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New Member

CSM, GSLB config for the Active/standby Datacenter

hi,

I need a sample config for GSLB for the A/S datacenter design. GSLB is configured on CSM.

Another question is, should i place CSM on core 6500 switch or on the Datacenter 6500 switch for GSLB operation?

Thanx

11 REPLIES
New Member

Re: CSM, GSLB config for the Active/standby Datacenter

any link on GSLB sample config with diagram will also be helpful.

New Member

Re: CSM, GSLB config for the Active/standby Datacenter

Here's how we do ours using GSLB:

serverfarm SF_DOMAIN dns-vip

real 1.2.3.4

weight 5

no inservice

real 5.6.7.8

weight 5

inservice

!

map MAP_DOMAIN dns

match protocol dns domain http://www.domain.com

!

policy POL_DOMAIN dns

dns map MAP_DOMAIN

serverfarm primary SF_DOMAIN ttl 10 responses 1

!

vserver VSRV_DOMAIN dns

dns-policy POL_DOMAIN

inservice

!

New Member

Re: CSM, GSLB config for the Active/standby Datacenter

hi,

thanx for the reply.

I configured GSLB for testing purpose with

a DNS server in the server farm.

when i check from outside by nslookup, DNS replies with its own IP not the IP address of the server im requesting for.

Any idea what entries should be configured on the DNS server, and how to map multiple IPs to single name on DNS.

Also on the client which IP must be configured as primary DNS, CSM IP???

New Member

Re: CSM, GSLB config for the Active/standby Datacenter

Perhaps if you could paste the relevant sections of your config? There should be a map, policy, dns-vip vserver, and a serverfarm.

The configuration that I posted is the, slightly modified, working production code on our CSMs.

New Member

Re: CSM, GSLB config for the Active/standby Datacenter

Here is attachement which possibly gives u an idean about my issue along with GSLB configuration i used for testing purpose.

Please correct if im wrong in design approach as well as correct if something is missing or wrong with GSLB.

the situation is typical and i must get it working soon.

thanx

New Member

Re: CSM, GSLB config for the Active/standby Datacenter

any one out there to help. thanx

Cisco Employee

Re: CSM, GSLB config for the Active/standby Datacenter

we can't read your doc file.

A sample config was given to you already.

Configure the dns-vip serverfarm with the dns-ip you want the CSM to return in case of a dns-query.

With GSLB, you do not need a DNS-server.

If you have dns servers and you want the CSM to loadbalance dns request, then you SHOULD NOT use GSLB.

Simply configure the CSM for dns/udp loadbalancing.

Please clarify what you want to do exactly.

Gilles.

New Member

Re: CSM, GSLB config for the Active/standby Datacenter

hi Gilles,

sorry about the previous attachment.

Im attaching PPT attachment with my basic rquirement. please ask for any further info you need. I thought GSLB would be the solution but have no idea about how exactly GSLB works. GSLB DNS server farm I have added in the diagram assuming that GSLB needs DNS server, it can be removed.

Please refer to attachment.

Info on what is required.

User connects to terminal server farm on DC1 to access active server.

When users cannot reach active server (either because of failure of terminal servers on DC1 or Active server) then users must be automatically redirected to terminal servers on DC2 through which they can access the standby server.

Standby server monitors the active server and if user is not reachable to active server (either because of failure of terminal servers on DC1 or Active server) it assumes the responsibility of active server and becomes active.

Issue:

But the issue is how does the network is going to redirect users traffic to the new active server which is on another datacenter

Note:

Users access to Active/standby servers in only through their respective terminals server farm

Cisco Employee

Re: CSM, GSLB config for the Active/standby Datacenter

thanks for the diagram and the explanation of the issue.

Let me first say the recommended solution is to use a Global Site Selector (GSS) http://www.cisco.com/en/US/products/hw/contnetw/ps4162/index.html.

This is some kind of smart dns device.

It can monitor a destination to see if it is alive before responding to the dns request.

If you can't use a GSS, the GSLB option of the CSM might help.

In this case the CSM itself becomes the dns server. You still need a DNS server to handle most of the dns function. The csm would just handle parts of your domain ie: the primary dns server takes care of .mydomain.com and it lets the CSM handle the part related to www.mydomain.com.

So, keep in mind that the CSM will provide the dns response.

When you configure the dns-vip serverfarm, you have to configure a real ip that represents the answer that will be given by the CSM.

You can use a primary serverfarm and a secondary [in case the first one is down].

This is explain at

http://www.cisco.com/en/US/products/hw/switches/ps708/module_installation_and_configuration_guides_chapter09186a0080212af5.html#wp1037979

See the example that was given to you and read the document from the link above and then give it a try.

If you have further questions after that, feel free to come back on this forum.

Gilles.

New Member

Re: CSM, GSLB config for the Active/standby Datacenter

plz let me know wether my understanding towards the solution is correct.

Reffering to the diagram in the above attachment.

1. DNS server in the campus core handle most of the DNS function, And it is congfured as a forwarder to one the CSM IP address( server/client vlan)

2. DNS servers farm is NOT required behind CSM for GSLB operations.

3. Both DC1 & DC2 has CSM. but i need to set up GSLB in only say DC1. ( or on both??)

4. In dns-vip i have to configure IP 192.168.2.200 and 192.168.4.200 i.e of active and standby servers

5. CMS will probe 192.168.2.200 & 192.168.4.200 for a DNS request from client and respond with only one IP adress, which is of active server.

correct me on the above points whereever im wrong.

Thanx

Cisco Employee

Re: CSM, GSLB config for the Active/standby Datacenter

1 & 2 are correct.

3. you should probably configure GSLB on both CSM and have your primary dns server have 2 forwarder.

4. You need to create 2 serverfarm. One will be the primary used all the time except if it goes down in which case the secondary kicks in.

5. You have to configure the probes. The CSM will keep monitoring the status of the probe so it is ready to answer the dns request when it comes. It will respond with 1 ip address.

Gilles.

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