[Spread-users] High retrans rate

Martin Decker mdecker77 at aol.com
Wed Oct 2 06:15:55 EDT 2002


Hi,

I am experiencing a very high retransmission rate when testing spflooder with 
1000 byte messages.

sent pack:    1001      recv pack :       6     retrans    :    1135

We are evaluating Spread 3.17 in a setup with 1 sender and 2 receivers in the 
same LAN. We use a Catalyst 5500 Switch with a static multicast address. The 
spread conf looks like:


Spread_Segment 226.0.0.6:4803 {
    dev901	195.232.84.170
    dev911	195.232.84.188
    dev912	195.232.84.189
}

I tested with:
dev912$  ./bin/spflooder -m 1000 -b 1000 -ro
dev911$  ./bin/spflooder -m 1000 -b 1000 -ro
dev901$  ./bin/spflooder -m 1000 -b 1000 -wo

Interesting seems that only one receiver (dev912) needed retrans.

============================
Status at dev901 V 3.17. 0 (state 1, gstate 1) after 29 seconds :
Membership  :  3  procs in 1 segments, leader is dev901.lab.aol.de
rounds   :     516      tok_hurry :      12     memb change:       1
sent pack:    1001      recv pack :       6     retrans    :    1135
u retrans:       8      s retrans :    1127     b retrans  :       0
My_aru   :    1008      Aru       :    1008     Highest seq:    1008
Sessions :       0      Groups    :       0     Window     :      60
Deliver M:    1000      Deliver Pk:    1008     Pers Window:      15
Delta Mes:    1000      Delta Pack:    1005     Delta sec  :      13
==================================

Monitor> 
============================
Status at dev912 V 3.17. 0 (state 1, gstate 1) after 26 seconds :
Membership  :  3  procs in 1 segments, leader is dev901.lab.aol.de
rounds   :     515      tok_hurry :      12     memb change:       1
sent pack:       3      recv pack :    1004     retrans    :     156
u retrans:     156      s retrans :       0     b retrans  :       0
My_aru   :    1008      Aru       :    1008     Highest seq:    1008
Sessions :       0      Groups    :       0     Window     :      60
Deliver M:    1000      Deliver Pk:    1008     Pers Window:      15
Delta Mes:       0      Delta Pack:       0     Delta sec  :      -3
==================================

Monitor> 
============================
Status at dev911 V 3.17. 0 (state 1, gstate 1) after 23 seconds :
Membership  :  3  procs in 1 segments, leader is dev901.lab.aol.de
rounds   :     515      tok_hurry :      12     memb change:       1
sent pack:       3      recv pack :    1433     retrans    :       0
u retrans:       0      s retrans :       0     b retrans  :       0
My_aru   :    1008      Aru       :    1008     Highest seq:    1008
Sessions :       0      Groups    :       0     Window     :      60
Deliver M:    1000      Deliver Pk:    1008     Pers Window:      15
Delta Mes:       0      Delta Pack:       0     Delta sec  :      -3
==================================


Changing the parameters of spflooder to "-m 100000 -b 100"  resulted in an 
acceptable retrans rate:

============================
Status at dev912.lab.aol.de V 3.17. 0 (state 1, gstate 1) after 173 seconds :
Membership  :  3  procs in 1 segments, leader is dev901.lab.aol.de
rounds   :   33123      tok_hurry :      45     memb change:       2
sent pack:       4      recv pack :   38617     retrans    :     122
u retrans:     122      s retrans :       0     b retrans  :       0
My_aru   :  100008      Aru       :  100008     Highest seq:  100008
Sessions :       0      Groups    :       0     Window     :      60
Deliver M:  100000      Deliver Pk:  100010     Pers Window:      15
Delta Mes:       0      Delta Pack:       0     Delta sec  :      15
==================================

Monitor> 
============================
Status at dev901.lab.aol.de V 3.17. 0 (state 1, gstate 1) after 177 seconds :
Membership  :  3  procs in 1 segments, leader is dev901.lab.aol.de
rounds   :   33125      tok_hurry :      45     memb change:       2
sent pack:   37103      recv pack :       7     retrans    :    2153
u retrans:       0      s retrans :    2153     b retrans  :       0
My_aru   :  100008      Aru       :  100008     Highest seq:  100008
Sessions :       0      Groups    :       0     Window     :      60
Deliver M:  100000      Deliver Pk:  100010     Pers Window:      15
Delta Mes:       0      Delta Pack:       0     Delta sec  :       4
==================================

Monitor> 
============================
Status at dev911.lab.aol.de V 3.17. 0 (state 1, gstate 1) after 168 seconds :
Membership  :  3  procs in 1 segments, leader is dev901.lab.aol.de
rounds   :   33014      tok_hurry :      41     memb change:       1
sent pack:       3      recv pack :   38745     retrans    :       0
u retrans:       0      s retrans :       0     b retrans  :       0
My_aru   :  100008      Aru       :  100008     Highest seq:  100008
Sessions :       0      Groups    :       0     Window     :      60
Deliver M:  100000      Deliver Pk:  100008     Pers Window:      15
Delta Mes:       0      Delta Pack:       0     Delta sec  :      -9


Can you confirm such a behaviour?

Martin


-- 
// Martin Decker, Systems Engineer, Data Center Operations     //
// AOL Germany, Dingolfinger-Str. 2-4, D-81673 Munich, Germany //
// AIM: mdecker77 mail: mdecker77 at aol.com ICQ: 15620821        //
// Phone:+49.8966572214                                        //





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