An LDP-MPLS is deployed on a network and labels are used for packet forwarding. As you may know, LDP needs IGP and there is IGP too. Because there is no RSVP, there is no traffic engineering and there is no bandwidth reservation.

Rather than "locally" looking-up tables which reduces the look-up process load for packet forwarding (and I think this look-up process is no load for today routers), What are other advantages for using LDP-MPLS? In comparison to using just IGP like OSPF for the network.

P.S. This link didn't help.

  • IGP is no defined protocol. It's a class of protocols used for interior gateway exchange - like OSPF, IS-IS or EIGRP. In any case, you do require a routing protocol to exchange the routes. Static routing doesn't work with LDP. Note that any routing protocol just updates the local routing tables that are then used to direct the traffic.
    – Zac67
    Jul 18, 2021 at 18:17
  • @Zac67, I know that IGP is a protocol family name. I said that OSPF is running for example. I need a justification to use pure LDP. Is it reasonable? or an OSPF is sufficient for packet forwarding and there is no advantage for using LDP. manish ma mentioned that VPNs are one of the MPLS applications. I should do some research about VPNs to understand this MPLS application.
    – A.A
    Jul 19, 2021 at 9:00
  • That largely depends on what features you require and why you're actually considering MPLS...
    – Zac67
    Jul 19, 2021 at 9:39

1 Answer 1


In todays routers routing lookup is done in hardware, usually in TCAM, which is as fast as ILM lookup. So no advantage in lookup speed. So why is it even needed? For tunneling. If you want to deploy a full-mesh of tunnels dynamically between routers (usually PE routers) you can use LDP. This provides infrastructure for services like L3VPN, L2VPN etc.

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