Cisco 7600 Series Routers

Enhanced FlexWAN Module Performance and Configuration Guide

White Paper

Cisco 7600 Series Enhanced FlexWAN

Executive Summary

This paper describes in detail internal performance testing of the Enhanced FlexWAN module on the Cisco® 7600 Series Router. Several cases are discussed, including performance results with and without quality of service (QoS) applied, as well as the configurations to achieve that performance. These tests show that the Cisco 7600 Series Enhanced FlexWAN module is a high-performance carrier card capable of 624,000 pps per card.


The Cisco 7600 Series Router is a high-performance edge router that meets the stringent requirements of service provider and enterprise customers. The Cisco 7600 Series delivers optical WAN and metropolitan-area network (MAN) functionality with IP services at the network edge. The Enhanced FlexWAN module extends these scalable WAN and MAN connectivity options to the Cisco 7600 Series and supports most Cisco 7200 and 7500 WAN single-wide port adapters, ranging from fractional T1/E1 to OC-3. The card offers flexible migration options from the Cisco 7500 Series and provides a bridge between existing LAN/WAN/MAN and traditional networks to future high-speed converged voice, video, and data networks.

This paper discusses the performance of the Cisco Enhanced FlexWAN in the following performance characteristics.

  • The switching performance of the Enhanced FlexWAN module without any QoS features applied
  • The switching performance of the Enhanced FlexWAN module with QoS features applied (five Class-Based Weighted Fair Queuing [CBWFQ] classes)
  • The switching performance of the Enhanced FlexWAN module with QoS features applied (CBWFQ and Low-Latency Queuing [LLQ] classes)

Knowledge of the system architecture is necessary to understand the performance data in this paper. The test results are only in reference to the fabric-enabled Cisco 7600 Series Router, which assumes that a Supervisor Engine 2, a switch fabric module (SFM), and all fabric-enabled line cards are installed in the chassis (no classic card presence) or in a Supervisor Engine 720 with an integrated switching fabric. The test results in this paper are identical, regardless of the supervisor engine version.

Test Setup

Equipment used:

  • 2-port packet over SONET (POS) Port Adapter-only one port is used for all of the tests in this paper
  • Enhanced FlexWAN module
  • Ixia Test tool
  • Supervisor Engine 2 with MSFC2 + SFM or Supervisor Engine 720

Figure 1
Test Setup

Performance Test

The test was designed to determine the maximum rate at which packets of various lengths can be forwarded through each bay of the Enhanced FlexWAN module without packet loss. This scenario consists of a series of frames with a particular source and destination IP address for traffic flow. On the receive end, the Ixia only counts frames generated by the sending port as valid frames. If the receiving port receives all frames from the transmitting Ixia ports, no further frames are sent and the maximum frame rate is recorded as the throughput. If a single frame is lost, the frame rate is halved and retried. If all frames are then received, a new frame rate is chosen halfway between the successful and unsuccessful frame rate and retried. This pattern repeats, using a simple binary search until the highest rate at which all frames sent are received can be determined.

Test Results

The test results are detailed in Figures 2-4, and summarized in Figure 5.

Figure 2
Enhanced FlexWAN Module with No QoS Enabled

Figure 3
Enhanced FlexWAN Module with CBWFQ QoS Enabled1

1. QoS configuration used


    class-map match-all class6

      match ip dscp 6

    class-map match-all class7

      match ip dscp 7

    class-map match-all class4

      match ip dscp 4

    class-map match-all class5

      match ip dscp 5

    class-map match-all class2

      match ip dscp 2

    class-map match-all class3

      match ip dscp 3

    class-map match-all class0

      match ip dscp default

    class-map match-all class1

      match ip dscp 1

    class-map match-all any

      match any

    policy-map cbwfq_llq

      class class0

         bandwidth percent 12

      class class1

         bandwidth percent 12

      class class2

         bandwidth percent 12

      class class3

         bandwidth percent 12

      class class4

         bandwidth percent 12

      class class5

         bandwidth percent 12

      class class6

         bandwidth percent 12

      class class7

         priority percent 12

    interface POS8/1/0

      service-policy output cbwfq_llq

Figure 4
Enhanced FlexWAN with CBWFQ/LLQ QoS Enabled

Figure 5
Combined Graphs

With CBWFQ/LLQ enabled and at 128-byte packets, the Enhanced FlexWAN modules achieves the same performance as no QoS. Figures 2-5 show that at 128-byte packets, the lines overlap, highlighting the high-performance switching capabilities with QoS enabled. The total overall performance is equal to 1.25 Mpps per Enhanced FlexWAN module.


The Cisco 7600 Series Enhanced FlexWAN module is a high-performance carrier card capable of upwards of 624,000 pps per card. Because of this performance level, the Enhanced FlexWAN module is able to handle WANs, MANs, and any other network application requiring high performance. When combined with industry-leading features in multicast, routing support, and resiliency, the Cisco 7600 Series provides a superior solution for today's and tomorrow's networks. Proper positioning of a Cisco 7600 Series Router with an Enhanced FlexWAN module can help a company's network infrastructure best support business operations.