Re: EF and BE traffic--unexplained behaviour

[jamal <hadi@cyberus.ca>]

The RED parameters look weird....

On Fri, 4 Aug 2000, Muneyb Minhazuddin wrote:

> 
> Can I ask what type of traffic is it? 
> 
> tcp/udp
> 
> What is the value of the tos byte that you mark the EF traffic with?
> 
> 0xb8/0x2e
> 
> Did you monitor the tcpdump o/p to see if the packets are correctly 
> marked? Use ttt or tcptrace or any other tcpdump analysing package to plot
> the graphs for you.
> 
> I am mystified by your throughput results, you should atleast get 3 to
> 3.5Mpbs for both EF and BE. Can you give me an idea of your network, is it
> just 2 machines connected back to back?
> 
> Cheers
> Muneyb
> 
> On Thu, 3 Aug 2000, Aditya Chugh wrote:
> 
> > Hello Everybody,
> > 
> > I am using my modified version of TTCP (with which I can set the TOS
> > byte of my packets ) to test the throuput and the time taken to traverse
> > 
> > the path from A to B.
> > A and B are both linux machines  connected to the same local LAN. The
> > kernel of A
> > is diffserv enabled,while B has plain vanilla Linux.
> > I run a modified version of "EFCBQ" - the standard script to set the
> > diffserv queues for EF and BE.
> > I assign both EF and BE  4 Mbit of rate ( out of total b/w of 10Mbit ) I
> > 
> > make both the queues "bounded and isolated" ...so they can neither
> > borrow nor lend b/w. The weight assigned to each is 1.  (Script attached
> > 
> > below)
> > 
> > When I send both EF and BE packets simultaneously from A to B , I get EF
> > 
> > b/w about 467 Kb/sec
> > and BE bandwidth about 340Kb/sec---which is OK according to me.
> > When I send only EF packets from A to B the b/w is reduced to around 260
> > 
> > Kb/sec
> > When I send only BE packets the b/w I get is around 336 Kb/sec ?
> > These results are getting repeated consistently. (measurements have been
> > 
> > taken 8-10 times for each case)
> > Isn't this strange ??  How do we explain it ?
> > I am totally stumped ....and  am unable to come up with a coherent
> > explanation
> > 
> > Any help/advice/explanation from you will be sincerely appreciated.
> > Thanks in advance.Please reply soon.
> > regards,
> > Aditya
> > 
> > 
> > 
> > 
> > 
> > The script I used:---
> > 
> > #!/usr/bin/perl
> > #
> > $TC = "/usr/local/iproute2/tc/tc" ;
> > $DEV = "dev eth0";
> > print "$TC qdisc add $DEV handle 1:0 root dsmark indices 64
> > set_tc_index\n";
> > print "$TC filter add $DEV parent 1:0 protocol ip prio 1 tcindex ".
> >   "mask 0xfc shift 2\n";
> > print "$TC qdisc add $DEV parent 1:0 handle 2:0 cbq bandwidth ".
> >  "10Mbit cell 8 avpkt 1000 mpu 64\n";
> > #
> > # EF class
> > #
> > print "$TC class add $DEV parent 2:0 classid 2:1 cbq bandwidth ".
> >  "10Mbit rate 4Mbit avpkt 1000 prio 1 bounded isolated ".
> >  "allot 1514 weight 1 maxburst 4 \n";
> > # packet fifo for EF?
> > print "$TC qdisc add $DEV parent 2:1 pfifo limit 4\n";
> > print "$TC filter add $DEV parent 2:0 protocol ip prio 1 ".
> >    "handle 0x2e tcindex classid 2:1 pass_on\n";
> > #
> > # BE class
> > #
> > print "#BE class(2:2) \n";
> > print "$TC class add $DEV parent 2:0 classid 2:2 cbq bandwidth ".
> >  "10Mbit rate 4Mbit avpkt 1000 prio 7 bounded isolated allot 1514 weight
> > 
> > 1 ".
> >  "maxburst 4  split 2:0 defmap 0xffff \n";
> > print "$TC qdisc add $DEV parent 2:2 red limit 4KB ".
> >    "min 20kBit max 4KB burst 4 avpkt 1000 bandwidth 10Mbit ".
> >    "probability 0.02\n";
> > print "$TC filter add $DEV parent 2:0 protocol ip prio 2 ".
> >    "handle 0 tcindex mask 0 classid 2:2 pass_on\n";
> > 
> > 
> > 
> > 
> 
> _________________________________________________________
> Muneyb Minhazuddin - Telecommunications Research Engineer    
> CSIRO Telecommunication and Industrial Physics                
> Marsfield, NSW, Australia.                                    
>                                                              
> Phone no. : 61 2 9372 4113
> FAX       : 61 2 9372 4490          
> e-mail    : mminhazu@tip.csiro.au  
> Home Page : http://www-networks.tip.csiro.au/~mminhazu
> ---------------------------------------------------------
> 
>