Forum Discussion
Dave_W__178431
Nimbostratus
NimbostratusGTM Wildcard Listener
I'm trying to nail down the concept of the GTM's wildcard listener. Creating a listener (non-wildcard) causes a VS to be created for the listener's IP addresss. This virtual server then becomes another IP node on the network from the perspective of other devices on the network. Makes sense. Now, what happens when I configure a wildcard listener? Is the behavior such that entering a wildcard listener of 0.0.0.0 causes the GTM to start to answer ARP traffic for all addresses on attached subnets (even those IPs it doesn't own) or create a ton a virtual listeners? Both of those sound like bad scenarios, which is the reason for the question. What situation is the wildcard listener typically used for and what's the expected behavior when configured?
Thanks, Dave
Network listeners in both LTM and GTM by default do not participate in ARP. For wildcard/network listeners to work and not participate in ARP, the traffic must be routing through the BigIP for the BigIP to process it. In the GTM perspective you could have your GTM setup as the default gateway for your LDNS servers so when they perform recursion you could cache responses, use iRules, and respond authoritative if you wish.
Brad_Parker_139Nacreous
Network listeners in both LTM and GTM by default do not participate in ARP. For wildcard/network listeners to work and not participate in ARP, the traffic must be routing through the BigIP for the BigIP to process it. In the GTM perspective you could have your GTM setup as the default gateway for your LDNS servers so when they perform recursion you could cache responses, use iRules, and respond authoritative if you wish.
Dave_W__178431Brad, thanks for your reply. It seems that the wildcard listener feature has a limited use case. Could it also be used in a conserving subnet address use case? More specifically, can it be said that creating a wildcard listener can eliminate the need to create virtual servers (done by defautlt) per-listener and instead allow the GTM to use its self-IPs as listener IPs?
Brad_ParkerCirrus
Network listeners in both LTM and GTM by default do not participate in ARP. For wildcard/network listeners to work and not participate in ARP, the traffic must be routing through the BigIP for the BigIP to process it. In the GTM perspective you could have your GTM setup as the default gateway for your LDNS servers so when they perform recursion you could cache responses, use iRules, and respond authoritative if you wish.
- Dave_W__178431Brad, thanks for your reply. It seems that the wildcard listener feature has a limited use case. Could it also be used in a conserving subnet address use case? More specifically, can it be said that creating a wildcard listener can eliminate the need to create virtual servers (done by defautlt) per-listener and instead allow the GTM to use its self-IPs as listener IPs?