Packet loss when using Load Balancer cbr forwarding method
 Technote (troubleshooting)
 
Problem(Abstract)
When using the cbr forwarding method, Load Balancer must interact with the connection in more than just a simple proxy mode. It must track and convert the sequence and acknowledgement numbers during the initial connection.
 
Cause
When using Dispatcher's cbr forwarding method, Load Balancer must detect key values in the packet payload before choosing a server. Usually the key value is the head of headers in an HTTP request. Until this value is seen, Load Balancer acknowledges the packets received and buffers the data.
 
Resolving the problem
Load Balancer must forward packets in a timely fashion for performance reasons. Generally, the back-end server and Load Balancer are located on a reliable network within close proximity to each other. There is normally a very low rate of packet loss between Load Balancer and the back-end servers. However, if a packet that is buffered by Load Balancer before the key value, is lost when transmitted to the back-end server, it is not (by default) retransmitted and the connection fails.
If you experience packet loss, specify the e xm 37 command option immediately after starting the executor to instruct Load Balancer to ensure guaranteed delivery of these packets.

Important: This option increases CPU usage and should not be used unless packet loss is incurred and there is no other way to make a reliable network between the Load Balancer and the back-end servers.
 
 
Cross Reference information
Segment Product Component Platform Version Edition
Application Servers WebSphere Edge Server Load Balancer AIX, Linux, Solaris, Windows 2000, Windows NT Edge Server 2.0 GA, Edge Server 2.0 NLV, Edge Server 2.0.x
Application Servers Runtimes for Java Technology Java SDK
 
Historical Number
192705
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Edge Component
Operating system(s): Windows
Software version: 5.1
Software edition:
Reference #: 1166339
IBM Group: Software Group
Modified date: Sep 28, 2007