BTW, I saw UDP souce nodes dropping packets at their ifq_'s, but I don't understand why! I set the packet-generation speed of the UDP sources as exactly the same as the LAN bandwidth, and the link between node0 and node1 has enough bandwidth for both direction packets.
Any comments are welcome!
Thanks,
Huiwen
-----Original Message-----
From: Li, Huiwen [SC1:106:EXCH]
Sent: Wednesday, February 02, 2000 11:38 AM
To: '[email protected]'
Subject: Urgent!
Hi,
I have a question about monitoring ifq_ at a LAN. I modified the code in vlan.tcl so that it can monitor the ifq_, when I use 802_3 MAC at 100 source nodes.
The topology is as follows. Each source node will form a LAN with node 0, while node0 is using DRR to schedule the packets to node1. The traffic source are 50 UDP one-way flows from snode(i) to dnode(i) (0<=i<50)and 50 TCP one-way flows from snode(i) to dnode(i) (50<=i<100).
snode(0)�������������������������������������������������� dnode(0)
������������� \�������������������������������������������� /
snode(1) ---� node 0 ------node1---- node2 ----- dnode(1)
�������������� /������������������������������������������� \
snode(99)������������������������������������������������� dnode(99)
I could see the throughput decrease for both UDP and TCP dramatically, but I could see no drops in ifq_'s! This is extremely strange for UDP flows, because there will be no ACK's for UDP flows, which means no contention at all for UDP source. I am wondering if there are other places that LANs could possibly drop packets except ifq_? I also change the parameters for 802_3 to fit for 100Mbps Ethernet.
Please give me some suggestions. Thanks in advance!
Huiwen