Lab MPLS with Traffic Engineering

Name: Lab MPLS with Traffic Engineering
Uploaded: 2017-08-26T06:35:57+00:00
Duration: PTM29S19
Channel: Dominick Tennant
Description: Lab MPLS with Traffic Engineering

Lab MPLS with Traffic Engineering
Last Update 1.0.0 Copyright 2011 Kenneth M. Chipps Ph.D.

Copyright 2011 Kenneth M. Chipps Ph.D. www.chipps.com
Source This lab was developed by ibarrere That is the only name listed on the site It is found in a blog post from May 2009 on the web site at This looks like a very useful site Copyright 2011 Kenneth M. Chipps Ph.D.

What is MPLS MPLS is the next development in privately managed shared networks Large networks have migrated from dedicated T carrier circuits directly connecting sites to each other, to the first shared service provider network based on Frame Relay, to now MPLS MPLS uses tunnels between sites to carry traffic needing different types of QoS Copyright 2011 Kenneth M. Chipps Ph.D.

What is MPLS The source work on MPLS is defined in RFC 3031 MPLS flows are connection-oriented and packets are routed along paths pre-configured by service providers called LSP - Label Switched Paths Copyright 2011 Kenneth M. Chipps Ph.D.

What is MPLS Basic MPLS has been extended with a set of Generalized MPLS extensions that allow it to handle different types of traffic between the same general end points Copyright 2011 Kenneth M. Chipps Ph.D.

Operation of MPLS Metaswitch provides an excellent discussion and graphic to show how MPLS works They say MPLS works by tagging the traffic, in this example packets, with an identifier, a label, to distinguish the LSPs Copyright 2011 Kenneth M. Chipps Ph.D.

Operation of MPLS When a packet is received, the router uses this label and sometimes also the link over which it was received to identify the LSP It then looks up the LSP in its own forwarding table to determine the best link over which to forward the packet, and the label to use on this next hop A different label is used for each hop, and it is chosen by the router or switch performing the forwarding operation Copyright 2011 Kenneth M. Chipps Ph.D.

Operation of MPLS This allows the use of very fast and simple forwarding engines, which are often implemented in hardware Ingress routers at the edge of the MPLS network classify each packet potentially using a range of attributes, not just the packet's destination address, to determine which LSP to use Copyright 2011 Kenneth M. Chipps Ph.D.

Operation of MPLS Cisco also says This label is placed between the data link layer header and network layer The top of the label stack appears first in the packet, and the bottom appears last The network layer packet immediately follows the last label in the label stack Copyright 2011 Kenneth M. Chipps Ph.D.

LDP Traffic Capture File
Let’s look at some of these frames Download LDP and RSVP.cap Start Wireshark by double-clicking on the file Expand all of frame 1 Copyright 2011 Kenneth M. Chipps Ph.D.

This is a LDP Hello frame Notice the destination is the multicast address This is the all routers address In other words, who’s out there In frame 6 we see a LDP Hello from the other end of the link at Copyright 2011 Kenneth M. Chipps Ph.D.

Types of MPLS Links There are many types of MPLS connections to a service provider’s MPLS network For example, ATT supports MPLS connections through what they call IP VPNs As they say Copyright 2011 Kenneth M. Chipps Ph.D.

Types of MPLS Links Network-based VPN Deployed on the AT&T global network, which uses multiprotocol level switching (MPLS) to provide high-performance, any-to-any communication around the globe Copyright 2011 Kenneth M. Chipps Ph.D.

What is Traffic Engineering
Metaswitch says this about traffic engineering in MPLS networks Traffic Engineering is the process where data is routed through the network according to a management view of the availability of resources and the current and expected traffic The class of service and quality of service required for the data can also be factored into this process Copyright 2011 Kenneth M. Chipps Ph.D.

Traffic Engineering may be under the control of manual operators They monitor the state of the network and route the traffic or provision additional resources to compensate for problems as they arise Alternatively, Traffic Engineering may be driven by automated processes reacting to information fed back through routing protocols or other means Copyright 2011 Kenneth M. Chipps Ph.D.

Traffic Engineering helps the network provider make the best use of available resources, spreading the load over the layer 2 links, and allowing some links to be reserved for certain classes of traffic or for particular customers Copyright 2011 Kenneth M. Chipps Ph.D.

There are currently two label distribution protocols that provide support for Traffic Engineering RSVP - Resource ReSerVation Protocol CR-LDP - Constraint-based Routed Label Distribution Protocol Copyright 2011 Kenneth M. Chipps Ph.D.

MPLS and Traffic Engineering
MPLS and Traffic Engineering work together to provide tunnels that carry a certain class of service from one point to another Copyright 2011 Kenneth M. Chipps Ph.D.

MPLS in a Lab Environment
As it is difficult to create a real MPLS network in a lab environment and since simulation programs do not offer a MPLS cloud as they do for Frame Relay, this lab will use an emulation program In this case GNS3 running Dynagen which is controlling the Dynamips emulator How to use GNS3 is covered in detail in another presentation on this web site Copyright 2011 Kenneth M. Chipps Ph.D.

Lab Network Here is the lab network as setup in GNS3 To create the topology either Download and open this file in GNS3 MPLS With Traffic Engineering Lab.net or Lay the routers out as the diagram that follows shows Copyright 2011 Kenneth M. Chipps Ph.D.

Lab Network When the routers are placed be sure the labels match as well Next the modules to be added to the routers, which are all 7200 models Then the connections between the routers are made To simplify the setup the modules are all the same even though some of them are not actually needed in all the routers Copyright 2011 Kenneth M. Chipps Ph.D.

Configuration As the configurations are lengthy for this many routers they are provided as separate links to copy and paste txt files listed just below this lab’s link Download each one of these, then copy and paste the contents to each router based on the name of the file and the corresponding router Copyright 2011 Kenneth M. Chipps Ph.D.

RSVP Capture File Let’s open the same capture file We will see how RSVP did its work for us Go to frame 24 Expand all of the RSVP level Here the two ends are talking to each other in a path message over tunnel 2 As we can see there is a lot to say Copyright 2011 Kenneth M. Chipps Ph.D.

What Do The Commands Do Let’s look at some of the commands used to see what they do ip cef To turn on CEF – Cisco Express Forwarding This is required by Cisco routers doing tag switching of which label switching is a form As Cisco says CEF switching is a proprietary form of scalable switching intended to tackle the problems associated with demand caching Copyright 2011 Kenneth M. Chipps Ph.D.

What Do The Commands Do With CEF switching, the information which is conventionally stored in a route cache is split up over several data structures The CEF code is able to maintain these data structures in the Gigabit Route Processor The data structures that provide optimized lookup for efficient packet forwarding include It is on by default in some devices mpls traffic-eng tunnels Enables traffic engineering on the router Copyright 2011 Kenneth M. Chipps Ph.D.

What Do The Commands Do tunnel destination The IP address of the end of the tunnel Where the traffic is going tunnel mode mpls traffic-eng Specifies the encapsulation method for the tunnel In this case mpls Copyright 2011 Kenneth M. Chipps Ph.D.

What Do The Commands Do tunnel mpls traffic-eng autoroute announce This tells the routing protocol to consider the existences of the tunnel in its route calculations Otherwise the routing protocol will not send traffic through the tunnel If not this, then a static route will have to be used Copyright 2011 Kenneth M. Chipps Ph.D.

What Do The Commands Do tunnel mpls traffic-eng priority 2 2 This configures the setup and reservation priority for the tunnel The first number is the priority The second is the hold The numbers are the same tunnel mpls traffic-eng bandwidth 158 This is the bandwidth of the tunnel in kibps The range is 1 to Copyright 2011 Kenneth M. Chipps Ph.D.

What Do The Commands Do tunnel mpls traffic-eng path-option 1 explicit name BOTTOM This sets up a path option for the tunnel In this case the path is an IP explicit path related back to the tunnel destination The path is also in this case given a name no routing dynamic To prevent routing updates being sent through the tunnel They still go out, just not through the tunnel Copyright 2011 Kenneth M. Chipps Ph.D.

What Do The Commands Do mpls ip Enables the router to perform forwarding of MPLS labels in IPv4 packets along normally routed paths mpls traffic-eng tunnels Sets up MPLS traffic engineering for an interface Copyright 2011 Kenneth M. Chipps Ph.D.

What Do The Commands Do ip rsvp bandwidth Specifies how much bandwidth can be used by traffic engineering ip rsvp resource-provider none To enable or in this case disable any resource-provider, in other words a quality of service setting, for aggregate flow Aggregate flow refers to the traffic and its corresponding QoS requirements Copyright 2011 Kenneth M. Chipps Ph.D.

What Do The Commands Do mpls ldp autoconfig area 0 This command is to ease the configuration of LDP for the routing protocol Without it all of the interfaces would have to be setup one by one for LDP LDP is the Label Distribution Protocol mpls traffic-eng router-id Loopback0 This tells us the router identifier for the node is the IP address of that interface Copyright 2011 Kenneth M. Chipps Ph.D.

What Do The Commands Do mpls traffic-eng area 0 When OSPF is the routing protocol this configures the router to flood traffic engineering for the specified OSPF area Copyright 2011 Kenneth M. Chipps Ph.D.

What Do The Commands Do ip explicit-path name BOTTOM enable Specifies an explicit path name or number Enables that path The commands that follow detail the path or paths Such as next-address next-address Bottom or top forces traffic though a specific path Copyright 2011 Kenneth M. Chipps Ph.D.

MPLS with Traffic Engineering
As we can see when compared to the basic MPLS configuration this one is much more complex But MPLS with traffic engineering is the main point to MPLS, therefore a configuration along these lines is called for Copyright 2011 Kenneth M. Chipps Ph.D.

Lab MPLS with Traffic Engineering

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