Take a look at this explanation for these interfaces
http://forums.juniper.net/t5/Routing/Show-interface-terse-in-Juniper/td-p/302355
See this article understanding the interface requirements for vrrp
https://www.juniper.net/documentation/en_US/junos/topics/concept/vrrp-overview-ha.html
IRB Interfaces and RVI Functions and Other Technologies
IRB interfaces and RVIs are similar to switch virtual interfaces (SVIs) and bridge-group virtual interfaces (BVIs), which are supported on other vendors’ devices. They can also be combined with other functions:
- VRF is often used in conjunction with Layer 3 subinterfaces, allowing traffic on a single physical interface to be differentiated and associated with multiple virtual routers. For more information about VRF, see Understanding Virtual Routing Instances on EX Series Switches .
- For redundancy, you can combine an IRB interface or RVI with implementations of the Virtual Router Redundancy Protocol (VRRP) in both bridging and virtual private LAN service (VPLS) environments. For more information about VRRP, see Understanding VRRP on EX Series Switches.