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Nokia VPN Services Tunnel Structure
In this lesson we will talk about the Tunnels used for VPN Services that is set up via MPLS (Multiprotocol Label Switching). Here there are some key points that you must know to understand VPN Service structure well.
Think about that. Physically we have one port. In services structure, there are Transport Tunnels that is set up via LDP or RSVP-TE. As you know LDP and RSVP-TE are the two protocols that are used in MPLS as label switching protocols. Shortly, Transport Tunnels are the tunnels in which the label switching is done with Transport Labels. This is the Outher Label of the VPN packet. LSPs (Label Swithed Paths) are set up with these protocols.
Here, it is important to define something about TLDP. TLDP sessions are the the LDP sessions that is between non directly connected peers.
We can sum up the network signaling below. Think about the service provider core. There are PE routers at the edges and P routers in the middle. Between the PE routers the below steps must be done for all the routers.
- An IGP is used between all the routers. This is for the reachability.
- LDP or RSVP-TE is used to signal the Transport Labels. After the convergence of the LDP of RSVP-TE ans LSP is created.
- TLDP or MP-BGP is used to signal the Service Labels. By doing this, it identifies each VPN Service.