QoS policing, interface meter. I am trying to understand ...
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48 views

QOS - the need for it and verifying it

Just some straightforward questions, hope gurus here can shed some light 1) show int - output queue -> this is the hardware queue (tx-ring) or this is the software queue ? if I see drop, this means ...
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1answer
83 views

Cisco Unity Connection guest, ESXi host, IP phones, vlan, subnet, ip addresses, qos

I have setup: VLAN 1 and subnet 192.168.1.0/24 for data VLAN 100 and subnet 192.168.100.0/24 for voice IP phones get their IP via DHCP on the subnet 192.168.100.0/24 all other IP devices get their IP ...
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30 views

Policy Map issue on c6848x 15.2(02)SY

I have a problem creating traffic shaping on c6848x. I need to set shaping on output interface to limit and shape traffic to 100 MBs. So far I did this: class-map match-any 100MB-OUT match any ...
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1answer
78 views

QoS: Configuration failed. deny is not supported

object-group network ip-google 8.8.4.0 255.255.255.0 8.8.8.0 255.255.255.0 8.34.208.0 255.255.240.0 8.35.192.0 255.255.240.0 23.236.48.0 255.255.240.0 23.251.128.0 255....
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2answers
294 views

Match DSCP in IPv4/IPv6 packets is not supported for this interface

i have cisco asr 903 (ios xe) i need to limitation Traffic for google-traffic this my configuration ip access-list extended ip-google-traffic permit ip 8.8.4.0 0.0.0.255 any permit ip 8.8.8.0 0.0....