Greenfield MPLS Network Design Using SPGuru.doc

Subject: Greenfield MPLS Network Design Using SPGuru Date: From: 2013-4-10 Ahmet Akyamac Benjamin Tang Ramesh Nagarajan Advanced Technologies Bell Laboratories Holmdel, NJ07744 (732) 949-5413 (732) 949-6477 (732) 949-2761 [email protected] [email protected] [email protected] 1. Introduction & Scope SPGuru is a network design, capacity planning and traffic engineering tool offered by Opnet. It incorporates features that are of interest to LWS, such as network configuration, capacity planning, QoS analysis and simulation, etc. for a number of networking technologies such as ATM, IP and MPLS. This document focuses on the Greenfield topological design of MPLS networks using Opnet’s SPGuru. 1.1 Greenfield MPLS Network Design Overview The latest version of SPGuru as of the writing of this document is 11.0. SPGuru 11.0 supplied to Lucent Technologies contains a custom design feature called Min_Cost_MPLS_Net_Design. This feature represents a custom workflow that performs a near-optimal topological design for a Greenfield network given a set of input nodes, link cost tariffs and MPLS LSP demands. Please note that, as of version 11.0, the Min_Cost_MPLS_Net_Design feature does not different forwarding classes or classes of service (CoS). This document will be updated as this feature becomes available. The following figure represents the process of Greenfield MPLS network design using the Min_Cost_MPLS_Net_Design custom design feature in SPGuru: Input Node and Link Data Input LSP Requirements Greenfield Design Output Visualization Lucent Technologies Inc. - Proprietary Use pursuant to Company instructions. 1 The new window will show the new project. as shown in Figure 2.Proprietary Use pursuant to Company instructions. as shown in Figure 1. This is accomplished by selecting File->New from the SPGuru splash screen. 1. then design.). SPGuru allows for projects to consist of multiple scenarios. The zoom feature allows the Lucent Technologies Inc. we discuss the components of the above process using an example network and example screen captures from SPGuru.2 Node and Link Data Input The first step is to create a new project.In the following. it is recommended to split the different phases of a network design project into multiple scenarios. new scenario and the default world map background. it is not necessary to use the startup wizard to create a new scenario. 2 . etc. topology input. Figure 1: SPGuru splash screen Since we are interested in Greenfield design. A scenario management interface is also provided. In general. each representing the completion of a certain action (for example. The new project and scenario can now be saved under a custom file. then failure analysis. . thereby outlining the typical steps required to use SPGuru for Greenfield MPLS network design. These are found in the Juniper toolbox of the object palette. or manually using the SPGuru GUI. . China Unicom uses Juniper T640 routers. For our example. Object Palette icon Figure 2: Default view for a new project and scenario 1.2. 3 . the user has to select MPLS capable routers (LSR’s) from the object palette.Proprietary Use pursuant to Company instructions. the user can click on any Lucent Technologies Inc. Multiple zoom-in actions will eventually display the names of major cities. Once the T640 is selected. as seen in Figure 2. For manual node entry. we use examples from the China Unicom design study to illustrate node data input procedures.user to select different areas on the map. In the following. The first icon on the left of the icon bar can be used to access the object palette. as shown in Figure 3.1 Node Data Input Node data can be input either using configuration files from Cisco and Juniper routers. as shown in Figure 4. 4 . Figure 3: The Juniper toolbox of the object palette The attributes of the node can be edited by right clicking on the node icon on the map and selecting Edit Attributes. the model name was JN_T640_s3_a16_ge48_sl64).location(s) in the map to place T640 devices (for this example.Proprietary Use pursuant to Company instructions. . we will only change the names. For now. Multiple nodes can be entered into the map and right clicking will exit the entry mode. we chose the densely populated T640 of the two options shown while placing the device. Lucent Technologies Inc. we show a network imported using Juniper configlet files. . Figure 5: Network view after configlet import 1. or configlets. To import topologies using configlet files. In Figure 5. for Cisco and Juniper routers. which are not shown in this figure. we have removed the links (since we will be performing Greenfield design).Figure 4: Editing node attributes Node data can also be entered using configuration files.Proprietary Use pursuant to Company instructions. select Topology->Import Topology->From Device Configurations. and a section of the configlet file for the Beijing node. and specify the directories that contain the Cisco and Juniper configlet files. For this network. This network also contains a set of dynamic E-LSP’s.2 Link Data Input Lucent Technologies Inc. link speeds). and we have set all node models to JN_T640_s3_a16_ge48_sl64. 5 .2. Note that the configlet files do not contain information about the specific device model or interface speeds (hence. The link speeds and node models need to be manually entered. as of Release 11. The set of candidate links need to be placed in a custom object palette. Note that in SPGuru. . the capacity of a link is defined by its data rate. LSP data can be input either using configuration files from Cisco and Juniper routers.3 LSP Data Input As in the case of the node data input. 6 . Continuing with our China Unicom example. and save it under the name MPLS_MandP_Example_Custom_Link_Palette. For this design example. However. the next step is to add/delete link types in this palette. Once the LSP model is selected. A custom palette is created by opening the object palette. 1. a price can be associated with each link type in SPGuru. To manually enter LSP’s. These changes are made using the Configure Palette GUI and must be saved (overwritten) to MPLS_MandP_Example_Custom_Link_Palette.For Greenfield design using the Min_Cost_MPLS_Net_Design feature. selecting Configure Palette and saving an existing palette under a custom name (as a starting point for the custom palette). we will discuss link pricing in Section 1. For this example. not its transmission rate. Once a custom palette is created. the Min_Cost_MPLS_Net_Design feature incorporates a link cost model that overrides the individual price models for the candidate links. Figure 6: Custom link palette Since the Min_Cost_MPLS_Net_Design feature tariff model overrides the link price settings from the palette. the link data input consists of a set of candidate links and link pricing information.Proprietary Use pursuant to Company instructions. OC-12 and OC-48 links. select the MPLS_E-LSP_DYNAMIC model from the MPLS palette. or manually using the SPGuru GUI.61 Mbps.0. and a destination Lucent Technologies Inc. we initially select the pre-defined links palette as the starting point. we configured the custom palette as shown in Figure 6 to include DS3. by right clicking on each intermediate LSR to add it to the path). an OC-3 link has a capacity of 148. create LSP’s one by one by selecting a source LSR. Normally. we will enter dynamic E-LSP’s. intermediate LSR’s (if necessary.4. For example. . To create a pair of LSP’s. and specify the directories that contain the Cisco and Juniper configlet files (this process will import all topology information. The TE bandwidth is set to 10 Mbps. This can be done one by one while entering LSP’s. To import topologies using configlet files.LSR (right click and cancel add action when done). we need to only assign the traffic engineering (TE) minimum bandwidth for the LSP’s. or a bandwidth can be macro-edited on a group of selected LSP’s. Figure 7 shows the MPLS palette and manual entry of an E-LSP and the LSP attributes where the TE bandwidth can be set. Figure 7: Manual LSP entry As in the case of node data.and LSP’s). select Topology->Import Topology->From Device Configurations. LSP data can also be entered using configuration files. link topology-but not interface rates. or configlets. for Cisco and Juniper routers. a second LSP must be created in the opposite direction. it is necessary to “commit” LSP information by selecting Protocols>MPLS->Update LSP Details. 7 .Proprietary Use pursuant to Company instructions. including node locations. Since the Min_Cost_MPLS_Net_Design feature is meant for Greenfield design. apply the same process as before. This particular example is for an E-LSP from Xian to Shenyang with an intermediate hop at Guangzhou. Lucent Technologies Inc. Once all LSP’s are entered. Note that this creates a single LSP from source to destination. Of particular interest are the link cost options. we use the imported LSP requests and set the minimum TE bandwidth to 45 Mbps for each of them. and the resulting point-to-point LSP requests that are generated after the LSP information is updated. After LSP Import After LSP Update Figure 8: LSP entry by configlet import 1. Figure 9 shows the numerous options that can be configured for this design. the design action should be saved under a custom name. and the number of iterations and random cases. In Figure 8. 8 .After an import is complete. our design is called MPLS_MandP_Example_Design. under the Topology Design section (the Design->Run Design Action menu allows for fast access to the currently configured design actions but does not allow extensive editing and saving of the design parameters). we show the result of an import process containing LSP pairs. which we discuss below.Proprietary Use pursuant to Company instructions. Once the options are set. In our design example. This feature is accessed through Design->Configure/Run Design Action menu. the link price sub-action. Lucent Technologies Inc. Note that the candidate link palette is set to our custom link palette.4 Greenfield Design The Greenfield design is performed using the Min_Cost_MPLS_Net_Design feature. MPLS_MandP_Example_Custom_Link_Palette. the LSP information needs to be updated using Protocols->MPLS>Update LSP Details. so that all options can be saved for future use. . cost per distance and. This generates a customized link metric cost formula. 9 .Proprietary Use pursuant to Company instructions. the Min_Cost_MPLS_Net_Design feature overrides the link cost models associated with the link objects in the object palette.1. Figure 9: Min_Cost_MPLS_Net_Design feature options Lucent Technologies Inc. which is accessed through the Link_Pricer sub-action of the Min_Cost_MPLS_Net_Design feature. different tariff rates between given geographic locations (which requires the latitude and longitude information for the node locations). The second is a customized link financial cost (or tariff) interface. which requires a financial cost function. The first is through the Link Metric Information option in the design attributes. There are two components to specifying link cost. These cost calculations apply to all candidate links in the network and override the individual financial cost components defined in the object palette for the link objects. optionally. cost per data rate. . As mentioned earlier.4. This sub-action allows the user to specify financial cost as a combination of fixed cost.1 Link Cost Options The design will be influenced by the link costing method. The link metric is a function of the distance. These include the distance factor. financial cost and traffic.Figure 10: Link Metric Information parameters Figure 10 shows our chosen parameters for the Link Metric Information fields. Figure 11 details how the link metrics are calculated during the design: Lucent Technologies Inc. the metric of existing links can be discounted so that an existing link will be viewed cheaper (or free) during the design. . 10 . During the Greenfield design process. Additionally. cost (financial) factor.Proprietary Use pursuant to Company instructions. traffic factor and existing link discount factor. these factors determine the cost metric of candidate links. Taken from the interactive help option in SPGuru. c_raw = the raw cost value for a candidate link c_norm = 1. This includes direct traffic and traffic homed to the node pair. d_raw = the raw distance value for a candidate link d_norm = 1. 11 . distance based cost parameter.0 if d_raw > d_95 = d_raw/d_95 otherwise Used to normalize a raw distance value. As can be seen in Figure 13. data rate based cost parameter and a custom database based cost parameter.0 if t_raw > t_95 = 1 . plus $100 every km. t_norm = 0.t_raw/t_95 •The link metric is further discounted by the Existing Link Discount if there already exists a link between the node pair. and includes a fixed cost parameter. node pairs with high traffic. Figure 11: Link metric calculations using the Link Metric Information fields The parameters for the Link Price sub-action are shown in Figure 13. If the link exists. we saved our action as MandP_Example_link_pricer.. •c_95 = the 95% cost value over all candidate links considered. Used to normalize a raw traffic value. We did not include a custom tariff database for this design. but it is less than the required bandwidth. which is obtained from a custom tariff database file. More traffic results in a lower link cost metric in order to favor direct links between t_95 = the 95% traffic value over all candidate links considered.0 if c_raw > c_95 = c_raw/c_95 otherwise Used to normalize a raw cost value. The financial cost of the link is calculated as in Figure 12. we assumed a fixed cost of $1000 per link.•link_metric = distance_factor * d_norm + cost_factor * c_norm + traffic_factor * t_norm •d_95 = the 95% distance value over all candidate links considered. .Proprietary Use pursuant to Company instructions. t_raw = the raw maximum traffic value between a node pair in bps. Lucent Technologies Inc. •Traffic is inversely weighted. c_raw = custom_db_cost + fixed_cost + cost_per_kb * data_rate_in_kb + cost_per_km * distance_in_km Figure 12: Financial cost calculations For our design example. the discount is proportional to the amount of bandwidth that is already provided. and a cost per Kbps of $10. The specified link pricing sub-action can be saved for future access. .Figure 13: Link Pricer sub-action parameters Lucent Technologies Inc. 12 .Proprietary Use pursuant to Company instructions. The initial seed is specified as one of the options shown in Figure 9. This process is repeated until the number of iterations is exhausted. In subsequent iterations. Each run. as shown in Figure 9. Figure 14 shows a possible high level description of the heuristic algorithm used for each run-random case (to be verified when source code is available): Begin L = set of LSP’s E = set of all potential links Randomly order LSP’s based on seed iteration = 1 Sequentially route all LSP’s while (iteration < Max_Number_of_Iterations) { for each LSP k { un-route LSP k and release its bandwidth update network state reroute LSP k using min cost routing with new network state } iteration++ } End Figure 14: Heuristic routing algorithm for each random case Lucent Technologies Inc. the lowest cost of which is chosen as the final solution. The run-time is linear with respect to both the number of random cases and the number of iterations. The overall solution is the lowest cost solution of all the runs.Proprietary Use pursuant to Company instructions. The number of random cases refers to the number of different solutions. In each run. the number of iterations specifies multiple solution iterations (discussed below). From the generated order. the LSP’s are sequentially routed using a minimum cost routing algorithm. For each run. network link cost and random seed to be used for a potential subsequent run. of this algorithm starts with a random seed. there are five runs (or random cases). By default. The end result of a run (which could include one or more iterations) is a set of links and LSP routes. Both of these are options.1. Based on [1].2 Number of Iterations and Random Cases The Min_Cost_MPLS_Net_Design feature employs a heuristic based algorithm to arrive at a near optimum topological design. This algorithm used in the Min_Cost_MPLS_Net_Design feature in SPGuru version 11. where link metrics are updated prior to the routing of each LSP. This is called the first iteration. LSP’s are first randomly ordered (using the seed) when there are no links in the network.0 is based on [1]. For each run. with three iterations each.4. These iterations attempt to improve the existing solution. . 13 . or random case. each LSP is un-routed and rerouted one-by-one with all of the other LSP’s still routed. one of the outputs will be a seed chosen for the subsequent run. routers can be overloaded. If enabled. . 14 . The reports contained in this section include supervisory messages.4.3 Other Design Parameters The Max Link Subscription refers to the maximum TE bandwidth assignable to a link as a percentage of its capacity. The first set consists of logs. The capacity conflict would then need to be manually remedied before further design operations on the network. warnings and errors. Figure 15: The design summary log Lucent Technologies Inc. messages and overall design information. The summary log for our design is shown in Figure 15 and includes overall link and cost information. which can be used as a starting point for further design runs. links cannot be placed on routers with exhausted capacity. The second contains detailed information about the added links and LSP routes.Proprietary Use pursuant to Company instructions.5 Output Visualization The Min_Cost_MPLS_Net_Design feature generates two sets of reports. The Best Random Seed refers to the seed for the minimum cost design. The Port Constraint specifies whether or not the maximum number of ports available on an LSR can be exceeded. resulting in a warning message being generated. select Design->Results->Open Log. If disabled.1. design action taken. 1. etc. The Details log (not shown) contains the automatically generated next seed. Most of the fields are self-explanatory. Also note that SPGuru automatically saves the newly designed network in a new scenario. To open the logs. cost and a Details tab that shows information about the contained LSP’s. All links generated are OC-3 links (other candidates were DS3 and OC-12). This information includes source. as shown in Figure 16.Proprietary Use pursuant to Company instructions. . select Design->Results->Open->View Output Tables. destination.To open the output tables. Clicking the Show button at the bottom right corner will spawn a self-contained Links window that contains hyperlinks (shown in red) to link and node objects in the SPGuru GUI. 15 . Figure 16: Design Link Summary Lucent Technologies Inc. Choose Link Summary to access the link report. TE bandwidth. The relevant outputs will be contained under MPLS_MandP_Example_Design. link type. which shows detailed information about the added links. . explicit route name and number of hops. To view the generated links in the SPGuru GUI. hide the LSP’s using Protocols->MPLS->Hide All LSP’s. Figure 18 shows the resulting network topology as viewed through the network browser (View->Show Network Browser). LSP Summary provides access to the LSP report.Similarly.Proprietary Use pursuant to Company instructions. as shown in Figure 17. 16 . Lucent Technologies Inc. In the network browser. TE bandwidth. Selecting a node will drop down the list of links incident to that node. which shows detailed information about the LSP source. the left pane contains the list of nodes. destination. Figure 17: Design LSP Summary All design reports can also be saved as a web report by clicking the Generate Web Report button. and selecting a link will highlight it in the network view. Clicking the show button will spawn a self-contained LSP window that also contains hyperlinks (shown in red) to the SPGuru GUI. 17 . From the GUI. Selecting the explicit routes field will show the LSP route in the network view. In the connections browser. . Lucent Technologies Inc. going through Beijing and Xian. selecting a node on the left pane will drop down the list of LSP’s originating at that node. Selecting the LSP will show the LSP demand in the network view and reveal an explicit routes field. Figure 19 shows the explicit route for an LSP from Chengdu to Guangzhou.Figure 18: Network Browser View of final network topology The LSP explicit routes are stored in the source LSR.Proprietary Use pursuant to Company instructions. one method for viewing the LSP explicit routes is to open the connections browser from Topology->Open Connections Browser. Alberta.Figure 19: Connections Browser view of final network topology References 1. . in Design of Reliable Communication Networks (DRCN) 2003.Proprietary Use pursuant to Company instructions. Chalermpol Charnsripinyo and David Tipper. “Topological Design of Survivable Wireless Access Networks”. Lucent Technologies Inc. Canada. 2003. 18 . Oct. Banff.