Download Network-Wide Class of Service (CoS) Management

Network-Wide Class of
Service (CoS) Management
with Route Analytics
Integrated Traffic and Routing
Visibility for Effective CoS Delivery
CoS Management
Executive Summary
Enterprise IT and service providers alike are under pressure to deliver on service-level
expectations that have been raised for critical applications by the deployment of different
Classes of Service (CoS) in their networks. Unfortunately, due to technological constraints
inherent in today’s network management approaches, network managers lack the networkwide CoS traffic visibility needed to engineer, operate and plan the network to deliver on
those expectations.
Today that lack of visibility need no longer be a given. Route analytics technology
combined with a small footprint of collected NetFlow data can provide CoS traffic visibility
not only to every link in the network, but to the network-wide context of each link’s traffic,
enabling network managers to get a handle on CoS delivery.
The Scalability and Intelligence Limitations of Interface-Centric CoS
Traffic Analysis
Assigning CoS priorities is a way to ensure proper delivery of sensitive traffic in the
essentially unpredictable world of IP networks. The issue with CoS delivery is that, IP's
major advantage—its distributed routing intelligence—means that traffic paths can shift
dynamically across various links in the network based on link conditions and network
configuration changes. When shifts occur, CoS traffic can exceed thresholds, causing
priority packets to be dropped or delayed, negatively impacting sensitive applications and
services. As a result, network engineers need to be able to monitor every link’s CoS traffic
and to understand exactly how (from a routing point of view) traffic is being delivered
across the network. Armed with this knowledge, engineers can catch emerging congestion
issues and respond based on an understanding of the network’s operational architecture.
Until now, this sort of visibility has existed only in network engineers’ dreams. Traffic
analysis has been performed either by embedding probes to collect and analyze interface
data, or by enabling flow-recording techniques such as NetFlow on router and switch
interfaces. While both techniques have greatly increased the knowledge of end-to-end IP
traffic-flow delivery compared to simple device counters provided by SNMP polling, they
suffer from a major limitation held in common with SNMP: their interface-centric approach.
When probes are embedded in a network, they must be deployed against a particular
interface’s traffic. Likewise, NetFlow is turned on per interface. The huge networks run by
enterprises and service providers can have tens of thousands of such interfaces. And
while it is theoretically possible to instrument every single interface on the network with
NetFlow, the traffic overhead can make this impractical, while trying to deploy such high
numbers of hardware probes is so expensive that it simply is not done.
The reality is that large networks tend to gather flow information only at so-called “key
points”—major WAN links, data centers, Internet peerings and major customer interfaces.
Furthermore, even with NetFlow collected from many points in the network, looking at
traffic from the point of view of one interface after another often reveals data at too raw a
level to
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CoS Management
help network managers deal with an emergent network condition or plan for growth. The
current state of CoS traffic management is that the vast majority of network managers
responsible for large, complex and redundant IP networks have little or no insight into the
state and root-cause issues of CoS delivery in their large core network domains, and no
idea at all how their IP network’s routing affects traffic delivery. With recent technology
developments, this is no longer an acceptable – or necessary – state of affairs.
Route Analytics—A Game-Changing Technology for CoS Traffic
Analysis
A technology called route analytics that has been adopted by hundreds of large enterprises,
government agencies and service providers is changing network managers’ fundamental
assumptions about the level of visibility they can have into network-wide CoS traffic
delivery. Route analytics is built on the foundation of a different type of network visibility,
afforded by tapping into the routing protocols – the source of intelligence that determines
how IP networks deliver traffic.
Route analytics is the technique of acting like a router and peering with select routers
across a network using routing protocols—OSPF, IS-IS, EIGRP and BGP—to record the
routing control messages that routers use to calculate how traffic will be sent across the
network. By taking this information and processing it just the way routers do – albeit in a
more comprehensive fashion – route analytics creates an analyzable routing topology of the
entire network that exactly reflects the way the real network is operating. As a result, route
analytics understands every routed path from every host in the network to every other host.
Since it records every routing protocol message, route analytics also keeps a complete,
replayable history of changes in that routing topology and can be used to accurately
simulate the effects of changes to that topology.
Engineers find this sort of routing topology information very useful on its own for
troubleshooting and network planning. But the implications of route analytics on networkwide CoS traffic analysis extend far beyond these tasks, because of the way the vast
majority of traffic is disseminated across the network: From a relatively few major ingress
points in major data centers, Internet and network and customer peering points, which
constitute a tiny fraction of the networks’ total number of interfaces. By collecting NetFlow
data from these points and then using knowledge of the precise route that every flow takes
at any time through the network, route analytics can create a highly accurate, integrated
routing and traffic map that shows the volume of CoS traffic on every link in the network.
Furthermore, since route analytics understands how every flow gets to every link, it provides
the network-wide context for every interface’s traffic. For the first time, network engineers
can see the big picture – the network as a holistic, dynamic organism – and immediately
grasp the impact of routing changes or failures on traffic (even traffic located many hops
away from where a change has occurred). Route analytics provides a number of beneficial
capabilities for CoS management:
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CoS Management
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CoS monitoring visibility for all links: Route analytics allows network managers to
monitor traffic by specific class of service on every network link. Alerts can be sent
when service classes go out of profile.
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CoS traffic problem localization and root-cause analysis: Since network managers
know how service traffic gets to a particular link, it's much easier to discern whether
out-of-profile CoS conditions are due to routing changes that shift traffic to or from a
link, or to new traffic coming into the network at the time the problem occurred.
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Replayable routing and CoS traffic history. One of the chief problems in
troubleshooting application issues is that when the network is suspect, there is often
no history to examine to prove or disprove that suspicion or localize the problem
domain within the network. Route analytics continuously records routing and traffic
so that network engineers can literally “rewind the network” to look at and even
replay past event streams (see Figure 1). This high-fidelity forensic history greatly
decreases mean time to repair (MTTR).
Figure 1: Route analytics’ continuously recorded database of all routing and traffic changes
can be rewound to look at a particular timeframe when a problem was occurring, providing
an unprecedented forensic and troubleshooting history for network engineers.
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CoS Management
Once an engineer has selected a timeframe, the precise routed path of the application
traffic can be examined for routing instabilities such as link or prefix flapping, and for outof-profile CoS conditions, as seen in Figure 2.
Figure 2: Engineers can select any two endpoint IP addresses and highlight the exact
routed path taken by the application traffic in question at the time a problem was occurring
in order to narrow down the part of the network that needs to be analyzed.
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Modeling the impact of network changes and maintenance: Network engineers
planning network changes or even performing routine maintenance can simulate
various changes to ensure that CoS traffic will stay in profile based on those changes.
Since the modeling is done on the actual state of routing and traffic, engineers can
have a high degree of confidence in their planning and maintenance operations. For
example, before making changes in the network, engineers can simulate those
changes in the route analytics network model, then ensure via simulated metric
changes that the network will behave as intended after the change is deployed, as
shown in Figure 3:
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CoS Management
Figure 3: Route analytics can be used to simulate a variety of network changes, such as
adding, downing, and moving routers, links and peerings, as well as tuning of routing
metrics.
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Failure analysis and routing audits for service assurance: Route analytics also allows
for simulation of failures on key links and components to let network managers
analyze their impact on CoS traffic in the network. In addition, network engineers
can run a comprehensive routing audit of the network to reveal suboptimal routing
for delay-sensitive traffic such as Equal Cost Multi Paths (ECMPs), asymmetric paths,
and links where failures could cause large variations in path lengths, as shown in
Figure 4.
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CoS Management
Figure 4: Comprehensive path reports allow network engineers to examine the health of
their routing operations for potential trouble or vulnerability, such as where there is only a
single path to important destinations.
The Link Between Application Delivery and the Network
Infrastructure
Simply assigning CoS priorities to critical traffic types such as VoIP or SAP is no guarantee
that those priorities will be enforced in complex, redundant IP networks. And when
priorities aren't observed, network managers in enterprises are on the line for reduced
productivity, and in service provider organizations for failure to meet SLAs. Conventional
link- and device-oriented management tools alone can't provide the visibility needed to
detect anomalies caused by dynamic IP routing – e.g., misconfigured routers, high volumes
of new customer traffic – that can easily disrupt traffic even when they don't cause any
specific link or device to fail. Route analytics technology provides network-wide visibility
into traffic flows and related routing dynamics that dramatically increase network
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CoS Management
management visibility into CoS traffic delivery. Complementing other network management
solutions, such as application performance management and SNMP device management
and fault correlation systems, route analytics provides the Layer 3 network delivery link
between end-to-end application performance and the underlying network infrastructure
elements.
For more information on route analytics technology and solutions, please:
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Email us at [email protected]
Visit Packet Design’s web site at http://www.packetdesign.com
Call us at 408.490.1000
Corporate Headquarters
Packet Design Inc.
2455 Augustine Drive
Santa Clara, CA 95054
Phone: 408.490.1000
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http://www.packetdesign.com
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