I came across terms like IFL IFD and IFA 's recently when studying some articles related to my project, I dont clearly understand what they are and the difference between them. I know they are related to interfaces within networking devices. I came across these terms when studying article on Juniper network's website.
This juniper-nsp email explains them pretty clearly...
We try to avoid the terms "ifd" and "ifl" completely in our docs, but these internal terms have slipped out in a few places. The relationship is fairly simple: "ifd" is the physical interface device, where "ifl" is the logical interface (aka unit). Logical interfaces are arranged as children of a physical interface... As an example, [interfaces so-1/2/3] would be a physical interface and [interfaces so-1/2/3 unit 0] would be a logical unit. The organization hierarchy continues down with address families (iff) as [... family inet] and addresses (ifa) as [... address 10.1.2.3/24].
- ifd: A Junos Physical Interface
- ifl: A Junos Logical Interface (how individual vlans on a physical interface are distinguished)
- ifa: A Junos interface address