[j-nsp] ifl and ifd list

[Phil Shafer]

Shiva Shankar writes:
>Hi All, I was going through some commands and cos related statistics for in
>shell more. I can see most of the time IFL is associated with cos related
>statistics...Is there any documentation which explains the relation with IFD
>and IFL and how they are used to interact?

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].

    interfaces {
        so-1/2/3 {                        /* ifd */
            unit 0 {                      /* ifl */
                family inet {             /* iff */
                    address 10.1.2.3/24 { /* ifa */
                        primary;
    }   }   }   }   }

We use the convention {device}.{unit} elsewhere in the config for
an ifl (like so-1/2/3.0) and the unit defaults to zero, so "set
so-1/2/3" is expanded to become "so-1/2/3.0".  We also expand
"so-1/2/3.0" to "so-1/2/3 unit 0" where appropriate.  These are
done for user convenience, but admittedly may be increasing your
confusion.  Pseudo interfaces, channelized interfaces, and other
advanced PICs add to the confusion and layering issues.

Hope this helps.

Thanks,
 Phil