[j-nsp] Confusing terminology for LSPs in Junos

[John Neiberger]

I just took a Juniper MPLS and VPNs course and I have a question about the
ingress and egress types of LSPs. The terminology makes zero sense to me.
The LSP that is used to send traffic is called the ingress LSP, and the LSP
used to receive traffic is an egress LSP. How in the heck does that make
any sense? It seems exactly backwards. From the perspective of the router,
why would egress traffic leave on the ingress LSP and vice versa?

This seems really odd, but I presume there must be a really good reason for
it.

John