GTM sending data to VIP IP which is down.

How have you added the LTM VIP's (which is the VS is the GTM Pool) in the GTM Pool. Are you adding it as Generic host or under Iquery.

And when you said the VIP Is down on the LTM, is the GTM marking it as UP. The LTM VIP would have passed the tcp handshake from the GTM hence it would've marked it as UP. If you can post your GTM level configuration and the LTM VIP which is down. Can give you detailed solution.

But here's what I think you have, Your VIP2 is down and it has http profiles. But on the GTM pool, you have added the VS with basic tcp half open. So the GTM will mark it as UP. Because the tcp handshake gets successful to the VIP. Only when the next HTTP GET request is sent, the traffic would fail. So its not wrong the GTM marking it down. Hope it clarifies.

ok..can i use normal gateway icmp health monitor to check the VIP is UP or not. in that case if any VIP goes down the GTM will not transfer data to LTM, Am i right?

The VIP will always reply to icmp. By default icmp is enabled for every VIP in the LTM. Use basic tcp_half_open to monitor if you do not have Iquery setup. Try something like below,

create gtm server 1.1.1.1 datacenter "INDIA" monitor tcp_half_open addresses add { 1.1.1.1 } product generic-host virtual-servers add { 1_1_1_1_80 { destination 1.1.1.1:80 monitor tcp_half_open } }
create gtm server 2.2.2.2 datacenter "INDIA" monitor tcp_half_open addresses add { 2.2.2.2 } product generic-host virtual-servers add { 2_2_2_2_80 { destination 2.2.2.2:80 monitor tcp_half_open } }

create gtm pool test_pool load-balancing-mode round-robin verify-member-availability enabled ttl 30 members add { 1.1.1.1:1_1_1_1_80 }
create gtm pool test_pool_2 load-balancing-mode round-robin verify-member-availability enabled ttl 30 members add { 2.2.2.2:2_2_2_2_80 }

create gtm wideip test.wideip.com ipv6-no-error-response enabled pool-lb-mode round-robin pools add { test_pool { order 1 } test_pool_2 { order 0 } }