Ccct04 Kumar Router
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Throughput Measurements of a Cisco-2600 Router Hugo E. Roble s, Student Member, IEEE and Sanjee v Kumar, Senior Member, IEEE Networking Research Lab, Department of Electrical Engineering, The University of Texas-Pan American, Edinburg, TX -78541, USA Ph: 956-381-2401, Email: [email protected] Abstract Cisco 2600 series routers are popularly deployed as edge routers. In this paper, we present results of our tests conducted to measure the performance of a Cisco- 2651XM router. The benchmarking methodology for network-interconnect devices as prescribed in RFC-2544 was used to measure router’s throughput. It is observed that even though the router supports 100baseT interfaces each with line-speed of 100 Mbps, the router can only support an aggregate throughput of around 30 Mbps for largest-size frames and an aggregate throughput of around 20 Mbps for small est- size frames with zero loss-tolerance. 1. Introduction Cisco routers such as the class of 2600 series routers are quite popular as edge routers. In this paper we present measurement results that we conducted in a lab environment to evaluate throughput performance of a Cisco 2600 series routers. In our lab experiments, a Cisco 2651XM router [1] was tested to determine its throughput performance. The tests performed were those described in RFC 2544, which is entitled Benchmarking Methodology for Network Interconnect Devices [2]. 2. Experiment Setup As required by the document [2], the experiment was setup as illustrated in Fig.1. The Device Under Testing (DUT) was the Cisco-2651XM router and the tester was a hardware traffic generator and performance analyzer capable of testing Layer 2 and 3 devices. The tester utilized two of its ports to connect to the two Fast-Ethernet interfaces (100 Mbps) of the router. One port was designated to transmit and the other to receive frames, also referred to as one-to-one traffic mapping. Fig. 1: Experimental Hardware Setup The traffic generator is equipped with 4 Fast-Ethernet ports. These ports can simultaneously transmit and receive traffic at the maximum rate of 100 Mbps. The user can specify the transmit rate anywhere from 1% to 100% of its theoretical maximum capacity, which is 100 Mbps. In receive mode, the user can specify the loss tolerance permitted within a test. For example, if the loss tolerance is set to 0% then it means none of the transmitted frames should be dropped by the router, and the test system should be able to recuperate all the frames it transmitted for a given load. On the other hand, if the loss tolerance is set of some non-zero value then it means that the test allows some flexibility in frame-loss incurred by the router. During evaluation, the router was not connected to anything other than the tester. It had the minimal configuration required to allow routing to occur. OSPF was used as the preferred routing protocol. No security access lists were implemented.
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Transcript of Ccct04 Kumar Router
8/8/2019 Ccct04 Kumar Router
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Throughput Measurements of a Cisco-2600 Router
Hugo E. Robles, Student Member, IEEE
and
Sanjeev Kumar, Senior Member, IEEENetworking Research Lab, Department of Electrical Engineering,
The University of Texas-Pan American, Edinburg, TX-78541, USAPh: 956-381-2401, Email: [email protected]
Abstract
Cisco 2600 series routers are popularly deployed as edgerouters. In this paper, we present results of our tests
conducted to measure the performance of a Cisco-2651XM router. The benchmarking methodology fornetwork-interconnect devices as prescribed in RFC-2544was used to measure router’s throughput. It is observedthat even though the router supports 100baseT interfaceseach with line-speed of 100 Mbps, the router can onlysupport an aggregate throughput of around 30 Mbps forlargest-size frames and an aggregate throughput of around20 Mbps for smallest-size frames with zero loss-tolerance.
1. Introduction
Cisco routers such as the class of 2600 series routers arequite popular as edge routers. In this paper we presentmeasurement results that we conducted in a labenvironment to evaluate throughput performance of aCisco 2600 series routers. In our lab experiments, a Cisco2651XM router [1] was tested to determine its throughputperformance. The tests performed were those described inRFC 2544, which is entitled Benchmarking Methodologyfor Network Interconnect Devices [2].
2. Experiment Setup
As required by the document [2], the experiment wassetup as illustrated in Fig.1.
The Device Under Testing (DUT) was the Cisco-2651XMrouter and the tester was a hardware traffic generator andperformance analyzer capable of testing Layer 2 and 3devices. The tester utilized two of its ports to connect tothe two Fast-Ethernet interfaces (100 Mbps) of the router.One port was designated to transmit and the other to
receive frames, also referred to as one-to-one trafficmapping.
Fig. 1: Experimental Hardware Setup
The traffic generator is equipped with 4 Fast-Ethernetports. These ports can simultaneously transmit andreceive traffic at the maximum rate of 100 Mbps. Theuser can specify the transmit rate anywhere from 1% to100% of its theoretical maximum capacity, which is 100Mbps. In receive mode, the user can specify the losstolerance permitted within a test. For example, if the losstolerance is set to 0% then it means none of thetransmitted frames should be dropped by the router, andthe test system should be able to recuperate all the framesit transmitted for a given load. On the other hand, if theloss tolerance is set of some non-zero value then it meansthat the test allows some flexibility in frame-loss incurredby the router.
During evaluation, the router was not connected toanything other than the tester. It had the minimalconfiguration required to allow routing to occur. OSPFwas used as the preferred routing protocol. No securityaccess lists were implemented.
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For throughput evaluation, different sizes of the Ethernetframes were used. RFC 2544 specifies that the Ethernetframes should be used of sizes 64, 128, 256, 512, 1024,1280, 1518 bytes. These sizes include the minimum andmaximum frame sizes, 64 and 1518 bytes respectively,allowed by the IEEE 802.3 Ethernet standard [4].
3. Router Throughput according to RFC 1242Definitions
The router throughput according to RFC 1242 [3] isdefined as the maximum rate at which none of the offeredframes are dropped by the device. That is equivalent torouter’s forwarding rate with zero loss-tolerance.
Although many applications tolerate some frame loss, thedefinition of throughput is such that it guarantees that noframes are lost at the device’s maximum allowed rate.However, for non-zero loss-tolerance, a linear increase inthroughput is expected before reaching a plateau as theloss-tolerance is increased.
4. Throughput Test Results
The throughput test performed on the Cisco 2651XMrouter determines the maximum rate at which frames canbe forwarded by the router for a given frame losstolerance. The tester initially transmits at full capacity(100 Mbps) and checks if the router is capable of forwarding the frames while maintaining the specifiedframe loss tolerance. If not, it decreases its transmission
rate until the frame loss specification is satisfied on thereceiving end of the tester. The tester uses a binary searchalgorithm [5] to determine the router throughput rate. Theresults are shown below for zero and fifty percent losstolerance in Fig.2, and Fig.3 respectively.
Fig. 2: Cisco-2651XM Router Throughput with 0%Forwarding Frame Loss and its corresponding Kpps
performance
Fig. 3: Cisco 2651-XM Router Throughput with 50%Forwarding Frame Loss Tolerance and its corresponding
Kpps performance.
The Fig. 2 shows the maximum forwarding throughputthat the router can handle for a given frame size at zeropercent frame loss. The kilo-packets-per-second (kpps)histogram adds a new perspective to the data. Fromthroughput forwarding alone, it seems that throughputincreases as frame size becomes larger. However, thisrelation is inversely proportional to the amount of Kppsthat the router can forward, that is, the larger the framesize, the lower the quantity of packets that are forwarded.
Even though this 2600-series router supports FastEthernet Interface (=100Mbps), the maximum throughputperformance with zero loss-tolerance of the router is
found to be only around 30%, especially when the largestpossible frame size (=1518 bytes) is used. The router hasfast Ethernet interface with maximum speed of 100 Mbps,however, the effective throughput rate of this router ismeasured to be only 30 Mbps. This translates toforwarding rate of 2.5 Kpps. The smallest possible framesize (=64 bytes) has adverse effect on the routerthroughput and under such conditions as shown in Fig.2,only 20% of the throughput is achievable. Under thiscondition, this router with fast Ethernet interface can onlyhandle a data stream of ~12.5 Mbps (without droppingany frame) and this translates to forwarding rate of 25Kpps.
The histogram in Fig.3 justifies Cisco Systems claim [6]that the 2651XM router can handle up to 40 Kpps.However, it is observed that the 40 Kpps forwarding bythe 2651XM router is achieved at 50% frame-losstolerance. At 50% loss-tolerance, it is observed that for 64bytes frames, the throughput achieved was ~ 21 Mbps.
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5. Conclusion
In this paper, we present performance measurementresults for a Cisco-2600 series edge-router. Thebenchmarking methodology for network-interconnectdevices as prescribed in RFC-2544 was used to measurethe router’s throughput performance. It is observed thateven though the router supports 100baseT interfaces eachwith line-speed of 100 Mbps, the router can only supportwith 0% loss-tolerance, an aggregate throughput of around 30 Mbps for largest-size frames and an aggregatethroughput of around 12 Mbps for smallest-size frames.Furthermore, it is observed that Cisco’s claim of 40 Kppsforwarding capacity for the 2651XM routers can only beachieved at the cost of 50% frame-loss tolerance. Themaximum forwarding rate that can be achieved with 0%loss-tolerance is measured to be only around 25 Kppswith smallest possible frame size of 64 bytes.
References
[1]http://www.cisco.com/en/US/products/hw/routers/ps259/ps4834/index.html
[2] http://www.ietf.org/rfc/rfc2544.txt
[3] http://www.ietf.org/rfc/rfc1242.txt
[4]http://standards.ieee.org/getieee802/download/802.3-
2002.pdf
[5] http://www.compute101.com/binary_search.htm
[6]http://www.cisco.com/en/US/products/hw/routers/ps259/products_data_sheet09186a00801761b1.html
