network-wide traffic capacity planning with route analytics · network-wide capacity planning 2008...

Network-Wide Capacity Planning

with Route Analytics

White Paper


2008 Packet Design, Inc. of 17

Executive Summary Capacity planning is an important business process in large IP networks for ensuring reliable application and service delivery. In the days of fixed circuits and few applications, while not trivial, capacity planning was at least based on predictable bandwidth utilization characteristics. However, the complex and dynamic nature of IP networks with their self-healing routing algorithms, virtual private networks, varying Classes of Service (CoS) and convergence of both best effort and highly sensitive traffic, make capacity planning both more critical and difficult. Unfortunately, many organizations struggle to perform effective capacity planning due to relatively shallow statistical data that doesn’t support the deep analyses needed to ensure that capacity plans are both technically and financially sound. Fortunately, a solution exists to bring much deeper insight to IP network and service capacity planning. Route analytics technology—the use of the network’s live routing protocol data as the foundation for understanding the network’s actual traffic behavior—can be leveraged for unprecedented network-wide routing and traffic visibility, including network-wide IP traffic capacity planning and modeling Route analytics provides an operationally accurate level of planning visibility, including rich details of the composition of the traffic, a continuously recorded traffic history across the entire network. This broad and deep insight provides the basis for easy to use capacity planning and trending tools. In addition, the algorithmically accurate nature of route analytics understanding of network routing and traffic means that it can also provide powerful scenario modeling to anticipate the impact of specific planned changes in the network... This white paper reviews the limitations to traditional capacity planning approaches, explains how route analytics works, and demonstrates the advantages that network planners can gain by utilizing route analytics’ capacity planning and modeling capabilities.

The Limits of Traditional Capacity planning Traditional capacity planning, like most of today’s network management technology, is based on collection of interface-specific utilization information via SNMP, typically at an aggregate level. By collecting interface utilization statistics snapshots over time, engineers can use manual means, scripts, or capacity planning tools to project utilization trends and understand when particular interfaces will reach certain capacity limits. This is certainly useful information, but it isn’t enough. Sound planning processes and financial budget justifications not only demand an understanding of how much utilization is increasing, but also whywhywhywhy utilization is rising on particular interfaces, whether there are any alternatives to purchasing upgrades, and if the planned changes will truly meet the projected need. Unfortunately, the limited statistical information available to network planners and the nature of most capacity planning tools don’t provide the analyses needed to answer these questions. In some cases, anecdotal knowledge of certain end user or customer situations or occurrences may allow network planners to create upgrade justifications, but without greater visibility, planning processes can suffer inaccuracies that lead to either underplanned capacity that impacts application and service delivery, or overspending that impacts the business bottom-line and makes it harder to justify future capital expenses.



Route Analytics—Network-Wide Traffic Visibility Route analytics technology provides the breadth and depth of capacity planning analysis needed to ensure that the network is able to meet its application and service delivery mission, while optimizing or limiting capital costs. Route analytics is a technology that leverages the intelligence in routing protocols to automatically build and maintain an always-accurate routing map of any IP network, across AS, areas, multiple protocols, and even MPLS VPNs. Route analytics solutions peer with key routers in each AS or area, passively listening to and recording every routing update communicated throughout the network, then using the same algorithms that run on routers to calculate and deliver a routing topology map as accurate as the network’s actual routers understand it. Based on this routing map, route analytics then intelligently integrates Netflow data collected from a small subset of network interfaces to create an integrated, dynamically updated routing and traffic map. This integrated view is distinct from traditional methods of Netflow analysis, which do no more than present link-by-link flow data in separate tabular reports. Route analytics collects Netflow records from routers handling the majority of traffic flows into a network, such as at data centers, Internet peerings and key WAN links. It then utilizes its always accurate knowledge of routing paths to map each traffic flow across the precise links it traverses in the actual network. The result is a network-wide map of all links with accurate real-time and historical traffic utilization that can be analyzed by CoS, VPN customer, BGP attributes, custom traffic classes, and granular traffic flow details. This map can be “rewound” to past moments in time to perform forensic analysis on the exact state of traffic and routing at that time, greatly speeding troubleshooting processes. It can also perform modeling simulations of routing and traffic changes, showing exactly how the whole network would behave in response and strengthening change management processes. Route analytics intelligence can also support comprehensive and detailed capacity planning that helps deliver high quality network service while optimizing capital expenses.

Capacity Planning with Route Analytics Since route analytics continuously records the changing state of routing and traffic across the entire network, it has a built-in historical record from which to project traffic trends. Engineers can easily generate capacity planning projections for every link in the network either to a date or to a capacity limit, as see in Figure 1 and 2



Figure 1: Route analytics can easily produce trending reports on all links in the network

Figure 2: Trending results on all links in the network



Route analytics also provides rich analytical details so that engineers can examine the mix of traffic in the network by a variety of criteria and views, such as by customer, CoS, ingress and egress routers, as seen in figures 3 through 5.

Figure 3: Traffic by customer

Figure 4: Traffic by CoS per link



Figure 5: Traffic by Egress (PE) router for a particular customer and link To understand why a particular traffic trend is occurring, Engineers can find out more information about the trend of a particular aspect of traffic, they can examine the history of any particular link, customer, Class of Service, or other traffic classification, as seen in Figure 3.

Figure 6: Traffic history can be viewed on a per-link, CoS, VPN or other basis to gain greater planning intelligence. Specific trending reports can be generated for any particular drill-down traffic report, as seen in figure 7:



Figure 7: Traffic trending for one link. Trending reports can be generated for any subset of traffic

Change Modeling to Validate the Effects of Planned Upgrades and Explore Alternative Solutions Not only can route analytics project trends and provide the detailed analysis needed to understand the need for capacity upgrades, but it also allows planners to perform modeling simulations of network capacity upgrades and other proposed network changes, then view exactly how the entire network’s behavior would respond. Since the modeling is performed not on an abstract version of the network, but on its actual routing and traffic, it is highly accurate. Route analytics modeling capability ensures that capacity upgrades are wisely planned and will be effective, and also allows network engineers to explore other, less costly means of meeting utilization level objectives, perhaps by moving servers between data centers, or by changing routing metrics to shift traffic from links that are projected to become congested to underutilized ones. For example, a multi-national Fortune 500 enterprise wanted to know what would happen to link utilization on core WAN circuits if servers were moved to a different data center. For the sake of scope, a particularly important circuit was chosen for focused analysis, as shown in Figure 8.



Figure 8: Route analytics helps engineers understand how WAN circuits would behave after a data center migration. Since route analytics records and stores a complete forensic history of all routing and traffic changes, network managers were able to "rewind” to a point in time where there was a historically high level of WAN circuit utilization, and use this as the basis for the planning and simulation exercise. A histogram of traffic utilization across any selected link or any portion of the network in aggregate is seen in Figure 9.

What happens to link utilization of core WAN circuits if servers are moved

from this location to this location?

Route analytics can show the effect on all circuits, but this circuit

will be used to illustrate in detail



Figure 9: Network managers found a past point of high utilization to use as the basis for their data center migration simulation exercise. Clicking on any link in the network map reveals rich details on routing and traffic state at that moment in time. In this case, network managers were able to see the precise utilization of the WAN link in question, in both directions, as seen in Figure 10.

Route analytics lets users view the state of routing and traffic at any point in the recorded

database

In this case, the network manager moves back in time to

a period of high utilization (to see worst case-scenario)



Figure 10: Route analytics’ network map provides rich details on routing and traffic for links, paths, and routers, such as WAN link utilization. Having selected a particular point in time, the network manager can simulate routing and traffic changes based on the state of the network at the time being viewed. The network manager selects the router in the data center that delivers the traffic from the servers that are to be moved, and displays a list of network addresses (or prefixes). Then he simulates the downing of the prefix representing the server cluster, as seen in Figure 11.

At the selected time period:

Southbound traffic on this link is 37.72Mbps (it is experiencing high utilization, so

half the link is red)

Northbound traffic utilization is negligible, so the

northbound half is grey (indicating low utilization)



Figure 11: Route analytics allows network managers to view comprehensive information such as a list of all routed prefixes, which eases network change simulations such as downing a prefix. Next, the network manager opens the router in the data center to which the servers are being moved, and adds the downed prefix from the first data center to simulate the server cluster being brought up in that data center, as seen in Figure 12. Route analytics simulates the re-routing of all traffic destined for this prefix to the new network location. This simulation is completely accurate, since it is based on the precise state of routing and traffic at that moment in time.

For the data center router, the network manager displays the

list of networks (prefixes) it supports....

then simulates downing the prefix to be moved



Figure 12: Moving the server cluster is modeled by adding the previously downed prefix from the first data center to a router handling traffic at the new data center. Route analytics now displays a network map, as seen in Figure 13, which shows that utilization in the southbound direction on the WAN link has decreased slightly, while the northbound utilization has changed from negligible to high. This is important intelligence for the network engineering team, which can now perform further analyses to find a way to accommodate the proposed change without incurring new costs.

Traffic Explorer can simulate moving servers from the

first data center to the second one by moving the prefixes,

thus re-routing traffic to the new datacenter.



Figure 13: Route analytics shows precisely how the network would behave after a planned change. In this case, northbound link utilization for the WAN circuit in question would be too high, so further planning adjustments will be needed before this change is implemented. For the specific WAN link examined in this case, an unacceptable utilization level would occur as a result of this data center move, prompting the network managers to further analyze their options. Route analytics provides comprehensive link utilization analysis capabilities to ease analysis of the before-and-after effects of specific change scenarios.

After the modeled change:

Southbound traffic on this link has DECREASED to 37.67Mbps from 37.72Mbps

(it is still high utilization, so

half the link is red).

#2 For Northbound traffic, utilization is

HIGH, so the Northbound half is RED.



Figure 14: Route analytics provides comprehensive link utilization information on a before-and-after simulated change basis.

Network managers can examine how ALL of

the links in the ENTIRE network have been affected

by this move via Link Utilization,

Link Traffic and Available Capacity

Reports.



Figure 15: Route analytics provides insight into network-wide available capacity for real-time monitoring as well as for historical analysis and modeling purposes. Using this intelligence and further network change modeling and simulation, the network managers may be able to find a way to adjust routing to accommodate the traffic without incurring additional WAN circuit costs (e.g., by modifying certain router metrics). Upon performing these simulations, they may further find, by looking at link traffic analyses and finding links with low utilization, that certain WAN links can be decommissioned or cost-reduced (see Figure 16).

We can see available capacity across the

ENTIRE network after simulating the

data center move.



Figure 16: Network managers can find ways to optimize use of existing network assets to contain or reduce costs by modeling changes and finding under-utilized or unutilized links.

Benefits of Route Analytics to Capacity Planning Processes Route analytics provides a number of benefits for capacity planning departments and processes:

• Automates the collection of bottoms-up accurate data on the behavior of routing and traffic over time

• Provides easy to use capacity planning tools that leverage already stored network history

• Offers rich analytical details on the composition of projected traffic, and why certain trends are occurring

• Supports modeling of planned routing and traffic changes, allowing network planners to validate that their planned capacity changes will have the effect desired, and also creating options to utilize existing, underutilized network assets to save money

• Increases the accuracy and efficiency of capacity planning processes, decreases capital expenditures, and provides the basis for clear and detailed business justification of needed capacity upgrades

This circuit bandwidth can now be

reduced to save cost!



Conclusion As pressure increases on network managers to deliver predictable application availability and performance, especially with the advent of more sensitive converged services such as VoIP, they need the automation, accuracy, depth of analysis, and modeling capabilities of route analytics to ensure that their planning processes drive sound business and technology decisions. Route analytics provides network planners with unique visibility to optimize, validate and justify their plans and deliver a better overall value to the business. With network-wide visibility of routing and traffic behavior, network planners can deliver higher service levels while maximizing IT assets. To learn more about Packet Design and its industry-leading route analytics solutions, please:

• Email us at [email protected]

• Visit Packet Design’s web site at http://www.packetdesign.com

• Call us at 650.739.1850

Corporate Headquarters Packet Design Inc.

3400 Hillview Avenue, Building 3

Palo Alto, CA 94304 Phone: 650.739.1850

Fax: 650.739.0590

http://www.packetdesign.com

network-wide traffic capacity planning with route analytics · network-wide capacity planning 2008...

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