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"; - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.rutgers.edu
