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RED/WRED

Answered Question
Jan 21st, 2014
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Hi everybody.



RED/WRED randomly pick packets and dropped when the threshold are reached. My question is : Is it  always a TCP packet or it could any packet?



Thanks

Correct Answer by Reza Sharifi about 3 years 7 months ago

Hi Sarah,


So, apparently RED and WRED is more effective with TCP connections according to this document;


WRED is useful with adaptive traffic such as TCP/IP. With TCP, dropped packets indicate congestion, so the packet source will reduce its transmission rate. With other protocols, packet sources may not respond or may resend dropped packets at the same rate. Thus, dropping packets does not decrease congestion.


here is the link:


http://www.cisco.com/en/US/docs/ios/12_2/qos/configuration/guide/qcfwred_ps1835_TSD_Products_Configuration_Guide_Chapter.html


HTH

Reza

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Correct Answer
Reza Sharifi Tue, 01/21/2014 - 19:58
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    2017 LAN

Hi Sarah,


So, apparently RED and WRED is more effective with TCP connections according to this document;


WRED is useful with adaptive traffic such as TCP/IP. With TCP, dropped packets indicate congestion, so the packet source will reduce its transmission rate. With other protocols, packet sources may not respond or may resend dropped packets at the same rate. Thus, dropping packets does not decrease congestion.


here is the link:


http://www.cisco.com/en/US/docs/ios/12_2/qos/configuration/guide/qcfwred_ps1835_TSD_Products_Configuration_Guide_Chapter.html


HTH

Reza

sarahr202 Tue, 01/21/2014 - 21:05
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Thanks reza, i understand how red or Wred affect tcp traffic, however i am trying to find if wred or red pick tcp only or any traffic,

Thanks

Joseph W. Doherty Wed, 01/22/2014 - 05:24
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It depends on what traffic you're subjecting to WRED.  I.e. WRED doesn't, by itself, examine "kind" of packet.


For example, WRED will often, by default, apply different min/max limits depending on a packet's ToS.

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