8-34

User

Guide

for

the

Cisco

Application

Networking

Manager

5.2

OL-26572-01

Chapter

8

Configuring

Real

Servers

and

Server

Farms

Configuring

Server

Farms

Inband-Health

Check

Option

that

is

available

only

for

the

ACE

module

A4(1.0),

ACE

appliance

A4(1.0),

and

later

releases

of

either

device

type.

Field

that

appears

only

for

host

server

farms.

By

default,

the

ACE

monitors

the

health

of

all

real

servers

in

a

configuration

through

t

he

use

of

ARPs

and

health

probes.

However,

there

is

latency

period

between

when

the

real

server

goes

down

and

when

the

ACE

becomes

aware

of

the

state.

The

inband

health

monitoring

feature

allows

the

ACE

to

monitor

the

health

of

the

real

servers

in

the

server

farm

through

the

following

connection

failures:

•

For

TCP,

resets

(RSTs)

from

the

server

or

SYN

timeouts.

•

For

UDP,

ICMP

Host,

Network,

Port,

Protocol,

and

Source

Route

unreachable

messages.

When

you

configure

the

failure-count

threshold

and

the

number

of

these

failures

exceeds

the

threshold

within

the

reset-time

interval,

the

ACE

immediately

marks

the

server

as

failed,

takes

it

out

of

service,

and

removes

it

from

load

balancing.

The

server

is

not

considered

for

load

balancing

until

the

optional

resume-service

interval

expires.

The

Inband-Health

Check

attributes

are

as

follows:

•

Count—Tracks

the

t

otal

number

of

TC

P

or

UDP

failures,

and

increments

the

counters.

•

Log—Logs

a

syslog

error

message

when

the

number

of

events

reaches

the

threshold

value

that

you

set

for

the

Connection

Failure

Threshold

Count

attribute.

•

Remove—Logs

a

syslog

er

ror

message

when

the

number

of

events

reaches

the

configured

threshold

and

removes

the

real

server

from

ser

vice.

Connection

Failure

Threshold

Count

This

field

appears

only

when

the

Inband-Health

Check

is

set

to

Log

or

Remove.

Enter

the

maximum

number

of

connection

failures

that

a

real

server

can

exhibit

in

the

reset-time

interval

before

ACE

marks

the

real

server

as

failed.

Valid

entries

are

as

follows:

•

ACE

appliance—1

to

4294967295

•

ACE

module—4

to

4294967295

Reset

Timeout

(Milliseconds)

This

field

appears

only

when

the

Inband-Health

Check

is

set

to

Log

or

Remove.

Enter

the

number

of

milliseconds

for

the

reset-time

interval.

Valid

entries

are

integers

from

100

to

300000.

The

default

interval

is

100.

This

interval

starts

when

the

ACE

detects

a

connection

failure.

If

the

connection

failure

threshold

is

reached

during

this

interval,

the

ACE

generates

a

syslog

message.

If

you

configure

the

remove

keyword,

the

ACE

al

so

removes

t

he

real

server

fr

om

service.

Changing

the

setting

of

this

option

affects

the

behavior

of

the

real

server,

as

follows:

•

When

the

real

server

is

in

the

OPERATIONAL

state,

even

if

several

connection

failures

have

occurred,

the

new

reset-time

interval

takes

effect

the

next

time

that

a

connection

error

occurs.

•

When

the

real

server

in

the

INBAND-HM-FAILED

state,

the

new

reset-time

interval

takes

effect

the

next

time

that

a

connection

error

occurs

after

the

server

transitions

to

the

OPERATIONAL

state.

Table

8-7

Server

Farm

Attributes

(continued)

Field

Description