Problem with ACE Module MAX-LOAD

Alvaro Perez Unzueta · ‎02-17-2010

Hello Everybody,

I have a problem, i've configured an ACE Module, but sometimes the state of real server is flapping betwen OPERATIONAL and

MAX-LOAD, I've seen that load value when this hapend this (MAX-LOAD) take the load value 16000 in the real server was2, but when the state is OPERATIONAL the load value of the real server is 480. anybody know how to correct this situation?

Thank You

The output i show.

ACE-MOD6/integracion1# sh serverfarm servers_unique
serverfarm     : servers_unique, type: HOST
total rservers : 3
---------------------------------
                                                ----------connections-----------
       real                  weight state        current    total      failures
   ---+---------------------+------+------------+----------+----------+---------
   rserver: was1
       10.24.18.10:0         8      OPERATIONAL 10         1110975    0
   rserver: was2
       10.24.18.11:0         8      MAX-LOAD     1          843815     3
   rserver: was3
       10.24.18.12:0         8      OUTOFSERVICE 0          177        0

ACE-MOD6/integracion1# sh serverfarm servers_unique detail
serverfarm     : servers_unique, type: HOST
total rservers : 3
active rservers: 1
description    : -
state          : ACTIVE
predictor      : LEASTLOADED
   weight            : -
   autoadjust        : MAXLOAD
failaction     : -
back-inservice    : 0
partial-threshold : 0
num times failover       : 249
num times back inservice : 252
total conn-dropcount : 0
---------------------------------
                                                ----------connections-----------
       real                  weight state        current    total      failures
   ---+---------------------+------+------------+----------+----------+---------
   rserver: was1
       10.24.18.10:0         8      OPERATIONAL 10         1110979    0
         max-conns            : 4000000   , out-of-rotation count : 0
         min-conns            : 4000000
         conn-rate-limit      : -         , out-of-rotation count : -
         bandwidth-rate-limit : -         , out-of-rotation count : -
         retcode out-of-rotation count : -
         load value           : 480

   rserver: was2
       10.24.18.11:0         8      MAX-LOAD     1          843815     3
         max-conns            : 4000000   , out-of-rotation count : 0
         min-conns            : 4000000
         conn-rate-limit      : -         , out-of-rotation count : -
         bandwidth-rate-limit : -         , out-of-rotation count : -
         retcode out-of-rotation count : -
         load value           : 16000

   rserver: was3
       10.24.18.12:0         8      OUTOFSERVICE 0          177        0
         max-conns            : 4000000   , out-of-rotation count : 0
         min-conns            : 4000000
         conn-rate-limit      : -         , out-of-rotation count : -
         bandwidth-rate-limit : -         , out-of-rotation count : -
         retcode out-of-rotation count : -
         load value           : 80

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

ACE-MOD6/integracion1# sh serverfarm servers_unique
serverfarm     : servers_unique, type: HOST
total rservers : 3
---------------------------------
                                                ----------connections-----------
       real                  weight state        current    total      failures
   ---+---------------------+------+------------+----------+----------+---------
   rserver: was1
       10.24.18.10:0         8      OPERATIONAL 8          1110985    0
   rserver: was2
       10.24.18.11:0         8      OPERATIONAL 3          843819     3
   rserver: was3
       10.24.18.12:0         8      OUTOFSERVICE 0          177        0

ACE-MOD6/integracion1# sh serverfarm servers_unique detail
serverfarm     : servers_unique, type: HOST
total rservers : 3
active rservers: 2
description    : -
state          : ACTIVE
predictor      : LEASTLOADED
   weight            : -
   autoadjust        : MAXLOAD
failaction     : -
back-inservice    : 0
partial-threshold : 0
num times failover       : 249
num times back inservice : 252
total conn-dropcount : 0
---------------------------------
                                                ----------connections-----------
       real                  weight state        current    total      failures
   ---+---------------------+------+------------+----------+----------+---------
   rserver: was1
       10.24.18.10:0         8      OPERATIONAL 6          1110995    0
         max-conns            : 4000000   , out-of-rotation count : 0
         min-conns            : 4000000
         conn-rate-limit      : -         , out-of-rotation count : -
         bandwidth-rate-limit : -         , out-of-rotation count : -
         retcode out-of-rotation count : -
         load value           : 480

   rserver: was2
       10.24.18.11:0         8      OPERATIONAL 2          843821     3
         max-conns            : 4000000   , out-of-rotation count : 0
         min-conns            : 4000000
         conn-rate-limit      : -         , out-of-rotation count : -
         bandwidth-rate-limit : -         , out-of-rotation count : -
         retcode out-of-rotation count : -
         load value           : 480

   rserver: was3
       10.24.18.12:0         8      OUTOFSERVICE 0          177        0
         max-conns            : 4000000   , out-of-rotation count : 0
         min-conns            : 4000000
         conn-rate-limit      : -         , out-of-rotation count : -
         bandwidth-rate-limit : -         , out-of-rotation count : -
         retcode out-of-rotation count : -
         load value           : 80

ACE-MOD6/integracion1# sh run
Generating configuration....

access-list anyone line 8 extended permit ip any any

probe http HTTP-get-index
interval 4
faildetect 2
passdetect interval 10
receive 2
expect status 200 200
open 2
probe https HTTPS-get-index
interval 4
faildetect 2
passdetect interval 10
receive 2
ssl cipher RSA_WITH_RC4_128_MD5
expect status 200 200
open 2
probe snmp test-server
interval 4
faildetect 2
passdetect interval 10
receive 2
community public
oid .1.3.6.1.2.1.25.3.3.1.2.1
    threshold 60
    weight 8000
oid .1.3.6.1.2.1.25.3.3.1.2.2
    threshold 60
    weight 8000

rserver host des1
ip address 10.24.18.34
inservice
rserver host des2
ip address 10.24.18.35
inservice
rserver host was1
ip address 10.24.18.10
inservice
rserver host was2
ip address 10.24.18.11
inservice
rserver host was3
ip address 10.24.18.12

serverfarm host servers_unique
predictor least-loaded probe test-server
rserver was1
    probe HTTP-get-index
    probe HTTPS-get-index
    inservice
rserver was2
    probe HTTPS-get-index
    probe HTTP-get-index
    inservice
rserver was3
    probe HTTP-get-index
serverfarm host servers_unique_granja
rserver des1
    inservice
rserver des2
    inservice

class-map type management match-any ADM-CONTEX-SERV1
2 match protocol telnet any
3 match protocol ssh any
4 match protocol icmp any
5 match protocol snmp any
class-map type http loadbalance match-all Check-Headers
2 match http url .*
3 match http header Host header-value "10.24.16.*"
4 match http header User-Agent header-value ".*MSIE.*"
class-map type http loadbalance match-all Check-Headers-12
2 match http url .*
3 match http header Host header-value "10.24.16.*"
4 match http header User-Agent header-value ".*MSIE.*"
class-map match-all VIP-10-HTTP
2 match virtual-address 10.24.16.10 tcp eq www
class-map match-all VIP-10-HTTPS
2 match virtual-address 10.24.16.10 tcp eq https
class-map type http loadbalance match-all other-HTTP
2 match http url .*
class-map type http loadbalance match-all other-http-12
2 match http url .*
class-map match-all server-vlan-vip-12-http
2 match virtual-address 10.24.16.12 tcp eq www
class-map match-all server-vlan-vip-12-https
2 match virtual-address 10.24.16.12 tcp eq https

policy-map type management first-match ADM-CTX-SERV1
class ADM-CONTEX-SERV1
permit

policy-map type loadbalance first-match L7-logic
class Check-Headers
    serverfarm servers_unique
class other-HTTP
    serverfarm servers_unique
policy-map type loadbalance first-match http-12-lb
class Check-Headers-12
    serverfarm servers_unique_granja
class other-http-12
    serverfarm servers_unique_granja
policy-map type loadbalance first-match lb-logic
class class-default
    serverfarm servers_unique
policy-map type loadbalance first-match lb-logic-12
class class-default
    serverfarm servers_unique_granja

policy-map multi-match client-vips
class VIP-10-HTTP
    loadbalance vip inservice
    loadbalance policy L7-logic
    loadbalance vip icmp-reply active
class VIP-10-HTTPS
    loadbalance vip inservice
    loadbalance policy lb-logic
    loadbalance vip icmp-reply active
policy-map multi-match server-vip-service-policy-12
class server-vlan-vip-12-http
    loadbalance vip inservice
    loadbalance policy http-12-lb
    loadbalance vip icmp-reply
class server-vlan-vip-12-https
    loadbalance vip inservice
    loadbalance policy lb-logic-12
    loadbalance vip icmp-reply

interface vlan 233
description Servidores_Balanceados_outside
ip address 10.24.16.5 255.255.255.0
access-group input anyone
access-group output anyone
service-policy input ADM-CTX-SERV1
service-policy input client-vips
no shutdown
interface vlan 240
description Balanceados_Was
ip address 10.24.18.2 255.255.255.240
peer ip address 10.24.18.3 255.255.255.240
access-group input anyone
access-group output anyone
service-policy input ADM-CTX-SERV1
service-policy input server-vip-service-policy-12
no shutdown

ip route 0.0.0.0 0.0.0.0 10.24.16.2

Sean Merrow · ‎02-17-2010

Hello,

What you are seeing is likely due to the following default behavior of the ACE:

"Whenever a server's load reaches zero, by default, the ACE uses the autoadjust feature to assign a maximum load value of 16000 to that server to prevent it from being flooded with new incoming connections. The ACE periodically adjusts this load value based on feedback from the server's SNMP probe and other configured options."

See more details at the following link. You might want to set the autoadjust to average or just turn it off.

Using Autoadjust

http://www.cisco.com/en/US/docs/interfaces_modules/services_modules/ace/vA2_3_0/configuration/slb/guide/rsfarms.html#wp1070144

Hope this helps,

Sean