12 votes
Accepted

Does IP provide QoS or not?

IPv4 has the DSCP (formerly ToS) field, and IPv6 has the Traffic Class field. Those are just fields in the IP headers. IP itself does not have any QoS. QoS is implemented by network devices, often ...
Ron Maupin's user avatar
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10 votes
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How to find the client who downloads a big file?

The easy way to do it could be: On your WLC home page you should have something like: You can reset the stat through the gear icon on the top right corner, selecting "Clear Dashboard Data" Then ...
JFL's user avatar
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9 votes
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Is QoS an issue for VOIP calls over the Internet? If not, why not?

VoIP over the public Internet can be a problem, but it usually works good enough, most of the time, although there can be times where it sucks. Most ISPs have extra cost features where they will honor ...
Ron Maupin's user avatar
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9 votes
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Are all 64 DSCP values usable/configurable?

You can use the DSCP values in any way you want on your own network (DSCP values are not honored on the public Internet). You can even make EF be the lowest priority value. You first classify the ...
Ron Maupin's user avatar
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8 votes

Is QoS an issue for VOIP calls over the Internet? If not, why not?

I'm trying to decide whether I should buy SIP trunks from my ISP or a 3rd-party. and... Is QoS an issue for VOIP calls over the Internet? Short answer: End-to-end QoS is NOT offered on the public ...
Mike Pennington's user avatar
8 votes
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What is the difference between Cisco's QoS models and strategies?

What is a strategy and what is a model depends mostly on the words the author likes to use. In this case you could substitute one for the other. Best effort is essentially no QoS. You might say the ...
Ron Trunk's user avatar
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6 votes
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Qos Packet drops

Note that the offered rate is a 30-second average. If your traffic is bursty then you may very well have had a very short burst of over 800000 bps (causing the shaper to kick in) and very little ...
hertitu's user avatar
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6 votes
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Basic Catalyst 3560 Egress Shaping

And now the real question: To shape all unclassified egress traffic to fit into 50 Mbps, can I just enter srr-queue bandwidth shape 0 2 0 0 on the interface in question and be done? It ...
Todd Wilcox's user avatar
  • 1,135
6 votes

What is Class-based WFQ and LLQ?

Fair Queuing share the link in equal capacity among the different flow. Weighted Fair Queuing give allows schedulers to specify, for each flow, which fraction of the capacity will be given. This ...
JFL's user avatar
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6 votes
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Network Control Packets and QoS

The following information is only based on Cisco equipment. 1-Should I do any classification, as a network admin, to separate these protocols' packets? Don't all these protocols label their ...
Cow's user avatar
  • 1,732
6 votes
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QoS policy definition - Cisco guidelines vs reality

If you are using eight classes, then you are probably overthinking it. You want most traffic to be in the default class, protect real-time traffic with a priority class and policing, make sure that ...
Ron Maupin's user avatar
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6 votes
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What's difference between traffic shaper and scheduler?

The authoritative source would be RFC7640 in which you will find the following definition: Traffic scheduling: provides traffic classification within the network device by directing packets to ...
JFL's user avatar
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5 votes
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Applying a queuing service policy

The default-class uses (by default) 50 percent of the available bandwidth. You can reduce that value as part of your policy-map. For example: policy-map type queuing TA-queuing ... class-type ...
Ron Trunk's user avatar
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5 votes
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How does throttling of network traffic work (to limit bandwidth by ISP e.g.)?

This really has nothing to do with TCP, or any other layer-4 protocol. For the most part, this is done simply through policing (dropping) any inbound packets that would exceed the bandwidth limit. ...
Ron Maupin's user avatar
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5 votes
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QoS shaper, shapes traffic without dropping packets?

How does my policy manage to shape traffic to the requested size without dropping packets? ... Tunnel traffic remains 10Mbps and still a few packets in queue but no drops… Your C-class FTP ...
Mike Pennington's user avatar
5 votes
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QoS Policing vs Shaping, why policing

There are cases where the given platform cannot shape at all or not in the required direction. On the (Cisco) platforms I have come across, ingress QoS is usually able to police, but not shape, while ...
Marc 'netztier' Luethi's user avatar
5 votes
Accepted

Cisco QoS algorithm - classification process

The interface A is configured with a service policy SP. SP is a policy map, containing 4 class map. So, when a packet arrive in the interface A, switch retrieve the policy map associated. ...
Mike Pennington's user avatar
5 votes

Cisco QoS algorithm - classification process

Classification and marking is separate from performing a policy action based on the marking. IPv4 packet headers have the DSCP (formerly ToS) field, and IPv6 packet headers have an equivalent Traffic ...
Ron Maupin's user avatar
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5 votes

STP packets and QoS

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) ...
Cow's user avatar
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5 votes
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Suggestion for Weights for Weighted Round Robin

14 egress queues seems a bit excessive - most devices I dealt with use 3, 4 (most common), or up to 8 queues. I'd just use four which simplifies things: critical traffic (very low-bandwidth, critical ...
Zac67's user avatar
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5 votes
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Unable to see packet drops on tunnels

The bandwidth command is simply a label for things like routing protocols and QoS. It does not change the bandwidth on the interface. If you want it to drop packets above 10 Mbps, you can create a ...
Ron Maupin's user avatar
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5 votes
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How does policing prevent LLQ queue starvation? (QoS)

How exactly does Policing prevent the queue starvation problem? You adjust the policing threshold so that the input rate to the priority queue is less than the output rate.
Ron Trunk's user avatar
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4 votes
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Jumbo frame on Nexus 5k

Yes you can, you just have to classify the traffic. Here is an example where we classify iSCSI into its own class. The class-default class will match any other traffic. class-map type qos match-all ...
John K.'s user avatar
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4 votes

How ISP track the individual subscriber data download and falling back to lower mbps?

So, there are a few different methods that can be used to achieve this, but I'll stick to the ones I am familiar with. In a PPPoE(oA) environment (e.g.: xDSL), each subscriber is tracked via a ...
Benjamin Dale's user avatar
4 votes
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Access and uplinks ports QoS Queuing model

The model is roughly the same, but the marking is different (swap source and destination), and you may allocate queues differently due to higher bandwidth.
Ron Trunk's user avatar
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4 votes
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QoS on 2960X does not seem to have an impact

As already commented, QoS can only shape your traffic in case of congestion - it can prioritize some traffic before other but it can't make your network faster. The only way to reduce idle latency is ...
Zac67's user avatar
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4 votes
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Understand DSCP and Precedence Values in Ipv4 or Ipv6 packet

The IPv4 DSCP (IPv6 Traffic Flow) packet header field can be used to mark packets for later treatment in network congestion. There are recommendations and guidelines for interpreting these values a ...
Ron Maupin's user avatar
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4 votes

How did ATM switches that were implemented in a core of IP network improve QoS and higher data rate?

ATM (which is all but obsolete today) provided classes of service that guaranteed bandwidth resources. That feature has been replaced by classes of service in IP (using DSCP markings) that can be ...
Ron Trunk's user avatar
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