When Resource load is high, why isn't my Cacheflow indicating that Resource load is high for health-check from the redirector?

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Article ID: 167421

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Updated On:

Products

CF-5000 CF-500

Issue/Introduction

The most likely reason is because the "redirector-ips" setting is not configured on the Cacheflow. It is recommended to configure the CacheFlow appliance with the identity of the device(s) that redirect traffic to it (L4/7 switches or PBR routers). This information is used to ensure that health checks from the switches or routers are properly handled and do not incorrectly fail when the CacheFlow implements certain capacity-control mechanisms under heavy load.

Use the following CacheFlow commands to configure the IP address(es) of the redirector device(s):
#(config)topology
#(config topology)redirector-ips
#(config topology redirector-ips) <add | clear-all | remove | view>

where

add: Add the IP address of a device redirecting to the CacheFlow
clear-all: Remove all IP addresses of devices redirecting to the CacheFlow
remove: Remove the IP address of a device redirecting to the CacheFlow
view: View configured redirector IP addresses
 
Redirector devices can use different kinds of health checks: ICMP PING, L4, or L7 (HTTP GET or HEAD). Best practice with L4/7 switches is to use HTTP GET/HEAD requests. Configuring the redirector IP(s) on the CacheFlow ensures that such health requests are responded to even when the CacheFlow is invoking capacity control. When no L4/7 switch is in use, PING may be the only health check format available to a PBR router. The CacheFlow will normally always respond to any PING, but when under extreme overload, this may cause a PBR router to falsely conclude that the CacheFlow is still capable of accepting additional traffic. With redirector IP(s) configured, the CacheFlow has the option of not responding to PINGs from the redirector, in order to signal an extreme overload


Example, if the health check from the LB has a source IP of 192.168.1.5 (you can configure more than 1 IP address if the HC comes from more than 1 IP):

CF5000#(config)topology
CF5000#(config topology)redirector-ips
CF5000#(config topology redirector-ips)add 192.168.1.5
  ok
CF5000#(config topology redirector-ips)view
Redirector IP addresses:
 192.168.1.5