Getting Started Guide, Cisco ACE Application Control Engine Module
Configuring Health Monitoring Using Health Probes
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Table Of Contents

Configuring Health Monitoring Using Health Probes

Information About Configuring Health Monitoring

Prerequisites for Configuring Health Monitoring

Configuring an HTTP Health Probe

Configuration Example for an HTTP Health Probe

Where to Go Next


Configuring Health Monitoring Using Health Probes

This chapter describes how to configure a health probe on the Cisco Application Control Engine (ACE) module.

This chapter contains the following sections:

•Information About Configuring Health Monitoring

•Prerequisites for Configuring Health Monitoring

•Configuring an HTTP Health Probe

•Configuration Example for an HTTP Health Probe

•Where to Go Next

Information About Configuring Health Monitoring

After reading this chapter, you should have a basic understanding of how the ACE supports server health monitoring using health probes (sometimes referred to as "keepalives"), and how to configure an HTTP health probe.

To detect failures and make reliable load-balancing decisions, you can configure the ACE to track the health of servers and server farms by periodically sending out health probes. By default, the ACE implicitly checks for server failures.

You can configure probes on the ACE to make active connections and explicitly send traffic to servers. The ACE evaluates the server's response to determine the health of that server.

When the ACE determines the health of a server, the result is one of the following:

•Passed—The server returned a valid response.

•Failed—The server failed to provide a valid response to the ACE within a specified number of retries.

When a server fails in response to the probe, the ACE can check for network problems that prevent a client from accessing that server. The ACE can place the server out of service.

A probe can be any of several types, including HTTP, HTTPS, ICMP, TCP, Telnet, and UDP. You can also configure scripted probes using the TCL scripting language.

This chapter describes how to configure an HTTP probe. For information on how to configure other types of probes, see the Server Load-Balancing Guide, Cisco ACE Application Control Engine.

Prerequisites for Configuring Health Monitoring

Before you can configure health monitoring, you must configure one or more servers or a server farm. For details, see Chapter 6, Configuring Server Load Balancing.

Configuring an HTTP Health Probe

Procedure

 
Command
Purpose

Step 1  

changeto context

Example: 

host1/Admin# changeto VC_WEB

host1/VC_WEB#

Changes to the correct context if necessary. Check the CLI prompt to verify that you are operating in the desired context.

Step 2  

config

Example: 

host1/VC_WEB# config

host1/VC_WEB(config)#

Enters configuration mode.

Step 3 

probe http name

Example: 

host1/VC_WEB(config)# probe http 
HTTP_PROBE1

host1/VC_WEB(config-probe-http)#

Define an HTTP probe named HTPP_probe1 to access its configuration mode.

Step 4  

expect status min_number max_number

Example: 

host1/VC_WEB(config-probe-http)# expect 
status 200 200

Configures a single status code or a range of status code responses that the ACE expects from the probe destination. This parameter is required. Without it, all HTTP or HTTPS probes will fail.

Step 5 

exit

Example: 

host1/VC_WEB(config-probe-http)# exit

host1/VC_WEB(config)#

Exits probe configuration mode.

Step 6  

serverfarm name

Example: 

host1/VC_WEB(config)# serverfarm SF_WEB

host1/VC_WEB(config-sfarm-host)#

Enter server farm host configuration mode for the SF_WEB server farm.

Step 7  

probe name

Example: 

host1/VC_WEB(config-sfarm-host)# probe 
HTTP_PROBE1

Associate the probe HTTP_PROBE1 with the server farm SF_WEB.

Step 8 

exit

Example: 

host1/VC_WEB(config-sfarm-host)# exit

host1/VC_WEB(config)# exit

host1/VC_WEB#

Exits server farm host configuration mode. Exits configuration mode.

Step 9 

show running-config probe

Example: 

host1/VC_WEB# show running-config probe

Displays the running configuration to verify that the information that you just added is configured properly.

Step 10 

copy running-config startup-config

Example:

host1/VC_WEB# copy running-config startup-config

(Optional) Copies the running configuration to the startup configuration.

Configuration Example for an HTTP Health Probe

The following example shows how to configure an HTTP health probe. The commands that you have configured in this chapter appear in bold text. 

switch/VC_WEB(config)# do show running config

Generating configuration....

access-list INBOUND line 8 extended permit ip any any

probe http HTTP_PROBE1

  expect status 200 200

rserver host RS_WEB1

  description content server web-one

  ip address 10.10.50.10

  inservice

rserver host RS_WEB2

  description content server web-two

  ip address 10.10.50.11

  inservice

rserver host RS_WEB3

  description content server web-three

  ip address 10.10.50.12

  inservice

rserver host RS_WEB4

  description content server web-four

  ip address 10.10.50.13

  inservice

serverfarm host SF_WEB

  predictor hash header Accept

  probe HTTP_PROBE1

  rserver RS_WEB1 80

    inservice

  rserver RS_WEB2 80

    inservice

  rserver RS_WEB3 80

    inservice

  rserver RS_WEB4 80

    inservice

sticky http-cookie Cookie1 StickyGroup1

  timeout 3600

  serverfarm SF_WEB

ssl-proxy service SSL_PSERVICE_SERVER

  key cisco-sample-key

  cert cisco-sample-cert

class-map match-all CM_SSL

  2 match virtual-address 10.10.40.11 tcp eq https

class-map type management match-any REMOTE_ACCESS

  description Remote access traffic match

  2 match protocol ssh any

  3 match protocol telnet any

  4 match protocol icmp any

class-map match-all VS_WEB

  2 match virtual-address 10.10.40.10 tcp eq www

policy-map type management first-match REMOTE_MGMT_ALLOW_POLICY

  class REMOTE_ACCESS

    permit

policy-map type loadbalance first-match PM_LB

  class class-default

    serverfarm SF_WEB

policy-map multi-match PM_MULTI_MATCH

  class VS_WEB

    loadbalance vip inservice

    loadbalance policy PM_LB

policy-map multi-match PM_SSL

  class CM_SSL

    ssl-proxy server SSL_PSERVICE_SERVER

service-policy input REMOTE_MGMT_ALLOW_POLICY

interface vlan 400

  description Client connectivity on VLAN 400

  ip address 10.10.40.1 255.255.255.0

  access-group input INBOUND

  service-policy input PM_MULTI_MATCH

  service-policy input PM_SSL

  no shutdown

interface vlan 500

  description Server connectivity on VLAN 500

  ip address 10.10.50.1 255.255.255.0

  no shutdown

domain DOMAIN1

add-object all

ip route 0.0.0.0 0.0.0.0 172.25.91.1

username USER1 password 5 $1$vAN9gQDI$MmbmjQgJPj45lxbtzXPpB1  role SLB-Admin domain 
DOMAIN1

Where to Go Next

In this chapter, you have configured an HTTP health probe. In the next chapter, you will configure route health injection (RHI).