Forum Discussion
9 Replies
- Jason_40733Cirrocumulus
The GTM feature uses DNS to re-direct traffic. You can set it up to monitor health of the servers behind it. You can also have it set one set of servers as the primary, and the other as backup.
You'll need to tune your DNS record TTL appropriately though. If you go with a 24 hour TTL of 86400... the GTMs would immediately start serving out the Data Recovery Center IP address right away when the Data Center is unavailable, but anyone that has connected will have the old IP address cached for the next 24 hours. If you tune your DNS TTL down to 0... you'll be serving out the IP address from your GTM's on every single request. This is doable, but doesn't scale for large environments.
Jason
- Kibao_130897NimbostratusThanks Very Much Jason, What do you mean when you say large environments? We have 214 sites and each site has around 20 users. Will this solution work perfect with our infrastructure? Saidi
- Jason_40733CirrocumulusTurning your DNS TTL for things being load balanced by GTM means that every connection from every client will always do a DNS lookup. If you have a very busy application or one that does not make use of persistent connections you can flood your GTMs with DNS requests by setting the TTL to 0. Determining an acceptable amount of "lag" between switching from a failed primary to a backup and then setting your DNS TTL appropriately is advised. I've had some applications that useda 300 second TTL, and some that used a 10 second TTL. Jason
- Kibao_130897Nimbostratus
Thanks Very Much Jason,
What do you mean when you say large environments? We have 214 sites and each site has around 20 users. Will this solution work perfect with our infrastructure?
Saidi
- TechgeeegNimbostratus
Hi Kibao,
How your remote sites connects to your DC is it over the internet with some sort of VPN to the main site also what are the services that the users on remote site access is it all web based services or different??
Regards,
- Kibao_130897NimbostratusCurrently all remote sites connects to the DC through VPN connection over the WAN but later there will be some sites which will connect to the DC over the internet. All users access DC services via web based services
- Techgeeeg_28888Nimbostratus
Hi Kibao,
How your remote sites connects to your DC is it over the internet with some sort of VPN to the main site also what are the services that the users on remote site access is it all web based services or different??
Regards,
- Kibao_130897NimbostratusCurrently all remote sites connects to the DC through VPN connection over the WAN but later there will be some sites which will connect to the DC over the internet. All users access DC services via web based services
- Jason_40733Cirrocumulus
With respect to your 214 sites and 20 users. It will depend on the application and how it does requests. 4280 users is not a lot for doing DNS requests even concurrently. It is unlikely your application is written poorly enough to overwhelm your GTM even with a TTL of 0.
Anycast may also be a different non-GTM solution for you. Compare the two and choose the one that best fits your needs.
Jason