2022 Developer Survey is open! Take survey.

Hot answers tagged

11 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 ...
user avatar
  • 92.9k
10 votes
Accepted

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 ...
user avatar
  • 18.3k
8 votes
Accepted

ISP edge router configuration

1.Would it be better to setup traffic policing? You're using shaping, which is better in this case. The important thing is to buffer your traffic before sending it to your internet provider. ...
user avatar
8 votes
Accepted

QoS between two sites

I'd recommend migrating from old-school CAR to modern config of CBWFQ. When you do that, you can nest QoS policies together to accomplish more complicated QoS scenarios. Per this Cisco doc, GRE ...
user avatar
  • 1,589
8 votes
Accepted

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 ...
user avatar
  • 92.9k
7 votes
Accepted

Throttling among Data Centers

I am unable to throttle the network by submitting my UDP packets among such links because I worry about packet drops and message losses. At first blush, this sounds more like a design problem with ...
user avatar
7 votes

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

Is QoS an issue for VOIP calls over the Internet? Sometimes. The answer why is related to the extinction of these objects: (for people born after the year 2000, that's a phone booth) Short answer: ...
user avatar
7 votes
Accepted

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 ...
user avatar
  • 62.1k
6 votes

Why doesn't ISPs reset DSCP at the edge before delivering traffic to customers?

I have no practical experience in running CoS/DSCP in ISP networks, but a logical explanation would be that it doesn't make sense to just change fields in a header. Even if I as an intermediate ISP ...
user avatar
  • 15.6k
6 votes
Accepted

QoS on tunnel interface

Have you tried using bandwidth qos-reference? interface Tunnel100 bandwidth 1000 bandwidth qos-reference 1000
user avatar
  • 1,589
6 votes
Accepted

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 ...
user avatar
  • 1,125
6 votes
Accepted

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 ...
user avatar
  • 2,628
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 ...
user avatar
  • 18.3k
6 votes
Accepted

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 ...
user avatar
  • 1,701
6 votes
Accepted

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 ...
user avatar
  • 92.9k
6 votes
Accepted

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 ...
user avatar
  • 18.3k
5 votes

Downstream QoS Feasibility

Now, I've been told that routers with inbound QoS policies are capable of leveraging the TCP congestion avoidance mechanism by dropping ACKs in order to rate-shape inbound traffic. I've never seen ...
user avatar
  • 979
5 votes

QoS for 100mb Circuit

You are correct about the semantics of "bandwidth remaining", but the numbers are a bit different in IOS. IOS only allows QoS to reserve 75% of the bandwidth by default, which can be tuned with max-...
user avatar
5 votes
Accepted

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 ...
user avatar
  • 62.1k
5 votes
Accepted

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. ...
user avatar
  • 92.9k
5 votes
Accepted

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 ...
user avatar
5 votes
Accepted

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 ...
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. ...
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 ...
user avatar
  • 92.9k
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) ...
user avatar
  • 1,701
5 votes
Accepted

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 ...
user avatar
  • 69.6k
5 votes
Accepted

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 ...
user avatar
  • 92.9k
4 votes

Using QoS for HTTP

There is no default dscp value assigned do a HTTP connection by a web browser or web server when connections are initiated by either.
user avatar
  • 5,270
4 votes
Accepted

What is benefit of using CBWFQ with fair-queue statement

To summarize my comments: The benefit of using CBWFQ (class based weighted fair queuing) with the fair-queue statement in the class-default queue (your second example): ... class class-default ...
user avatar
  • 1,626

Only top scored, non community-wiki answers of a minimum length are eligible