Chapter 5. Advanced MPLS Topics

Up until this point, this book has concentrated on explaining the concepts and mechanisms that make up the Multiprotocol Label Switching (MPLS) architecture. This chapter aims to provide further information on some more advanced topics that you face when deploying this architecture.

The guidelines presented in this chapter are specific to the MPLS architecture and are relevant to any deployment, regardless of whether advanced features, such as VPN, are used within the infrastructure. You can find further guidelines that are important for the successful deployment of the MPLS/VPN architecture in Chapter 13, "Guidelines for the Deployment of MPLS/VPN."

You have seen already how MPLS labels are distributed between adjacent TDP/LDP neighbors. However, it might be necessary to restrict the distribution of this information to certain neighbors, or even to block the advertisement of the information altogether. This chapter looks at this facility and analyzes why this feature can be useful when deploying MPLS. This chapter also looks at how the Cisco Systems, Inc., implementation of the MPLS architecture can deal with large packets across certain types of media that have a maximum transmission unit (MTU) that does not allow the addition of MPLS labels, by default, to packets that are larger than 1500 bytes.

Last, this chapter analyzes how MPLS can detect and prevent forwarding loops, and determines how aggregation of IP routing information can affect the functionality of the network.