MPLS Basic Traffic Engineering Using OSPF Configuration Example
Introduction
This document provides a sample configuration for implementing traffic engineering (TE) on top of an existing Multiprotocol Label Switching (MPLS) network using Frame Relay and Open Shortest Path First (OSPF). Our example implements two dynamic tunnels (automatically set up by the ingress Label Switch Routers [LSR]) and two tunnels that use explicit paths.
TE is a generic name corresponding to the use of different technologies to optimize the utilization of a given backbone capacity and topology.
MPLS TE provides a way to integrate TE capabilities (such as those used on Layer 2 protocols like ATM) into Layer 3 protocols (IP). MPLS TE uses an extension to existing protocols (Intermediate System-to-Intermediate System (IS-IS), Resource Reservation Protocol (RSVP), OSPF) to calculate and establish unidirectional tunnels that are set according to the network constraint. Traffic flows are mapped on the different tunnels depending on their destination.
Functional Components
IP tunnel interfaces
Layer 2: an MPLS tunnel interface is the head of a Label Switched Path (LSP). It is configured with a set of resource requirements, such as bandwidth and priority. Layer 3: the LSP tunnel interface is the head-end of a unidirectional virtual link to the tunnel destination.
RSVP with TE extension
RSVP is used to establish and maintain LSP tunnels based on the calculated path using PATH and RSVP Reservation (RESV) messages. The RSVP protocol specification has been extended so that the RESV messages also distribute label information.
Link-State Interior Gateway Protocol (IGP) [IS-IS or OSPF with TE extension]
Used to flood topology and resource information from the link management module. IS-IS uses new Type-Length-Values (TLVs); OSPF uses type 10 Link-State Advertisements (also called Opaque LSAs).
MPLS TE path calculation module
Operates at the LSP head only and determines a path using information from the link-state database.
MPLS TE link management module
At each LSP hop, this module performs link call admission on the RSVP signaling messages, and bookkeeping of topology and resource information to be flooded by OSPF or IS-IS.
Label switching forwarding
Basic MPLS forwarding mechanism based on labels.
Network Diagram
Quick Configuration Guide
You can use the following steps to perform a quick configuration. Refer to MPLS Traffic Engineering and Enhancements for more detailed information.
Set up your network with the usual configuration. (In this case, we used Frame Relay.)
Note: It is mandatory to set up a loopback interface with an IP mask of 32 bits. This address will be used for the setup of the MPLS network and TE by the routing protocol. This loopback address must be reachable via the global routing table.
Set up a routing protocol for the MPLS network. It must be a link-state protocol (IS-IS or OSPF). In the routing protocol configuration mode, enter the following commands:
For IS-IS:
For OSPF:
LoopbackN (must have a 255.255.255.255 mask)Enable MPLS TE. Enter ip cef (or ip cef distributed if available in order to enhance performance) in the general configuration mode. Enable MPLS (tag-switching ip) on each concerned interface. Enter mpls traffic-engineering tunnel to enable MPLS TE.
Enable RSVP by entering ip rsvp bandwidth XXX on each concerned interface.
Set up tunnels to be used for TE. There are many options that can be configured for MPLS TE Tunnel, but the tunnel mode mpls traffic-eng command is mandatory. The tunnel mpls traffic-eng autoroute announce command announces the presence of the tunnel by the routing protocol.
Note: Do not forget to use ip unnumbered loopbackN for the IP address of the tunnel interfaces.
This configuration shows two dynamic tunnels (Pescara_t1 and Pescara_t3) with different bandwidth (and priorities) going from the Pescara router to the Pesaro router, and two tunnels (Pesaro_t158 and Pesaro_t159) using an explicit path going from Pesaro to Pescara.
...(略)
This document provides a sample configuration for implementing traffic engineering (TE) on top of an existing Multiprotocol Label Switching (MPLS) network using Frame Relay and Open Shortest Path First (OSPF). Our example implements two dynamic tunnels (automatically set up by the ingress Label Switch Routers [LSR]) and two tunnels that use explicit paths.
TE is a generic name corresponding to the use of different technologies to optimize the utilization of a given backbone capacity and topology.
MPLS TE provides a way to integrate TE capabilities (such as those used on Layer 2 protocols like ATM) into Layer 3 protocols (IP). MPLS TE uses an extension to existing protocols (Intermediate System-to-Intermediate System (IS-IS), Resource Reservation Protocol (RSVP), OSPF) to calculate and establish unidirectional tunnels that are set according to the network constraint. Traffic flows are mapped on the different tunnels depending on their destination.
Functional Components
IP tunnel interfaces
Layer 2: an MPLS tunnel interface is the head of a Label Switched Path (LSP). It is configured with a set of resource requirements, such as bandwidth and priority. Layer 3: the LSP tunnel interface is the head-end of a unidirectional virtual link to the tunnel destination.
RSVP with TE extension
RSVP is used to establish and maintain LSP tunnels based on the calculated path using PATH and RSVP Reservation (RESV) messages. The RSVP protocol specification has been extended so that the RESV messages also distribute label information.
Link-State Interior Gateway Protocol (IGP) [IS-IS or OSPF with TE extension]
Used to flood topology and resource information from the link management module. IS-IS uses new Type-Length-Values (TLVs); OSPF uses type 10 Link-State Advertisements (also called Opaque LSAs).
MPLS TE path calculation module
Operates at the LSP head only and determines a path using information from the link-state database.
MPLS TE link management module
At each LSP hop, this module performs link call admission on the RSVP signaling messages, and bookkeeping of topology and resource information to be flooded by OSPF or IS-IS.
Label switching forwarding
Basic MPLS forwarding mechanism based on labels.
Network Diagram
Quick Configuration Guide
You can use the following steps to perform a quick configuration. Refer to MPLS Traffic Engineering and Enhancements for more detailed information.
Set up your network with the usual configuration. (In this case, we used Frame Relay.)
Note: It is mandatory to set up a loopback interface with an IP mask of 32 bits. This address will be used for the setup of the MPLS network and TE by the routing protocol. This loopback address must be reachable via the global routing table.
Set up a routing protocol for the MPLS network. It must be a link-state protocol (IS-IS or OSPF). In the routing protocol configuration mode, enter the following commands:
For IS-IS:
metric-style [wide both]
mpls traffic-eng router-id LoopbackN
mpls traffic-eng [level-1 level-2]For OSPF:
mpls traffic-eng area X
mpls traffic-eng router-idLoopbackN (must have a 255.255.255.255 mask)Enable MPLS TE. Enter ip cef (or ip cef distributed if available in order to enhance performance) in the general configuration mode. Enable MPLS (tag-switching ip) on each concerned interface. Enter mpls traffic-engineering tunnel to enable MPLS TE.
Enable RSVP by entering ip rsvp bandwidth XXX on each concerned interface.
Set up tunnels to be used for TE. There are many options that can be configured for MPLS TE Tunnel, but the tunnel mode mpls traffic-eng command is mandatory. The tunnel mpls traffic-eng autoroute announce command announces the presence of the tunnel by the routing protocol.
Note: Do not forget to use ip unnumbered loopbackN for the IP address of the tunnel interfaces.
This configuration shows two dynamic tunnels (Pescara_t1 and Pescara_t3) with different bandwidth (and priorities) going from the Pescara router to the Pesaro router, and two tunnels (Pesaro_t158 and Pesaro_t159) using an explicit path going from Pesaro to Pescara.
...(略)
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