MPLS Fundamentals - Chapter 1 – Review Questions

1. What are the MPLS applications mentioned in this chapter?

- Traffic engineering

- MPLS VPNs

- AToM

 

2. Name three advantages of running MPLS in a service provider network.

- The use of one unified network infrastructure

- Better IP over ATM integration

- The core routers in the service provider network no longer need to run BGP.

- Adding one customer site means that on the PE router, only the peering with the CE router must be added. You do not have to hassle with creating many virtual circuits as with the overlay model or with configuring packet filters or route filters with the peer-to-peer VPN model over an IP network. This is the benefit of MPLS VPN for the service provider.

- As the operator of the MPLS-with-traffic-engineering-enabled network, you can steer the traffic from A to B over the bottom path, which is not the shortest path between A and B (four hops versus three hops on the top path).

- An extra advantage of running MPLS traffic engineering is the possibility of Fast ReRouting(FRR).

 

3. What are the advantages of the MPLS VPN solution for the service provider over all the other VPN solutions?

- The peer-to-peer VPN model demanded a lot from provisioning because adding one customer site demanded many configuration changes at many sites. MPLS VPN is one application of MPLS that made the peer-to-peer VPN model much easier to implement. Adding or removing a customer site is now easier to configure and thus demands much

less time and effort. With MPLS VPN, one customer router, called the customer edge (CE) router, peers at the IP Layer with at least one service provider router, called the provider edge (PE) router. Adding one customer site means that on the PE router, only the peering with the CE router must be added. You do not have to hassle with creating many virtual circuits as with the overlay model or with configuring packet filters or route filters with the peer-to-peer VPN model over an IP network. This is the benefit of MPLS VPN for the service provider.

 

4. Name the four technologies that can be used to carry IP over ATM.

- RFC 1483,"Multiprotocol Encapsulation over ATM Adaptation Layer 5"

- LAN Emulation (LANE).

- Multiprotocol over ATM (MPOA)

- MPLS on ATM

 

5. Name two pre-MPLS protocols that use label switching.

- Frame relay

- ATM

 

6. What do the ATM switches need to run so that they can operate MPLS?

- The ATM switches had to run an IP routing protocol and implement a label distribution protocol

 

7. How do you ensure optimal traffic flow between all the customer sites in an ATM or Frame Relay overlay network?

- Because the ATM or Frame Relay switches are purely Layer 2 devices, the routers interconnect through them by means of virtual circuits created between them. For any router to send traffic directly to any other router at the edge, a virtual circuit must be created between them directly. Creating the virtual circuits manually is tedious. In any case, if the requirement is the any-to-any connection between sites, it is necessary to have a full mesh of virtual circuits between the sites, which is cumbersome and costly. If the sites are only interconnected as in the traffic from CE1 to CE3 must first go through CE2.