CSM Backup serverfarm prob.

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May 22nd, 2008
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I have two 6509 and two CSM module.

serverbank-I is conected with the 6509-1 and second serverbank-II is connected to 6509-2, and 6509-1 and 6509-2 are connected to each other via CWDM link,

I can access all the real servers from both switches,

My problem is,

If i configured serverfarm-I with Backup srverfarm-II on both the csm module it will work ?

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ebreniz Wed, 05/28/2008 - 12:40
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The CSS only allow 1 backup server. When a client is connected to a server, it stays connected to that server even if a new server goes up. Only new connections from the client would be sent to a different server.

We are building a transparent caching scenario with CSM running 4.2(3) on a cat6509 with sup2msfc2pfc2 running 12.2.(18)SXD7. The CEs are 7325A and are running ACNS 5.2.7b7.To test the backup server farm feature we configured a server farm called CE-FARM:


server farm CE-FARM

no nat server

no nat client

predictor hash url

failaction reassign

real 192.168.6.1

inservice

probe ICMP-PROBE


Cat6509#show mod csm 8 serverfarms name ce-farm detail

CE-FARM, type = SLB, predictor = URL Hash

nat = None

virtuals inservice = 2, reals = 1, bind id = 0, fail action = reassign

inband health config:

retcode map =

Probes:

ICMP-PROBE, type = icmp

Real servers:

192.168.6.1, weight = 8, OPERATIONAL, conns = 17

Total connections = 17


This server farm (CE-FARM) is our main server farm.

The backup server farm is called dummy and for testing the backup feature its configuration is:


serverfarm DUMMY

no nat server

no nat client

predictor hash url

failaction reassign

real 192.168.6.5

no inservice

real 192.168.6.6

no inservice

real 192.168.6.4

no inservice

real 192.168.6.3

no inservice

real 192.168.6.2

no inservice

probe ICMP-PROBE

!

Cat6509#show mod csm 8 serverfarms name dummy detail

DUMMY, type = SLB, predictor = URL Hash

nat = None

virtuals inservice = 1, reals = 5, bind id = 0, fail action = reassign

inband health config:

retcode map =

Probes:

ICMP-PROBE, type = icmp

Real servers:

192.168.6.5, weight = 8, OUTOFSERVICE, conns = 0

192.168.6.6, weight = 8, OUTOFSERVICE, conns = 0

192.168.6.4, weight = 8, OUTOFSERVICE, conns = 0

192.168.6.3, weight = 8, OUTOFSERVICE, conns = 0

192.168.6.2, weight = 8, OUTOFSERVICE, conns = 0

Total connections = 0


Then we associated these two server farms in a vserver called DUMMY for which server farm CE-FARM is the "main" server farm and server farm DUMMY is the backup.


The vserver DUMMY is associated with the overall configuration of the scenario but for now I ask you to consider its existence only for propose of testing the backup server farm feature.


vserver DUMMY configuration is:

vserver DUMMY

virtual 192.168.9.250 any

advertise active

persistent rebalance

slb-policy DUMMY

inservice


where slb-policy DUMMY has the following configuration:


policy DUMMY

serverfarm CE-FARM backup DUMMY threshold inservice 4 outservice 3


From the above configuration we were expecting the following:


-server farm dummy would be used in case less then 3 reals were available on the server farm CE-FARM.


-server farm CE-FARM would be RE-used in case at least 4 real were available.


Cat6509#show mod csm 8 vservers name dummy detail

DUMMY, type = SLB, state = OPERATIONAL, v_index = 12

virtual = 192.168.9.250/32:0 bidir, any, service = NONE, advertise = TRUE

idle = 3600, replicate csrp = none, vlan = ALL, pending = 30, layer 7

max parse len = 2000, persist rebalance = TRUE

ssl sticky offset = 0, length = 32

conns = 0, total conns = 0

Policy Tot matches Client pkts Server pkts

---------------------------------------------

DUMMY 0 0 0

(default) 0 0 0

Cat6509#show mod csm 8 policy name DUMMY

policy: DUMMY

type: SLB

serverfarm: CE-FARM

backup serverfarm: DUMMY (no sticky)


With this scenario we were expecting that with all reals in server farm DUMMY out of service and only one real inservice in server farm CE-FARM the vserver DUMMY would be out of service.


This configuration is strange ... in fact we are testing a way of influencing the MSFC routing table (please notice advertise active command on vserver DUMMY config) when a certain number of CEs is out of service.




Syed Iftekhar Ahmed Thu, 05/29/2008 - 12:00
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Yes. It will.

Make sure that the client/server vlans exist on both chasis and are trunked between two chassis.


Syed

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