GSS and DistributedDirector appliance

Answered Question
Jul 28th, 2008

I could not understand the difference between the Cisco Global Site Selector and Cisco Distributed Director Appliance. Does Distributed Director is End of Sale?

The idea I gather from cisco.com is Distributed Director appliacne utilizes Cisco IOS software while GSS works with ACE to direct client to the closest server.

I have this problem too.
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Syed Iftekhar Ahmed Mon, 07/28/2008 - 00:59

GSS is primarily a functional replacement of DD. DD is an aged GSLB solution from cisco that became an IOS feature set after 12.2+ IOS images.

GSS is Cisco's current global server load balancing (GSLB) solution.It provide

1.Global Server Load Balancing for geographically dispersed Server Load Balancers and Caches

2.DNS selection of Disaster Recovery sites

3.Connect clients to the best server based on:

Network topology

Server load

Availability of content and devices

4.Responds to DNS queries for configured subdomains based on keepalive status and balancing algorithms

5. Keeps a global view of server health by probing local SLBs such as the CSS/CSM/ACE

Someone from Cisco can verify if DD is EOL or not .I dont see it in the EOL products list at

http://www.cisco.com/en/US/products/prod_end_of_life.html

As per the feature navigator its still availabe as a feature of IOS image

http://tools.cisco.com/ITDIT/CFN/jsp/index.jsp

1. Select "search by feature"

2. Select "Distributed Director" under "Available Feature". It will give you a list of IOS Images supporting this feature.

Syed Iftekhar Ahmed

Ahmed Shahzad Mon, 07/28/2008 - 01:31

Please correct my understanding:

1. GSS can work as DNS Server to respond DNS queries other than domains defined in GSS?

2. GSS have multiple load balancing methods while DD have none. DD provide load balancing on the basis of Network Proximity.

3. DD take decision on layer 3 while GSS can monitor till layer 4.

4. GSS can provide DDoS mitigation while DD have no such mechanism.

Muhammad Ahmed Shahzad.

Syed Iftekhar Ahmed Mon, 07/28/2008 - 02:09

1. GSS can work as DNS Server to respond DNS queries other than domains defined in GSS?

To make it a full fledge DNS server you need Cto enable CNR (a licensed feature). Without CNR it only serves A records for the delegated domains.

2. GSS have multiple load balancing methods while DD have none. DD provide load balancing on the basis of Network Proximity.

Yup.

With each DNS query DD

makes a DRP query to each of the DRP servers, and compares the metrics returned to select the server that is closest to the client.

Where as with GSS you have around 10 GSLB methods available.

3. DD take decision on layer 3 while GSS can monitor till layer 4.

DD's decision making was mostly based on DRP & BGP

4. GSS can provide DDoS mitigation while DD have no such mechanism.

Even for GSS its comaparitively a new feature.

It doesnt come with the std code.You need additional Licences to activate it.

Ahmed Shahzad Mon, 07/28/2008 - 02:33

First of all thanks Iftikhar for quick replies.

I have three Data Center each is equiped with two GSS. Only one Data Center will be active at one time and will be switched over to second Data Center while the application server is not responding. Simialary it will switched to third Data Center while the applicaiton of first and second Data Center is not responding. Ordered List balance method would be used for this purpose or some one else?

How the GSS communicates with SLB; would it need extra configuration?

Syed Iftekhar Ahmed Mon, 07/28/2008 - 09:34

Yes Using ordered list you can achieve your desired results.

Each GSS independently probes the VIPs configured on local SLB devices. GSS can use

simple probes (like icmp, TCP, HTTP HEAD) to check the availability of the apps or can use Advance probes (KAL-AP /SNMP) to check the load along with the avialability. KAL-AP is the optimal method that works with the cisco SLB devices (CSS/CSM/ACE).It can check status of all VIPs configured on Cisco local SLB with a single query. SNMP probe is useful in case of non-cisco SLBs.

In case of KAL-AP you need some config changes on local SLB devices. For simple probes you dont need any special config on SLB devices (Apart from allowing the probe traffic).

HTH

Syed Iftekhar Ahmed

Ahmed Shahzad Mon, 07/28/2008 - 21:23

Thanks Iftekhar once again.

Yes it is Cisco ACE. Do you have a link showing sample configuration on ACE with KAL-AP.

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