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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 ...
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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 ...
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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 ...
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  • 70.5k
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) ...
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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 ...
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3 votes

Why do we need machine learning for QoS classification in SDNs if we have DSCP in IP address for QoS enforcement?

Something has to set the DSCP values. In a traditional network, that comes from either the end user / application, or intervening network hardware. Unless you have significant control of the device/...
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3 votes
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Are there any protocols that DSCP will break?

No protocols will break due to a changed DSCP - how they are treated by upstream devices may change however (traffic may be more likely to be dropped, or aggressively shaped), so this will need to be ...
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3 votes
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QoS Classification and Drop Rate

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 ...
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2 votes
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Match cos is not supported for this interface in the output direction

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....
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2 votes

QoS DSCP AF Class Comparisons

I understand packets are given a Class, 1-4. The higher the Class number, the higher priority that packet gets. I must assume that higher priority means lower chance of being dropped. Is this ...
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1 vote
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How to compare two DSCP ? which one of DSCP 28 and 34 (decimal) has more priority?

There is no way to compare two DSCP values without the specific network QoS configurations. By default, a network device ignores DSCP values, and you must configure QoS on the device. Also remember ...
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  • 93.6k
1 vote

QoS - Add DSCP EF tag with L2 switches?

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 ...
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1 vote
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Fortigate - Routing DSCP tagged packets through different WAN connections

You want to configure up policy based routing. In the gui this is found: Router > Static > Policy Routes. You can do this by using TOS rather than DSCP. WAN1: Incoming interface: LAN Source Address: ...
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1 vote

How packets get differentiated to prioritize?

An application may set the priorities, a switch may set the priorities, a router may set the priorities, or really any device through which your packets travel may set the priorities. Switches may ...
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  • 93.6k

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