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Problem(Abstract) |
The mac forwarding method requires aliasing the loopback
device on server machines that are being load-balanced. AIX 5.x servers
require additional steps when configuring the loopback device. |
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Resolving the
problem |
When using the Dispatcher's mac forwarding method, the
follow these steps to set up AIX 5.x server machines for load balancing:
Step 1. Alias the loopback device. Type:
ifconfig lo0 alias cluster_address netmask netmask_value
For example: ifconfig lo0 alias 9.27.176.131 netmask 255.255.255.0
Step 2. Check for an extra route. Type:
netstat -nr
Sample output:
Routing tables:
Route Tree for Protocol Family 2 (Internet):
Destination
|
Gateway
|
Flags
|
Refs
|
Use
|
If
|
PMTU
|
Exp
|
Groups
|
default
|
9.27.176.1
|
UGc
|
0
|
0
|
en0
|
-
|
-
|
 |
9.27.23.42 |
9.27.176.1
|
UGHW
|
1
|
19
|
en0
|
-
|
-
|
 |
9.27.176/24 |
9.27.176.58
|
U
|
4
|
11726
|
en0
|
-
|
-
|
=>
|
9.27.176/24 |
9.27.176.131
|
U
|
0
|
8
|
lo0
|
-
|
-
|
 |
9.27.176.58 |
127.0.0.1
|
UGHS
|
23
|
157640
|
lo0
|
-
|
-
|
 |
9.44.5.140
|
9.27.176.1
|
UGHW
|
0
|
84919
|
en0
|
-
|
1
|
 |
10.0.7/24
|
10.0.7.4
|
U
|
0
|
3
|
en1
|
-
|
-
|
 |
10.0.7.4
|
127.0.0.1
|
UGHS
|
0
|
0
|
lo0
|
-
|
-
|
 |
10.5.32/24
|
10.5.32.4
|
U
|
0
|
2
|
tr0
|
-
|
-
|
 |
10.5.32.4
|
127.0.0.1
|
UGHS
|
0
|
1
|
lo0
|
-
|
-
|
 |
127/8
|
127.0.0.1
|
U
|
3
|
136835
|
lo0
|
-
|
-
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Route Tree for Protocol Family 24 (Internet v6):
Destination
|
Gateway
|
Flags
|
Refs
|
Use
|
If
|
PMTU
|
Exp
|
Groups
|
::1
|
::1
|
UH
|
0
|
0
|
lo0
|
16896
|
-
|
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If there is an extra route, you will see the network portion of the alias
you just added with the an interface of lo0. Delete this route to prevent
packets destined for the network from going through the loopback address.
Step 3. Delete any extra route
For example : route delete 9.27.176/24 9.27.176.131
Step 4. Verify server is properly configured.
1. Type: arp -d cluster (This removes the cluster address from the arp
cache.)
2. From another machine, type: ping cluster (There should be no response.
If there is a response, ensure that you did not ifconfig the cluster
address to the interface and that no machine has a published arp entry to
the cluster address.)
3. From another machine, ping the back-end server. Then, immediately
type:
arp -s MEDIA cluster server_mac_address
where MEDIA is either 802.3, 802.5, or FDDI depending on the media
type.
To unconfigure the loopback address, type:
ifconfig lo0 delete cluster_address netmask
netmask_value |
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Cross Reference information |
Segment |
Product |
Component |
Platform |
Version |
Edition |
Application Servers |
WebSphere Edge Server |
Load Balancer |
AIX |
Edge Server 2.0 GA, Edge Server 2.0 NLV, Edge Server 2.0 PTF1, Edge
Server 2.0 PTF2, Edge Server 2.0.x |
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Application Servers |
Runtimes for Java Technology |
Java SDK |
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