I'm working with a customer that is severely constrained with regard to availability of public IP's. They would like to external users to be load balanced to one of two resources, however, they only have one public IP to work with. Does anyone have any ideas or suggestions on how to accomplish this?

You must have 2 public IP addresses for DNS/GTM balancing. What you're asking for is not possible by any means. One option worth a consideration is opting for IPv6 on the external client-side, and continuing with IPv4 on the internal server-side. Most ISPs are freely handing out /64 IPv6 blocks.

if the customer comes up with two public IP's as required, would it be possible to use these for multiple services? Let's say that each address resolves to a "master VIP" in each data center that parses the URI and load balances the request to the appropriate service pool in each data center via an iRule.

GTM - minimizing public IP usage?

10 Replies

Hannes_Rapp_162
Nacreous
Jul 06, 2016
You must have 2 public IP addresses for DNS/GTM balancing. What you're asking for is not possible by any means.

One option worth a consideration is opting for IPv6 on the external client-side, and continuing with IPv4 on the internal server-side. Most ISPs are freely handing out /64 IPv6 blocks.
- eatstmanpdx_205
  Nimbostratus
  Jul 06, 2016
  if the customer comes up with two public IP's as required, would it be possible to use these for multiple services? Let's say that each address resolves to a "master VIP" in each data center that parses the URI and load balances the request to the appropriate service pool in each data center via an iRule.
- DevBabu
  Cirrus
  Jul 06, 2016
  Yes.
- Hannes_Rapp_162
  Nacreous
  Jul 06, 2016
  Yes that would be possible. You can re-use a given IP address for another service by using a different port number. You can also re-use an IP for another service by utilizing iRules or LTM policies which conditionally select various target pools, based on L7 request content (i.e. directing request to another pool if there's a match to a specific HTTP request Host, Path or URI value). All of this can be done in the LTM module.
Hannes_Rapp
Nimbostratus
Jul 06, 2016
You must have 2 public IP addresses for DNS/GTM balancing. What you're asking for is not possible by any means.

One option worth a consideration is opting for IPv6 on the external client-side, and continuing with IPv4 on the internal server-side. Most ISPs are freely handing out /64 IPv6 blocks.
- eatstmanpdx_205
  Nimbostratus
  Jul 06, 2016
  if the customer comes up with two public IP's as required, would it be possible to use these for multiple services? Let's say that each address resolves to a "master VIP" in each data center that parses the URI and load balances the request to the appropriate service pool in each data center via an iRule.
- DevBabu
  Cirrus
  Jul 06, 2016
  Yes.
- Hannes_Rapp
  Nimbostratus
  Jul 06, 2016
  Yes that would be possible. You can re-use a given IP address for another service by using a different port number. You can also re-use an IP for another service by utilizing iRules or LTM policies which conditionally select various target pools, based on L7 request content (i.e. directing request to another pool if there's a match to a specific HTTP request Host, Path or URI value). All of this can be done in the LTM module.