[Udpcast] switch_issue_using_udpcast

Stefan Jaeckel stefan.jaeckel at wiwi.uni-halle.de
Wed Apr 18 14:31:19 CEST 2007


Hello everybody,

udpcast works very fine on all of my switches, without one. udpcast worked 
also always very fine on that "special" switch (cisco 3560), but only on the 
last time it works not. That means: some time earlier, it worked on that 
switch without any problems , but only on last time it works not. i am only  
a "switchuser", that means that i am not be able to administrate the 
switches. the administrator of the switches said, that all switches have got 
the same configuration.

let me illustrate the network: all workgroup-switches (cisco 2950, 3560 - 
which being used with udpcast) are connected (cascaded) to a cisco 6509 
switching-factory with fibre-channel cables. all these components constitute 
a layer 2 network (ethernet). behind the cisco 6509 stands a cisco router 
(the next layer 3 instance, also connected with fibre channel, i don't know 
the type of this router), which manages the network- routing-protocolls, that 
means it should be also interesting for udpcast mc-routing. 

udpcast does not work on the one cisco 3560. if i use 2 nodes (1 sender , 1 
receiver -- unicast) on that switch it works very well, but with more than 2 
reciever-nodes (multicast) it doesn't work.  every modern cisco switch has 
got a so called "Multicast Forwarding Table" which binds all multicast ports 
(all systems from the "udp-receiver/sender-Multicastgroup" ) via 
igmp-snooping (some thing that can be done from the switch from layer 3) on 
one "Multicast-Mac-Address". this Multicast-Mac-Address would be anounced 
through the cisco switching-factory 6509 until the next cisco-router (layer 3 
instance) is reached. now the udp-sender establishes a connection to this 
MC-group (mac-adresses, binded ports on the switch) and begins to send the 
multcast-data. now the clients do not answer -- i think: maybe, it is a 
broadcast issue on that switch (vlan -- configuration), the udp-sender needs 
a message that a mc-packet is arrived correctly to the receiver (broadcast 
control sender<-->receiver from the program itself can't work correctly). the 
udp-reciever stalles and the sender prints all the timouts from the 
receivers) -- could this be the issue here? Or the routing itself on the next 
layer 3 instance -- i mean, that the layer 3 could not route the mc-pakets to 
the given mc-adress? or the "Multicast Forwarding Table" can only register 1 
port (receiver) for multicasting?

Here is the output from the sender:

(two receivers, it works not):

Udp-sender 2003-08-31
Using mcast address 237.48.205.71
UDP sender for (stdin) at 141.48.205.71 on eth0
Broadcasting control to 141.48.205.255
New connection from 141.48.205.132  (#0) 00000019
Ready. Press any key to start sending data.
New connection from 141.48.205.131  (#1) 00000019
Ready. Press any key to start sending data.
Starting transfer: 00000019
bytes=        570 752 re-xmits=000000 (  0.0%) slice=0056  73 709 551 615 -   
1
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815
Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=7815

---------------------------------------------------------------------------

(one receiver, it works):

Udp-sender 2003-08-31
Using mcast address 237.48.205.71
UDP sender for (stdin) at 141.48.205.71 on eth0
Broadcasting control to 141.48.205.255
New connection from 141.48.205.131  (#0) 00000019
Ready. Press any key to start sending data.
Starting transfer: 00000019
bytes=     88 042 864 re-xmits=000000 (  0.0%) slice=0056  73 709 551 615 -   
0
------------------------------------------------------------------------------------

I hope someone can help me out or give me a hint -- and sorry for my bad 
english!

Best Greatings

Stefan J├Ąckel





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