Hey Folks, let’s get to the advance configuration of the MPLS on Cisco Platform, you are all already familiar for different types of configuration with the CE and PE, P Routers.

Here we will discuss the Concept of TE (Traffic Engineering) on MPLS and Flowchart to configure the MPLS TE. So let’s first see what is MPLS TE:

TE is the process of steering traffic across to the backbone to facilitate efficient use of available bandwidth between a pair of routers. Prior to MPLS TE, traffic engineering was performed either by IP or by ATM, depending on the protocol in use between two edge routers in a network. Though the term “traffic engineering” has attained popularity and is used more in the context of MPLS TE today, traditional TE in IP networks was performed either by IP or by ATM.

The main advantage of implementing MPLS TE is that it provides a combination of ATM’s TE capabilities along with the class of service (CoS) differentiation of IP. In MPLS TE, the headend router in the network controls the path taken by traffic to any particular destination in the network. The requirement to implement a full mesh of VCs, as in ATM, does not exist when implementing MPLS TE. Therefore, when MPLS TE is implemented.

Let’s follow below steps in order to have MPLS TE Working Properly: (Consists of 7 Steps)

  • Configuration of Loopbacks

Configure a loopback interface for tunnel association to the TE tunnel:

  • Enabling the MPLS (Global / Interface )

The next step is the first configuration performed in relevance to enabling TE on the Cisco router. The configurations performed on the Cisco router to enable TE functions globally on the router as well as interfaces that are possible candidates to be chosen for TE LSP paths.

  • Configure RSVP Bandwidth Parameters

Configure RSVP bandwidth parameters that will be used on the interface for signaling purposes and resource allocation for traffic engineered sessions. The configurations that need to be performed on the interface.

  • Configure Tunnel Interface Parameters

After the interfaces that can be chosen to be a part of the LSP have been enabled for TE as well as RSVP parameters configured, the next step is to configure the tunnel interface. The main configurations of the tunnel interface would be association of the tunnel interface IP address to the loopback address configured earlier, the mode of the tunnel operation, and the destination address of the tunnel endpoint, which would map to the IP address of a loopback on the tailend router as well as the process by which the tunnel LSP path is chosen. In this step, if the path chosen for the LSP is done using the IGP and CSPF, the path option is chosen to be dynamic.

  • Configure Exploit path parameters for user-defined tunnels (Optional)

In addition to using the IGP for LSP path setup, the user can also define an explicit-path that will be used for the TE LSP. This optional step can be performed on the headend router so that the dynamic tunnel can be chosen to be the tunnel of choice for traffic forwarding and the explicit-path tunnel or user-defined static tunnel can be the backup path. In some cases, load balancing can also be achieved between the two types.

  • Announce Tunnel Interface in IGP

By default, the tunnel interface is not announced into the IGP for use in the routing table. This will have to be configured explicitly for the tunnel interface to be used as the next hop in the routing table by the IGP. The configurations that will have to be performed on the headend router to enable tunnel interface use as the next-hop address in the routing table for TE.

  • Configure IGP for Traffic Engineering

The final step in the configuration of MPLS TE is the configuration of the IGP for TE support. The IGP in use can be either OSPF or IS-IS. The IGP process used for TE is the same as what’s defined for NLRI reachability. The configurations involved for enabling TE extensions for both these protocols.

In the scenario we have Six routers connected to each other and the Service Provider Patch is providing two paths for Client A to reach Client B, let’s start with the commands for above steps:

  • Step 1

PE1-AS1(config)#interface loopback 1
PE1-AS1(config-if)#ip address
*Jan 27 10:31:59.083: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to up
PE1-AS1(config-if)#ip address

  • Step 2

PE1-AS1(config)#mpls traffic-eng tunnels
PE1-AS1(config)#interface serial 1/0
PE1-AS1(config-if)#mpls traffic-eng tunnels

  • Step 3

PE1-AS1(config-if)#interface serial 1/0
PE1-AS1(config-if)#ip rsvp bandwidth 1000000 100000 ingress

  • Step 4

PE1-AS1(config)# interface tunnel 12
PE1-AS1(config-if)# ip unnumbered loopback 0
PE1-AS1(config-if)# tunne mode mpls traffic-eng
PE1-AS1(config-if)# tunnel destination
PE1-AS1(config-if)# tunnel mpls traffic-eng path-option 100 dynamic bandwidth 100000 lockdown
PE1-AS1(config-if)# tunnel mpls traffic-eng bandwidth 10000
PE1-AS1(config-if)# tunne mpls traffic-eng priority 1
PE1-AS1(config-if)# exit

  • Step 5

PE1-AS1(config)#ip explicit-path name MPLS-TE enable
PE1-AS1(config)#ip explicit-path identifier 10 enable
Explicit Path identifier 10:
1: next-address
Explicit Path identifier 10:
1: next-address
2: next-address
Explicit Path identifier 10:
1: next-address
2: next-address
3: next-address

  • Step 6

PE1-AS1(config-if)#interface tunnel 12
PE1-AS1(config-if)#tunnel mpls traffic-eng autoroute announce

  • Step 7

PE1-AS1(config)#router ospf 10
PE1-AS1(config-router)#network area 0
PE1-AS1(config-router)#mpls traffic-eng area 10
PE1-AS1(config-router)#mpls traffic-eng router-id tunnel 12

Next i will come up with the full and advance Traffic Engineering on top of MPLS, and i hope the current post help with the whole concept of the Traffic Engineering.


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