Our team just started working on technology involving MPLS and stuff, so we were talking about MPLS networks, then came a question as to why do we always see loopback addresses in examples and is it like a strict requirement? We couldn’t find a solid answer or answers, owing to the fact that we are a bunch of security experts just landed into this MPLS
So the question is, Is it a must to have Loopback addresses for MPLS to work? Well, I got the following from [Here]
"Loopback" IP addressAlthough not a strict requirement, it is advisable to configure routers participating in MPLS network with "loopback" IP addresses (not attached to any real network interface) to be used by LDP to establish sessions. This serves 2 purposes:
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Is there any other reason that you think should be there? Would appreciate if you could comment.
Another reason is specific to Juniper (not sure about Cisco routes)
Juniper Routers (by default) advertises only loopback address as an FEC which allows all LDP routers in the network to establish an LSP to the loopback address of every
other router in the network. If loopback address is not configured then route id (lowest interface IP) with /32 prefix will be advertised as an FEC then receiving router will first try to locate reachbility to advertised FEC through IGP and obviously won’t find reachability as address is advertised with /32 prefix, as a result no LSP will be established.