I have a Cisco small business switch and I am wondering what I will gain (or lose) by enabling "TCP congestion avoidance". I read the definition of it but how does one know when one should use it?
I have problem with oracle solaris 10 running on oracle sparc T4-2 server.
Os information: 5.10 Generic_150400-03 sun4v sparc sun4v
Output from tcpstat.d script
TCP bytes: out outRetrans in inDup inUnorder
6833763 7300 98884 0... (2 Replies)
I have a client with a meshed Cisco backbone.
6500's on top, Nexus 7000 in the middle and 4500's in bottom.
Solaris 10 servers connected to the 4500's backing up to a RedHat Linux backup server connected to the Nexus 7000's. The traffic is routed from 4500 --> Nexus 7000 --> 6500 --> Nexus 7000... (3 Replies)
I have noticed that the initial congestion window in my traces is 8920bytes~=6*1448. rfc3390 states the initial cwand should be max 4000 bytes(around 3*1448).
At first i thought it might be because i'm running my server on mac os x, so apple might have modified the tcp stack. Therefore I tried... (2 Replies)
I was looking at differnt types of TCP Congestion Avoidance algorithms and realized that they are almost all tailored toward "high speed networks with high latency" (aka. LFN)
Anybody know of a Congestion Avoidance algorithm used in low-latency networks? (3 Replies)
I am trying to develop a c++ application which will communicate with client through SSL(Not https).We are using self-signed certificates.
I have installed openssl and boost library.
I have tried some boost sample code also and its working.
Boost C++ Libraries -... (2 Replies)
Hello everybody,
It's me again, i need your help!
I was almost finishing a program when it crashed, because of TCP segments with the TCP Options enabled.
I am able to control every field of every packet i receive, except of those using TCP Options. Is there a way to determine if a packet is... (0 Replies)
I have written a TCP/IP client and server program. The client sends a message to the server and then the server sends a file back to the client. The client reads the buffer and stores it another file in the client side.
I need to know what are the various exceptions that I need to handle in... (0 Replies)
Hello ,
I need to convert X.25 packets to IP packets how should i proceed .......... Please help me , regarding this matter or atleast suggest me some material which can be read regarding this .
Bye (2 Replies)
CC_DCTCP(4) BSD Kernel Interfaces Manual CC_DCTCP(4)NAME
cc_dctcp -- DCTCP Congestion Control Algorithm
DESCRIPTION
The DCTCP (data center TCP) congestion control algorithm aims to maximise throughput and minimise latency in data center networks by utilis-
ing the proportion of Explicit Congestion Notification (ECN) marks received from capable hardware as a congestion signal.
DCTCP uses fraction of ECN marked packets to update congestion window. The window reduction ratio is always <= 1/2. Only when all of the
packets are marked, congestion window is halved.
In order to keep the accuracy of the ECN marked fraction, a DCTCP receiver mirrors back incoming (or missing) CE marks by setting (or clear-
ing) ECE marks. This feedback methodology is also adopted when the receiver uses delayed ACK.
The FreeBSD DCTCP implementation includes two minor modifications for the one-sided deployment. Considering the situation that DCTCP is used
as sender and classic ECN is used as receiver, DCTCP sets the CWR flag as the reaction to the ECE flag. In addition, when classic ECN is
used as sender and DCTCP is used as receiver, DCTCP avoids to mirror back ACKs only when the CWR flag is set in the incoming packet.
The other specifications are based on the paper and Internet Draft referenced in the SEE ALSO section below.
MIB Variables
The algorithm exposes the following tunable variables in the net.inet.tcp.cc.dctcp branch of the sysctl(3) MIB:
alpha An initial estimator of the congestion on the link. Default is 0.
dctcp_shift_g
An estimation gain in the alpha calculation. Default is 16.
slowstart
A trigger to halve congestion window after slow start. Default does nothing to halve window.
SEE ALSO cc_chd(4), cc_cubic(4), cc_hd(4), cc_htcp(4), cc_newreno(4), cc_vegas(4), mod_cc(4), tcp(4), mod_cc(9)
Mohammad Alizadeh, Albert Greenberg, David A. Maltz, Jitendra Padhye, Parveen Patel, Balaji Prabhakar, Sudipta Sengupta, and Murari
Sridharan, "Data Center TCP (DCTCP)", ACM SIGCOMM 2010, http://research.microsoft.com/pubs/121386/dctcp-public.pdf, 63-74, July 2010.
Stephen Bensley, Lars Eggert, and Dave Thaler, Microsoft's Datacenter TCP (DCTCP): TCP Congestion Control for Datacenters,
http://tools.ietf.org/html/draft-bensley-tcpm-dctcp-01.
HISTORY
The cc_dctcp congestion control module first appeared in FreeBSD 11.0.
The module was first released in 2014 by Midori Kato studying at Keio University, Japan.
AUTHORS
The cc_dctcp congestion control module and this manual page were written by Midori Kato katoon@sfc.wide.ad.jp and Lars Eggert lars@netapp.com
with help and modifications from Hiren Panchasara hiren@FreeBSD.org
BSD January 12, 2015 BSD
