While configuring I'm not getting any option to enable Gateway firewall on T1, then why I'm able to see this service?
### Did you configured Edge cluster on your T1 router in this example?
Because of this service will there be any Impact of VM Traffic flow?
### No, because it will hit Default rule which is actually PERMIT ALL.
Will T1 still be called as DR only?
### T1 can host stateful services also, which means SR component, beside DR. Will it host SR component depends on T1 configuration inside NSX.
How to disable this gateway firewall service on T1 gateway?
### If you attached Edge cluster at first point - try disabling it, which should remove SR service from T1 router.
HTH,
Dragan