© 2006 Cisco Systems, Inc. All rights reserved. MPLS v MPLS Concepts Identifying MPLS Applications
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v Outline Overview What Applications Are Used with MPLS? What Is Unicast IP Routing? What Is Multicast IP Routing? What are MPLS VPNs? What Is MPLS TE What Is MPLS QoS? What is AToM? What Are the Interactions Between MPLS Applications? Summary
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v MPLS Applications MPLS is already used in many different applications: –Unicast IP routing –Multicast IP routing –MPLS TE –QoS –MPLS VPNs (course focus) –AToM
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v MPLS Unicast IP Routing Basic MPLS service supports unicast IP routing. MPLS unicast IP routing provides enhancement over traditional IP routing. –The ability to use labels for packet forwarding: Label-based forwarding provides greater efficiency. The FEC corresponds to a destination address stored in the IP routing table. Labels support connection-oriented services. –The capability to carry a stack of labels assigned to a packet: Label stacks allow implementation of enhanced applications.
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v MPLS Multicast IP Routing MPLS can also support multicast IP routing: –A dedicated protocol is not needed to support multicast traffic across an MPLS domain. –Cisco Protocol Independent Multicast Version 2 with extensions for MPLS is used to propagate routing information and labels. –The FEC is equal to a destination multicast address stored in the multicast routing table.
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v MPLS VPNs MPLS VPNs are highly scaleable and support IP services such as: –Multicast –Quality of QoS –Telephony support within a VPN –Centralized services including content and web hosting to a VPN Networks are learned via an IGP from a customer or via BGP from other MPLS backbone routers. Labels are propagated via MP-BGP. Two labels are used: –The top label points to the egress router. –The second label identifies the outgoing interface on the egress router or a routing table where a routing lookup is performed. FEC is equivalent to a VPN site descriptor or VPN routing table.
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v MPLS TE MPLS TE supports constraints-based routing MPLS TE enables the network administrator to –Control traffic flow in the network –Reduce congestion in the network –Make best use of network resources MPLS TE requires OSPF or ISIS with extensions to hold the entire network topology in their databases. OSPF and IS-IS should also have some additional information about network resources and constraints. RSVP is used to establish TE tunnels and to propagate labels.
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v MPLS QoS MPLS QoS provides differentiated types of service across an MPLS network. MPLS QoS offers : –Packet classification –Congestion avoidance –Congestion management. MPLS QoS is an extension to unicast IP routing that provides differentiated services. Extensions to LDP are used to propagate different labels for different classes. The FEC is a combination of a destination network and a class of service.
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v Any Transport over MPLS AToM transports Layer 2 traffic over an IP or MPLS backbone. AToM accommodates many types of Layer 2 frames, including Ethernet, Frame Relay, ATM, PPP, and HDLC. AToM enables connectivity between existing data link layer (Layer 2) networks by using a single, integrated, packet-based network infrastructure. AToM forwarding uses two-level labels. AToM also offers performance, scalability, and other MPLS enhancements such as TE, fast reroute, and QoS.
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v Examples of AToM Ethernet over MPLS (EoMPS) –Supports the transport of Ethernet frames across an MPLS core for a particular Ethernet or virtual LAN (VLAN) segment –Applications include TLS and VPLS ATM over MPLS –Supports two types of transport mechanisms of ATM frames across an MPLS core: AAL5-over-MPLS mode Cell-relay mode Frame Relay over MPLS –Supports transport of Frame Relay packets over MPLS core –Carries BECN, FECN, DE, and C/R in a control word header
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v Interactions Between MPLS Applications
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v Summary MPLS is used in many applications: unicast IP routing, multicast IP routing, MPLS VPNs, MPLS TE, QoS, and AToM. Basic MPLS provides unicast IP routing using an IP routing protocol and a label distribution protocol. MPLS multicast IP routing does not need a dedicated protocol to support multicast traffic across an MPLS domain. MPLS VPNs provide highly scaleable VPNs providing IP services. MPLS TE supports constraints-based routing. MPLS QoS extends unicast IP routing and provides differentiated services. AToM transports Layer 2 traffic over an IP or MPLS backbone. Some MPLS applications may use a different routing and label exchange protocol; however, the applications all use the same label-forwarding engine.
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v