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Device Manager Guide, Cisco ACE 4700 Series Application Control Engine Appliance
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Chapter 7 Configuring Stickiness
Stickiness Overview
Figure 7-2 Buddy Sticky Groups: Asymmetric Association
The ACE is configured to send client traffic with Layer 3 matches to server farm foobar, which contains
the nested server farms foo and bar. The ACE load balances the client traffic to one of the nested server
farms based on Layer 7 class map matches. By defining buddy sticky groups, the ACE is also able to
stick non-matching client traffic to the same real server.
In this example, the client sends traffic with Layer 3 matches that the ACE directs and sticks (using ip
sticky) to server farm foobar. The ACE uses a Layer 7 class map to check for HTTP URL and if present,
sends the traffic to server farm foo and sticks the client traffic to that server using sticky that is based on
the source IP address. Using a buddy stick group, the ACE uses the sticky entry to send any other traffic
type from the client to the same real server. For example, if the ACE sticks the client HTTP traffic to
server farm foo:real server lnx1 based on a Layer 7 class map match, the buddy stick group allows the
ACE to send non-HTTP traffic from the client to the same real server.
Many-to-One Association Example
In a many-to-one buddy sticky group association, you create a buddy sticky group that sticks a group of
real servers to a specific real server, which is useful when clients are load balanced to a first-tier server
farm containing many real servers and are then directed to a second tier server farm that contains fewer
real servers. In this type of application, you create buddy sticky groups that stick each first-tier real
server group to a specific second-tier real server.
In the network example shown in Figure 7-3, the ACE is configured with the following server farms,
their associated real servers, and assigned real server buddy groups:
1nx1
192.168.1.11
Internet
Client
Multilayer
Switch
Feature Card
ACE
VLAN 20
VLAN 40
172.16.1.1
192.168.1.1
Int: 172.16.1.5
VIP 172.16.1.100
Server Farm
foo
(alpha)
1nx2
192.168.1.12
Server Farm
bar
(alpha)
Server Farm
foobar
(alpha)
red
blue
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