07-26-2010 07:26 PM
Hi,
I would like to ask regarding the configuration for the backup rserver with sticky configured.
This is not documented in the Cisco guides.
Suppose the real server1 fails and connections are diverted to server2. Then server1 resumes service. What happens to existing connections on server2 and the new connections?
serverfarm SFARM1
rserver SERVER1
backup-rserver SERVER2
inservice
rserver SERVER2
inservice standby
08-02-2010 01:34 AM
- Existing connections keep accessing server2.
- If a new client request (connection) matches a sticky entry for server2, ACE forwards this request to server2.
- If a new client request (connection) doesn't match any sticky entry for server2, ACE forwards this request to server1.
serverfarm SFARM1
rserver SERVER1
inservice
serverfarm SFARM2
rserver SERVER2
inservice
sticky ip-netmask 255.255.255.255 address both sticky_ip
serverfarm SFARM1 backup SFARM2
The following is a test result of standby rserver and sticky ip.
ACE20a/Admin# sh rserver
rserver : sv1, type: HOST
state : OPERATIONAL (verified by arp response)
---------------------------------
----------connections-----------
real weight state current total
---+---------------------+------+------------+----------+--------------------
serverfarm: sf
192.168.72.11:0 8 PROBE-FAILED 0 2
rserver : sv2, type: HOST
state : OPERATIONAL (verified by arp response)
---------------------------------
----------connections-----------
real weight state current total
---+---------------------+------+------------+----------+--------------------
serverfarm: sf
192.168.72.12:0 8 OPERATIONAL 0 8
ACE20a/Admin#
!___ access from client to ACE vip
ACE20a/Admin# sh sticky database
sticky group : sticky_ip
type : IP
timeout : 1440 timeout-activeconns : FALSE
sticky-entry rserver-instance time-to-expire flags
---------------------+--------------------------------+--------------+-------+
13882423967172020068 sv2:0 86384 -
!___ ACE learns client address and registers the entry
ACE20a/Admin#
ACE20a/Admin# sh rserver
rserver : sv1, type: HOST
state : OPERATIONAL (verified by arp response)
---------------------------------
----------connections-----------
real weight state current total
---+---------------------+------+------------+----------+--------------------
serverfarm: sf
192.168.72.11:0 8 OPERATIONAL 0 2
!___ return OPERATIONAL
rserver : sv2, type: HOST
state : OPERATIONAL (verified by arp response)
---------------------------------
----------connections-----------
real weight state current total
---+---------------------+------+------------+----------+--------------------
serverfarm: sf
192.168.72.12:0 8 STANDBY 0 9
!___ return STANDBY
ACE20a/Admin# sh sticky database
sticky group : sticky_ip
type : IP
timeout : 1440 timeout-activeconns : FALSE
sticky-entry rserver-instance time-to-expire flags
---------------------+--------------------------------+--------------+-------+
13882423967172020068 sv2:0 86356 -
!___ ACE keeps sticky entry to server2.
ACE20a/Admin#
!___ access from client with new syn packet
ACE20a/Admin# sh sticky database
sticky group : sticky_ip
type : IP
timeout : 1440 timeout-activeconns : FALSE
sticky-entry rserver-instance time-to-expire flags
---------------------+--------------------------------+--------------+-------+
13882423967172020068 sv2:0 86389 -
!___ use this sticky entry (time-to-expire flag is reset) and send packets to server2
ACE20a/Admin#
ACE20a/Admin# sh ver | i image
system image file: [LCP] disk0:c6ace-t1k9-mz.A2_3_1.bin
08-02-2010 02:02 AM
Hi Yushimaz,
Thanks for your insightful and very helpful reply.
However I would like to confirm with you on something:
So when server1 goes to operational, server2 will still take in connections as long as it have an entry in its sticky table database. Will the server2 stops taking connections once all of its sticky database is cleared?
Thanks!
08-02-2010 07:13 PM
Hi jsarausos
When sticky database is cleared by clear sticky database command or timed out,
new connection will forward to server1 but existing connection will keep the connection
to server2 since ACE looks up connection table.
If you use sticky cookie insert feature, you may have to remove cookie by hand or
use browser-expire option since sticky database has never expired.
The following is the behavior after sticky database on ACE is cleared.
ACE20a/Admin# sh sticky database
sticky group : sticky_ip
type : IP
timeout : 1440 timeout-activeconns : FALSE
sticky-entry rserver-instance time-to-expire flags
---------------------+--------------------------------+--------------+-------+
13882423967172020068 sv2:0 86373 -
!___ primary rserver went down and then ACE learned a sticky entry for sv2.
ACE20a/Admin#
ACE20a/Admin# clear sticky database all
!___ issued clear command to remove all sticky entries
ACE20a/Admin# sh sticky database
ACE20a/Admin#
!___ all entries were cleared and then client sent a new request.
ACE20a/Admin# sh sticky database
sticky group : sticky_ip
type : IP
timeout : 1440 timeout-activeconns : FALSE
sticky-entry rserver-instance time-to-expire flags
---------------------+--------------------------------+--------------+-------+
13882423967172020068 sv1:0 86395 -
!___ ACE sent this request to server1 and created the entry.
ACE20a/Admin#
Regards,
Yuji
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