Benchmarking Working Group                               Brooks Hickman
Internet-Draft                                   Spirent Communications
Expiration Date: April June 2003                                 David Newman
                                                           Network Test
                                                        Saldju Tadjudin
                                                 Spirent Communications
                                                           Terry Martin
                                                    GVNW Consulting Inc
                                                           October 2002
                                                           January 2003

          Benchmarking Methodology for Firewall Performance
              <draft-ietf-bmwg-firewall-07.txt>
              <draft-ietf-bmwg-firewall-08.txt>

Status of this Memo

  This document is an Internet-Draft and is in full conformance with
  all provisions of Section 10 of RFC2026.

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Copyright Notice

  Copyright (C) The Internet Society (2002). All Rights Reserved.

Abstract

   This document discusses and defines a number of tests that may be

   used to describe the performance characteristics of firewalls. In
   addition to defining the tests, this document also describes
   specific formats for reporting the results of the tests.

   This document is a product of the Benchmarking Methodology Working
   Group (BMWG) of the Internet Engineering Task Force (IETF).

Table of Contents

   1. Introduction . . . . . . . . . . . . . . . . . . . . . . . .  2
   2. Requirements . . . . . . . . . . . . . . . . . . . . . . . .  2
   3. Scope  . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   4. Test setup . . . . . . . . . . . . . . . . . . . . . . . . .  3
   4.1 Test Considerations   . . . . . . . . . . . . . . . . . . .  4
     4.2 Virtual Client/Servers  . . . . . . . . . . . . . . . . .  4
     4.3 Test Traffic Requirements . . . . . . . . . . . . . . . .  4
     4.4 DUT/SUT Traffic Flows . . . . . . . . . . . . . . . . . .  5
     4.5 Multiple Client/Server Testing  . . . . . . . . . . . . .  5
     4.6 NAT(Network Network Address Translation) Translation (NAT) . . . . . . . . . . . .  5
     4.7 Rule Sets . . . . . . . . . . . . . . . . . . . . . . . .  5
     4.8 Web Caching . . . . . . . . . . . . . . . . . . . . . . .  6
     4.9 Authentication  . . . . . . . . . . . . . . . . . . . . .  6
     4.10 TCP Stack Considerations . . . . . . . . . . . . . . . .  6
   5. Benchmarking Tests . . . . . . . . . . . . . . . . . . . . .  6
     5.1 IP throughput . . . . . . . . . . . . . . . . . . . . . .  6
     5.2 Concurrent TCP Connection Capacity  . . . . . . . . . . .  8
     5.3 Maximum TCP Connection Establishment Rate . . . . . . . . 10
     5.4 Maximum TCP Connection Tear Down Rate . . . . . . . . . . 12
     5.5 Denial Of Service Handling  . . . . . . . . . . . . . . . 14
     5.6 HTTP Transfer Rate  . . . . . . . . . . . . . . . . . . . 15
     5.7 Maximum HTTP Transaction Rate . . . . . . . . . . . . . . 18
     5.8 Illegal Traffic Handling  . . . . . . . . . . . . . . . . 20
     5.9 IP Fragmentation Handling . . . . . . . . . . . . . . . . 21
     5.10 Latency  . . . . . . . . . . . . . . . . . . . . . . . . 23
   6. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
   7. Security Consideration . . . . . . . . . . . . . . . . . . . 26
   8. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . 26
   9. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 27
   Appendix A - HyperText Transfer Protocol(HTTP) Protocol (HTTP) . . . . . . . . 28
   Appendix B - Connection Establishment Time Measurements . . . . 28
   Appendix C - Connection Tear Down Time Measurements . . . . . . 29
   Full Copy Copyright Statement  . . . . . . . . . . . . . . . . . . . . . . 30

1. Introduction

   This document provides methodologies for the performance
   benchmarking of firewalls. It provides methodologies in covers four areas: forwarding,
   connection, latency and filtering. In addition to
   defining the tests, this document also describes specific formats
   for reporting the results of the tests. test results.

   A previous document, "Benchmarking Terminology for Firewall
   Performance" [1], defines many of the terms that are used in this
   document. The terminology document SHOULD be consulted before
   attempting to make use of this document.

2. Requirements

   In this document, the words that are used to define the significance
   of each particular requirement are capitalized.  These words are:

   *  "MUST" This word, or the words "REQUIRED" and "SHALL" mean that
      the item is an absolute requirement of the specification.

   *  "SHOULD" This word or the adjective "RECOMMENDED" means that
      there may exist valid reasons in particular circumstances to
      ignore this item, but the full implications should be understood
      and the case carefully weighed before choosing a different
      course.

   *  "MAY" This word or the adjective "OPTIONAL" means that this item
      is truly optional.  One vendor may choose to include the item
      because a particular marketplace requires it or because it
      enhances the product, for example; another vendor may omit the
      same item.

   An implementation is not compliant if it fails to satisfy one or more
   of the MUST requirements.  An implementation that satisfies all the
   MUST and all the SHOULD requirements is said to be "unconditionally
   compliant"; one that satisfies all the MUST requirements but not all
   the SHOULD requirements is said to be "conditionally compliant".

3. Scope

   Firewalls can provide a single point of defense control access between networks. Usually, a firewall
   protects a private networks from the public or shared networks network(s) to
   which it is connected. A firewall can be as simple as a single
   device that filters different packets or as complex as a group of devices that
   combine packet filtering and application-level proxy or and network
   translation services. This RFC
   will focus document focuses on developing benchmark testing of DUT/SUTs, benchmarking firewall
   performance - wherever possible, independent of their implementation.

4. Test Setup

   Test configurations defined in this document will be confined to
   dual-homed and tri-homed as shown in figure 1 and figure 2
   respectively.

   Firewalls employing dual-homed configurations connect two networks.
   One interface of the firewall is attached to the unprotected
   network[1], typically the public network(Internet). The other
   interface is connected to the protected network[1], typically the
   internal LAN.

   In the case of dual-homed configurations, servers which are made
   accessible to the public(Unprotected) network are attached to the
   private(Protected) network.

      +----------+                                       +----------+
      |          |    |       +----------+        |      |          |
      | Servers/ |----|       |          |        |------| Servers/ |
      | Clients  |    |       |          |        |      | Clients  |
      |          |    |-------|  DUT/SUT |--------|      |          |
      +----------+    |       |          |        |      +----------+
           Protected  |       +----------+        | Unprotected
            Network   |                           |   Network
                          Figure 1(Dual-Homed) 1 (Dual-Homed)
   Tri-homed[1] configurations employ a third segment called a
   Demilitarized Zone(DMZ). With tri-homed configurations, servers
   accessible to the public network are attached to the DMZ. Tri-Homed
   configurations offer additional security by separating server(s)
   accessible to the public network from internal hosts.

      +----------+                                       +----------+
      |          |    |       +----------+        |      |          |
      | Clients  |----|       |          |        |------| Servers/ |
      |          |    |       |          |        |      | Clients  |
      +----------+    |-------|  DUT/SUT |--------|      |          |
                      |       |          |        |      +----------+
                      |       +----------+        |
            Protected |            |              | Unprotected
             Network               |                   Network
                                   |
                             -----------------
                                       |    DMZ
                                       |
                                       |
                                +-----------+
                                |           |
                                | Servers   |
                                |           |
                                +-----------+

                             Figure 2(Tri-Homed) 2 (Tri-Homed)

4.1 Test Considerations

4.2 Virtual Clients/Servers

   Since firewall testing may involve data sources which emulate
   multiple users or hosts, the methodology uses the terms virtual
   clients/servers. For these firewall tests, virtual clients/servers
   specify application layer entities which may not be associated with
   a unique physical interface. For example, four virtual clients may
   originate from the same data source[1]. The test report MUST
   indicate the number of virtual clients and virtual servers
   participating in the test.

4.3 Test Traffic Requirements

   While the function of a firewall is to enforce access control
   policies, the criteria by which those policies are defined vary
   depending on the implementation. Firewalls may use network layer,
   transport layer or, in many cases, application-layer criteria to
   make access-control decisions.

   For the purposes of benchmarking firewall performance, this document
   references HTTP 1.1 or higher as the application layer entity. The
   methodologies MAY be used as a template for benchmarking with other
   applications. Since testing may involve proxy based DUT/SUTs, HTTP
   version considerations are discussed in appendix A.

4.4 DUT/SUT Traffic Flows

   Since the number of interfaces are not fixed, the traffic flows will
   be dependent upon the configuration used in benchmarking the
   DUT/SUT. Note that the term "traffic flows" is associated with
   client-to-server requests.

   For Dual-Homed configurations, there are two unique traffic flows:

      Client	   Server
      ------         ------
      Protected   -> Unprotected
      Unprotected -> Protected

   For Tri-Homed configurations, there are three unique traffic flows:

      Client	   Server
      ------         ------
      Protected ->   Unprotected
      Protected ->   DMZ
      Unprotected -> DMZ

4.5 Multiple Client/Server Testing

   One or more clients may target multiple servers for a given
   application. Each virtual client MUST initiate connections in a
   round-robin fashion. For example, if the test consisted of six
   virtual clients targeting three servers, the pattern would be as
   follows:

      Client          Target Server(In order of request)
      #1              1     2     3     1...
	#2              2     3     1     2...
	#3              3     1     2     3...
	#4              1     2     3     1...
	#5              2     3     1     2...
	#6              3     1     2     3...

4.6 Network Address Translation(NAT) Translation (NAT)

   Many firewalls implement network address translation(NAT)[1], a
   function which translates private internet addresses to public
   internet addresses. This involves additional processing on the part
   of the DUT/SUT and may impact performance. Therefore, tests SHOULD
   be ran with NAT disabled and NAT enabled to determine the
   performance differential, if any. The test report MUST indicate
   whether NAT was enabled or disabled.

4.7 Rule Sets

   Rule sets[1] are a collection of access control policies that
   determine which packets the DUT/SUT will forward and which it will
   reject[1]. Since criteria by which these access control policies may
   be defined will vary depending on the capabilities of the DUT/SUT,
   the following is limited to providing guidelines for configuring
   rule sets when benchmarking the performance of the DUT/SUT.

   It is RECOMMENDED that a rule be entered for each host(Virtual
   client). In addition, testing SHOULD be performed using different
   size rule sets to determine its impact on the performance of the
   DUT/SUT. Rule sets MUST be configured in a manner, such that, rules
   associated with actual test traffic are configured at the end of the
   rule set and not the beginning.

   The DUT/SUT SHOULD be configured to deny access to all traffic which
   was not previously defined in the rule set. The test report SHOULD
   include the DUT/SUT configured rule set(s).

4.8 Web Caching

   Some firewalls include caching agents to reduce network load. When
   making a request through a caching agent, the caching agent attempts
   to service the response from its internal memory. The cache itself
   saves responses it receives, such as responses for HTTP GET
   requests. Testing SHOULD be performed with any caching agents on the
   DUT/SUT disabled.

4.9 Authentication

   Access control may involve authentication processes such as user,
   client or session authentication. Authentication is usually
   performed by devices external to the firewall itself, such as an
   authentication server(s) and may add to the latency of the system.
   Any authentication processes MUST be included as part of connection
   setup process.

4.10 TCP Stack Considerations

   Some test instruments allow configuration of one or more TCP stack
   parameters, thereby influencing the traffic flows which will be
   offered and impacting performance measurements. While this document
   does not attempt to specify which TCP parameters should be
   configurable, any such TCP parameter(s) MUST be noted in the test
   report. In addition, when comparing multiple DUT/SUTs, the same TCP
   parameters MUST be used.

5. Benchmarking Tests

5.1 IP Throughput

5.1.1 Objective

   To determine the throughput of network-layer data transversing traversing the
   DUT/SUT, as defined in RFC1242[1]. RFC1242[3]. Note that while RFC1242 uses the
   term frames, which is associated with the link layer, the procedure
   uses the term packets, since it is referencing the network layer.

5.1.2 Setup Parameters

   The following parameters MUST be defined:

      Packet size - Number of bytes in the IP packet, exclusive of any
      link layer header or checksums.

      Test Duration - Duration of the test, expressed in seconds.

5.1.3 Procedure

   The tester MUST offer unicast IP packets traffic to the DUT/SUT at a
   constant rate. The test MAY consist of either bi-directional or
   unidirectional traffic; for example, an emulated client may offer a
   unicast stream of packets to an emulated server, or the tester may
   simulate a client/server exchange by offering bidirectional traffic.

   The test MAY employ an iterative search algorithm. Each iteration
   will involve the tester varying the intended load until the maximum
   rate, at which no packet loss occurs, is found. Since backpressure
   mechanisms may be employed, resulting in the intended load and
   offered load being different, the test SHOULD be performed in either
   a packet based or time based manner as described in RFC2889[7]. RFC2889[5]. As
   with RFC1242, the term packet is used in place of frame. The
   duration of the test portion of each trial MUST be at least 30
   seconds.

   It is RECOMMENDED to perform the throughput measurements with
   different packet sizes. When testing with different packet sizes the
   DUT/SUT configuration MUST remain the same.

5.1.4 Measurement

5.1.4.1 Network Layer

   Throughput - Maximum offered load, expressed in either bits per
   second or packets per second, at which no packet loss is detected.
   The bits to be counted are in the IP packet (header plus payload);
   other fields, such as link-layer headers and trailers, MUST NOT be
   included in the measurement.

   Forwarding Rate - Forwarding rate, expressed in either bits per
   second or packets per second, the device is observed to successfully
   forward to the correct destination interface in response to a
   specified offered load. The bits to be counted are in the IP packet
   (header plus payload); other fields, such as link-layer headers and
   trailers, MUST NOT be included in the measurement.

5.1.4 Reporting Format

   The test report MUST note the packet size(s), test duration,
   throughput and forwarding rate. If the test involved offering
   packets which target more than one segment(Protected, Unprotected
   or DMZ), the report MUST identify the results as an aggregate
   throughput measurement.

   The throughput results SHOULD be reported in the format of a table
   with a row for each of the tested packet sizes.  There SHOULD be
   columns for the packet size, the intended load, the offered load,
   resultant throughput and forwarding rate for each test.

   The intermediate results of the search algorithm MAY be saved in log
   file which includes the packet size, test duration and for each
   iteration:

      - Step Iteration
	- Pass/Fail Status
      - Total packets offered
      - Total packets forwarded
      - Intended load
      - Offered load(If applicable)
      - Forwarding rate

5.2 Concurrent TCP Connection Capacity

5.2.1 Objective

   To determine the maximum number of concurrent TCP connections
   supported through or with the DUT/SUT, as defined in RFC2647[1].
   This test is intended to find the maximum number of entries the
   DUT/SUT can store in its connection table.

5.2.2 Setup Parameters

   The following parameters MUST be defined for all tests:

   5.2.2.1 Transport-Layer Setup Parameters

      Connection Attempt Rate - The aggregate rate, expressed in
      connections per second, at which TCP connection requests are
      attempted. The rate SHOULD be set at or lower than the maximum
      rate at which the DUT/SUT can accept connection requests.

      Aging Time - The time, expressed in seconds, the DUT/SUT will
      keep a connection in its connection table after receiving a TCP
      FIN or RST packet.

   5.2.2.2 Application-Layer Setup Parameters

      Validation Method - HTTP 1.1 or higher MUST be used for this
      test.
      test for both clients and servers. The client and server MUST use
      the same HTTP version.

      Object Size - Defines the number of bytes, excluding any bytes
      associated with the HTTP header, to be transferred in response to
      an HTTP 1.1 or higher GET request.

5.2.3 Procedure

   An iterative search algorithm MAY be used to determine the maximum
   number of concurrent TCP connections supported through or with the
   DUT/SUT.

   For each iteration, the aggregate number of concurrent TCP
   connections attempted by the virtual client(s) will be varied. The
   destination address will be that of the server or that of the NAT
   proxy. The aggregate rate will be defined by connection attempt
   rate, and will be attempted in a round-robin fashion(See 4.5).

   To validate all connections, the virtual client(s) MUST request an
   object using an HTTP 1.1 or higher GET request. The requests MUST be
   initiated on each connection after all of the TCP connections have
   been established.

   When testing proxy-based DUT/SUTs, the virtual client(s) MUST
   request two objects using HTTP 1.1 or higher GET requests. The first
   GET request is required for connection time establishment[1]
   measurements as specified in appendix B. The second request is used
   for validation as previously mentioned. When comparing proxy and
   non-proxy based DUT/SUTs, the test MUST be performed in the same
   manner.

   Between each iteration, it is RECOMMENDED that the tester issue a
   TCP RST referencing each connection attempted for the previous
   iteration, regardless of whether or not the connection attempt was
   successful. The tester will wait for aging time before continuing to
   the next iteration.

5.2.4 Measurements

   5.2.4.1 Application-Layer measurements

      Number of objects requested

      Number of objects returned

   5.2.4.2 Transport-Layer measurements

      Maximum concurrent connections - Total number of TCP connections
      open for the last successful iteration performed in the search
      algorithm.

      Minimum connection establishment time - Lowest TCP connection
      establishment time measured as defined in appendix B.

      Maximum connection establishment time - Highest TCP connection
      establishment time measured as defined in appendix B.

      Average connection establishment time - The mean of all
      measurements of connection establishment times.

      Aggregate connection establishment time - The total of all
      measurements of connection establishment times.

5.2.5 Reporting Format

   5.2.5.1 Application-Layer Reporting:

      The test report MUST note the object size, number of completed
      requests and number of completed responses.

      The intermediate results of the search algorithm MAY be reported
      in a tabular format with a column for each iteration. There
      SHOULD be rows for the number of requests attempted, number and
      percentage requests completed, number of responses attempted,
      number and percentage of responses completed. The table MAY be
      combined with the transport-layer reporting, provided that the
      table identify this as an application layer measurement.

   Version information:

      The test report MUST note the version of HTTP client(s) and
      server(s).

5.2.5.2 Transport-Layer Reporting:

   The test report MUST note the connection attempt rate, aging time,
   minimum TCP connection establishment time, maximum TCP connection
   establishment time, average connection establishment time, aggregate
   connection establishment time and maximum concurrent connections
   measured.

   The intermediate results of the search algorithm MAY be reported in
   the format of a table with a column for each iteration. There SHOULD
   be rows for the total number of TCP connections attempted, number
   and percentage of TCP connections completed, minimum TCP connection
   establishment time, maximum TCP connection establishment time,
   average connection establishment time and the aggregate connection
   establishment time.

5.3 Maximum TCP Connection Establishment Rate

5.3.1 Objective

   To determine the maximum TCP connection establishment rate through
   or with the DUT/SUT, as defined by RFC2647[1]. This test is intended
   to find the maximum rate the DUT/SUT can update its connection
   table.

5.3.2 Setup Parameters

   The following parameters MUST be defined for all tests:

   5.3.2.1 Transport-Layer Setup Parameters
      Number of Connections - Defines the aggregate number of TCP
      connections that must be established.

      Aging Time - The time, expressed in seconds, the DUT/SUT will
      keep a connection in it's state table after receiving a TCP FIN
      or RST packet.

   5.3.2.2 Application-Layer Setup Parameters

      Validation Method - HTTP 1.1 or higher MUST be used for this
      test.
      test for both clients and servers. The client and server MUST use
      the same HTTP version.

      Object Size - Defines the number of bytes, excluding any bytes
      associated with the HTTP header, to be transferred in response to
      an HTTP 1.1 or higher GET request.

5.3.3 Procedure

   An iterative search algorithm MAY be used to determine the maximum
   rate at which the DUT/SUT can accept TCP connection requests.

   For each iteration, the aggregate rate at which TCP connection
   requests are attempted by the virtual client(s) will be varied. The
   destination address will be that of the server or that of the NAT
   proxy. The aggregate number of connections, defined by number of
   connections, will be attempted in a round-robin fashion(See 4.5).

   The same application-layer object transfers required for validation
   and establishment time measurements as described in the concurrent
   TCP connection capacity test MUST be performed.

   Between each iteration, it is RECOMMENDED that the tester issue a
   TCP RST referencing each connection attempted for the previous
   iteration, regardless of whether or not the connection attempt was
   successful. The tester will wait for aging time before continuing to
   the next iteration.

5.3.4 Measurements

   5.3.4.1 Application-Layer measurements

      Number of objects requested

      Number of objects returned

   5.3.4.2 Transport-Layer measurements

      Highest connection rate - Highest rate, in connections per
      second, for which all connections successfully opened in the
      search algorithm.

      Minimum connection establishment time - Lowest TCP connection
      establishment time measured as defined in appendix B.

      Maximum connection establishment time - Highest TCP connection
      establishment time measured as defined in appendix B.

      Average connection establishment time - The mean of all
      measurements of connection establishment times.

      Aggregate connection establishment time - The total of all
      measurements of connection establishment times.

5.3.5 Reporting Format

   5.3.5.1 Application-Layer Reporting:

      The test report MUST note object size(s), number of completed
      requests and number of completed responses.

      The intermediate results of the search algorithm MAY be reported
      in a tabular format with a column for each iteration. There
      SHOULD be rows for the number of requests attempted, number and
      percentage requests completed, number of responses attempted,
      number and percentage of responses completed. The table MAY be
      combined with the transport-layer reporting, provided that the
      table identify this as an application layer measurement.

      Version information:

      The test report MUST note the version of HTTP client(s) and
      server(s).

   5.3.5.2 Transport-Layer Reporting:

      The test report MUST note the number of connections, aging time,
      minimum TCP connection establishment time, maximum TCP connection
      establishment time, average connection establishment time,
      aggregate connection establishment time and highest connection
      rate measured.

      The intermediate results of the search algorithm MAY be reported
      in the format of a table with a column for each iteration. There
      SHOULD be rows for the connection attempt rate, total number of
      TCP connections attempted, total number of TCP connections
      completed, minimum TCP connection establishment time, maximum TCP
      connection establishment time, average connection establishment
      time and the aggregate connection establishment time.

5.4 Maximum TCP Connection Tear Down Rate

5.4.1 Objective

   To determine the maximum TCP connection tear down rate through or
   with the DUT/SUT, as defined by RFC2647[1].

5.4.2 Setup Parameters

   Number of Connections - Defines the number of TCP connections that
   will be attempted to be torn down.

   Aging Time - The time, expressed in seconds, the DUT/SUT will keep a
   connection in it's state table after receiving a TCP FIN or RST
   packet.

   Close Method - Defines method for closing TCP connections. The test
   MUST be performed with either a three-way or four-way handshake. In
   a four-way handshake, each side sends separate FIN and ACK messages.
   In a three-way handshake, one side sends a combined FIN/ACK message
   upon receipt of a FIN.

   Close Direction - Defines whether closing of connections are to be
   initiated from the client or from the server.

5.4.3 Procedure

   An iterative search algorithm MAY be used to determine the maximum
   TCP connection tear down rate. The test iterates through different
   TCP connection tear down rates with a fixed number of TCP
   connections.

   In the case of proxy based DUT/SUTs, the DUT/SUT will itself receive
   the ACK in response to issuing a FIN packet to close its side of the
   TCP connection. For validation purposes, the virtual client or
   server, whichever is applicable, MAY verify that the DUT/SUT
   received the final ACK by re-transmitting the final ACK. A TCP RST
   should be received in response to the retransmitted ACK.

   Between each iteration, it is RECOMMENDED that the virtual client(s)
   or server(s), whichever is applicable, issue a TCP RST referencing
   each connection which was attempted to be torn down, regardless of
   whether or not the connection tear down attempt was successful. The
   test will wait for aging time before continuing to the next
   iteration.

5.4.4 Measurements

   Highest connection tear down rate - Highest rate, in connections per
   second, for which all TCP connections were successfully torn down in
   the search algorithm.

   The following tear down time[1] measurements MUST only include
   connections for which both sides of the connection were successfully
   torn down. For example, tear down times for connections which are
   left in a FINWAIT-2[8] state should not be included:

   Minimum connection tear down time - Lowest TCP connection tear down
   time measured as defined in appendix C.

   Maximum connection tear down time - Highest TCP connection tear down
   time measured as defined in appendix C.

   Average connection tear down time - The mean of all measurements of
   connection tear down times.

   Aggregate connection tear down time - The total of all measurements
   of connection tear down times.

5.4.5 Reporting Format

   The test report MUST note the number of connections, aging time,
   close method, close direction, minimum TCP connection tear down
   time, maximum TCP connection tear down time, average TCP connection
   tear down time and the aggregate TCP connection tear down time and
   highest connection tear down rate measured.

   The intermediate results of the search algorithm MAY be reported in
   the format of a table with a column for each iteration. There SHOULD
   be rows for the number of TCP tear downs attempted, number and
   percentage of TCP connection tear downs completed, minimum TCP
   connection tear down time, maximum TCP connection tear down time,
   average TCP connection tear down time, aggregate TCP connection tear
   down time and validation failures, if required.

5.5 Denial Of Service Handling

5.5.1 Objective

   To determine the effect of a denial of service attack on a DUT/SUT
   TCP connection establishment and/or HTTP transfer rates. The denial
   of service handling test MUST be run after obtaining baseline
   measurements from sections 5.3 and/or 5.6.

   The TCP SYN flood attack exploits TCP's three-way handshake
   mechanism by having an attacking source host generate TCP SYN
   packets with random source addresses towards a victim host, thereby
   consuming that host's resources.

5.5.2 Setup Parameters

   Use the same setup parameters as defined in section 5.3.2 or 5.6.2,
   depending on whether testing against the baseline TCP connection
   establishment rate test or HTTP transfer rate test, respectfully.

   In addition, the following setup parameters MUST be defined:

   SYN attack rate - Rate, expressed in packets per second, at which
   the server(s) or NAT proxy address is targeted with TCP SYN packets.

5.5.3 Procedure

   Use the same procedure as defined in section 5.3.3 or 5.6.3,
   depending on whether testing against the baseline TCP connection
   establishment rate or HTTP transfer rate test, respectfully. In
   addition, the tester will generate TCP SYN packets targeting the
   server(s) IP address or NAT proxy address at a rate defined by SYN
   attack rate.

   The tester originating the TCP SYN attack MUST be attached to the
   unprotected network. In addition, the tester MUST not respond to the
   SYN/ACK packets sent by target server or NAT proxy in response to
   the SYN packet.

   Some firewalls employ mechanisms to guard against SYN attacks. If
   such mechanisms exist on the DUT/SUT, tests SHOULD be run with these
   mechanisms enabled and disabled to determine how well the DUT/SUT
   can maintain, under such attacks, the baseline connection
   establishment rates and HTTP transfer rates determined in section
   5.3 and section 5.6, respectively.

5.5.4 Measurements

   Perform the same measurements as defined in section 5.3.4 or 5.6.4,
   depending on whether testing against the baseline TCP connection
   establishment rate test or HTTP transfer rate, respectfully.

   In addition, the tester SHOULD track TCP SYN packets associated with
   the SYN attack which the DUT/SUT forwards on the protected or DMZ
   interface(s).

5.5.5 Reporting Format

   The test SHOULD use the same reporting format as described in
   section 5.3.5 or 5.6.5, depending on whether testing against the
   baseline TCP connection establishment rate test or HTTP transfer
   rate, respectfully.

   In addition, the report MUST indicate a denial of service handling
   test, SYN attack rate, number of TCP SYN attack packets transmitted
   and the number of TCP SYN attack packets forwarded by the DUT/SUT.
   The report MUST indicate whether or not the DUT has any SYN attack
   mechanisms enabled.

5.6 HTTP Transfer Rate

5.6.1 Objective

   To determine the transfer rate of HTTP requested object transversing traversing
   the DUT/SUT.

5.6.2 Setup Parameters

   The following parameters MUST be defined for all tests:

   5.6.2.1 Transport-Layer Setup Parameters

      Number of connections - Defines the aggregate number of
      connections attempted. The number SHOULD be a multiple of the
      number of virtual clients participating in the test.

      Close Method - Defines the method for closing TCP connections.
      The test MUST be performed with either a three-way or four-way
      handshake. In a four-way handshake, each side sends separate FIN
      and ACK messages. In a three-way handshake, one side sends a
      combined FIN/ACK message upon receipt of a FIN.

      Close Direction - Defines whether closing of connections are to
      be initiated from the client or from the server.

   5.6.2.2 Application-Layer Setup Parameters

      Session Type - The virtual clients/servers MUST use HTTP 1.1 or
      higher. The client and server MUST use the same HTTP version.

      GET requests per connection - Defines the number of HTTP 1.1 or
      higher GET requests attempted per connection.

      Object Size - Defines the number of bytes, excluding any bytes
      associated with the HTTP header, to be transferred in response to
      an HTTP 1.1 or higher GET request.

5.6.3 Procedure

   Each HTTP 1.1 or higher virtual client will request one or more
   objects from an HTTP 1.1 or higher server using one or more HTTP
   GET requests over each connection. The aggregate number of
   connections attempted, defined by number of connections, MUST be
   evenly divided among all of the participating virtual clients.

   If the virtual client(s) make multiple HTTP GET requests per
   connection, it MUST request the same object size for each GET
   request. Multiple iterations of this test may be run with objects
   of different sizes.

5.6.4 Measurements

   5.6.4.1 Application-Layer measurements

      Average Transfer Rate - The average transfer rate of the DUT/SUT
      MUST be measured and shall be referenced to the requested
      object(s). The measurement will start on transmission of the
      first bit of the first requested object and end on transmission
      of the last bit of the last requested object. The average
      transfer rate, in bits per second, will be calculated using the
      following formula:

                               OBJECTS * OBJECTSIZE * 8
      TRANSFER RATE(bit/s) =  --------------------------
                                      DURATION

      OBJECTS - Total number of objects successfully transferred across
                all connections.

      OBJECTSIZE - Object size in bytes

      DURATION - Aggregate transfer time based on aforementioned time
                 references.

   5.6.4.2 Measurements at or below the Transport-Layer

      The following measurements SHOULD be performed for each
      connection-oriented protocol:

      Goodput[1] - Goodput as defined in section 3.17 of RFC2647.
      Measurements MUST only reference the protocol payload, excluding
      any of the protocol header. In addition, the tester MUST exclude
      any bits associated with the connection establishment, connection
      tear down, security associations[1] or connection maintenance[1].
      Since connection-oriented protocols require that data be
      acknowledged, the offered load[6] load[4] will be varying. Therefore, the
      tester should measure the average forwarding rate over the
      duration of the test. Measurement should start on transmission of
      the first bit of the payload of the first datagram and end on
      transmission of the last bit of the payload of the last datagram.

      Number of bytes transferred - Total payload bytes transferred.

      Number of Timeouts - Total number of timeout events.

      Retransmitted bytes - Total number of retransmitted bytes.

5.6.5 Reporting Format

   5.6.5.1 Application-Layer reporting

      The test report MUST note number of GET requests per connection
      and object size(s).

      The transfer rate results SHOULD be reported in tabular form with
      a column for each of the object sizes tested. There SHOULD be a
      row for the object size, number and percentage of completed requests, number
      and percentage of completed responses, and the resultant transfer
      rate for each iteration of the test.

      Failure analysis:

      The test report SHOULD indicate the number and percentage of HTTP
      GET request and responses that failed to complete.

      Version information:

      The test report MUST note the version of HTTP client(s) and
      server(s).

   5.6.5.2 Transport-Layer and below reporting

      The test report MUST note the number of connections, close
      method, close direction and the protocol for which the
      measurement was made.

      The results SHOULD be reported in tabular form for each of the
      HTTP object sizes tested. There SHOULD be a row for the HTTP
      object size, resultant goodput, total
      bytes transferred, total timeouts, total retransmitted bytes and total bytes transferred.
      and resultant goodput. Note that total bytes refers to total
      datagram payload bytes transferred. The table MAY be combined
      with the application layer reporting, provided the table clearly
      identify the protocol for which the measurement was made.

      Failure analysis:

      The test report SHOULD indicate the number and percentage of
      connection establishment failures as well as number and
      percentage of TCP tear down failures.

      It is RECOMMENDED that the report include a graph to plot the
      distribution of both connection establishment failures and
      connection tear down failures. The x coordinate SHOULD be the
      elapsed test time, the y coordinate SHOULD be the number of
      failures for a given sampling period. There SHOULD be two lines
      on the graph, one for connection failures and one for tear down
      failures. The graph MUST note the sampling period.

5.7 Maximum HTTP Transaction Rate

5.7.1 Objective

   Determine the maximum transaction rate the DUT/SUT can sustain. This
   test is intended to find the maximum rate at which users can access
   objects.

5.7.2 Setup Parameters

   5.7.2.1 Transport-Layer Setup Parameters

      Close Method - Defines method for closing TCP connections. The
      test MUST be performed with either a three-way or four-way
      handshake. In a four-way handshake, each side sends separate FIN
      and ACK messages. In a three-way handshake, one side sends a
      combined FIN/ACK message upon receipt of a FIN.

      Close Direction - Defines whether closing of connections are to
      be initiated from the client or from the server.

   5.7.2.2 Application-Layer Setup Parameters

      Session Type - HTTP 1.1 or higher MUST be used for this test. The
      client and server MUST use the same HTTP version.

      Test Duration - Time, expressed in seconds, for which the
      virtual client(s) will sustain the attempted GET request rate.
      It is RECOMMENDED that the duration be at least 30 seconds.

      Requests per connection - Number of object requests per
      connection.

      Object Size - Defines the number of bytes, excluding any bytes
      associated with the HTTP header, to be transferred in response to
      an HTTP 1.1 or higher GET request.

5.7.3 Procedure

   An iterative search algorithm MAY be used to determine the maximum
   transaction rate that the DUT/SUT can sustain.

   For each iteration, HTTP 1.1 or higher virtual client(s) will vary
   the aggregate GET request rate offered to HTTP 1.1 or higher
   server(s). The virtual client(s) will maintain the offered request
   rate for the defined test duration.

   If the virtual client(s) make multiple HTTP GET requests per
   connection, it MUST request the same object size for each GET
   request. Multiple tests MAY be performed with different object
   sizes.

5.7.4 Measurements

   Maximum Transaction Rate - The maximum rate at which all
   transactions -- that is all requests/responses cycles -- are
   completed.

   Transaction Time - The tester SHOULD measure minimum, maximum and
   average transaction times. The transaction time will start when the
   virtual client issues the GET request and end when the requesting
   virtual client receives the last bit of the requested object.

5.7.5 Reporting Format

   5.7.5.1 Application-Layer reporting

      The test report MUST note the test duration, object size,
      requests per connection and the measured minimum, connection, minimum transaction time, maximum and
      transaction time, average transaction rate. time and maximum
      transaction rate measured

      The intermediate results of the search algorithm MAY be reported
      in a table format with a column for each iteration. There SHOULD
      be rows for the GET request attempt rate, number of requests
      attempted, number and percentage of requests completed, number of
      responses attempted, number and percentage of responses
      completed, minimum transaction time, average transaction time and
      maximum transaction time.

      Version information:

      The test report MUST note the version of HTTP client(s) and
      server(s).

   5.7.5.2 Transport-Layer

      The test report MUST note the close method, close direction,
      number of connections established and number of connections torn
      down.

      The intermediate results of the search algorithm MAY be reported
      in a table format with a column for each iteration. There SHOULD
      be rows for the number of connections attempted, number and
      percentage of connections completed, number and percentage of
      connection tear downs completed. The table MAY be combined with
      the application layer reporting, provided the table identify this
      as transport layer measurement.

5.8 Illegal Traffic Handling

 5.8.1 Objective

   To character characterize the behavior of the DUT/SUT when presented with a
   combination of both legal and Illegal[1] traffic. Note that Illegal
   traffic does not refer to an attack, but traffic which has been
   explicitly defined by a rule(s) to drop.

5.8.2 Setup Parameters

   Setup parameters will use the same parameters as specified in the
   HTTP transfer rate test(Section 5.6.2). In addition, the following
   setup parameters MUST be defined:

   Illegal traffic percentage - Percentage of HTTP 1.1 or higher
   connections which have been explicitly defined in a rule(s) to drop.

5.8.3 Procedure

   Each HTTP 1.1 or higher client will request one or more objects from
   an HTTP 1.1 or higher server using one or more HTTP GET requests
   over each connection. The aggregate number of connections attempted,
   defined by number of connections, MUST be evenly divided among all
   of the participating virtual clients.

   The virtual client(s) MUST offer the connection requests, both legal
   and illegal, in an evenly distributed manner. Many firewalls have
   the capability to filter on different traffic criteria( IP
   addresses, Port numbers, etc). Multiple iterations of this test MAY
   be run with the DUT/SUT configured to filter on different traffic
   criteria.

5.8.4 Measurements

   The same measurements as defined in HTTP transfer rate test(Section
   5.6.4) SHOULD be performed. Any forwarding rate measurements MUST
   only include bits which are associated with legal traffic.

 5.8.5 Reporting Format

   Test reporting format SHOULD be the same as specified in the HTTP
   transfer rate test(Section 5.6.5).

   In addition, the report MUST note the percentage of illegal HTTP
   connections.

   Failure analysis:

   Test report MUST note the number and percentage of illegal
   connections that were allowed by the DUT/SUT.

5.9 IP Fragmentation Handling

5.9.1 Objective

   To determine the performance impact when the DUT/SUT is presented
   with IP fragmented[5] fragmented traffic. IP packets which have been
   fragmented, due to crossing a network that supports a smaller
   MTU(Maximum Transmission Unit) than the actual IP packet, may
   require the firewall to perform re-assembly prior to the rule set
   being applied.

   While IP fragmentation is a common form of attack, either on the
   firewall itself or on internal hosts, this test will focus on
   determining how the additional processing associated with the
   re-assembly of the packets have on the forwarding rate of the
   DUT/SUT. RFC 1858 addresses some fragmentation attacks that
   get around IP filtering processes used in routers and hosts.

5.9.2 Setup Parameters

   The following parameters MUST be defined.

   5.9.2.1 Non-Fragmented Traffic Parameters

      Setup parameters will be the same as defined in the HTTP transfer
      rate test(Sections 5.6.2.1 and 5.6.2.2).

   5.9.2.2 Fragmented Traffic Parameters

      Packet size - Number of bytes in the IP/UDP packet, exclusive of
      link-layer headers and checksums, prior to fragmentation.

      MTU - Maximum transmission unit, expressed in bytes. For testing
      purposes, this MAY be configured to values smaller than the MTU
      supported by the link layer.

      Intended Load -  Intended load, expressed as percentage of media
      utilization.

5.9.3 Procedure

   Each HTTP 1.1 or higher client will request one or more objects from
   an HTTP 1.1 or higher server using one or more HTTP GET requests
   over each connection. The aggregate number of connections attempted,
   defined by number of connections, MUST be evenly divided among all
   of the participating virtual clients. If the virtual client(s) make
   multiple HTTP GET requests per connection, it MUST request the same
   object size for each GET request.

   A tester attached to the unprotected side of the network, will offer
   a unidirectional stream of unicast fragmented IP/UDP traffic,
   targeting a server attached to either the protected or DMZ segment.
   The tester MUST offer the unidirectional stream over the duration of
   the test -- that is, duration over which the HTTP traffic is being
   offered.

   Baseline measurements SHOULD be performed with IP filtering deny
   rule(s) to filter fragmented traffic. If the DUT/SUT has logging
   capability, the log SHOULD be checked to determine if it contains
   the correct information regarding the fragmented traffic.

   The test SHOULD be repeated with the DUT/SUT rule set changed to
   allow the fragmented traffic through. When running multiple
   iterations of the test, it is RECOMMENDED to vary the MTU while
   keeping all other parameters constant.

   Then setup the DUT/SUT to the policy or rule set the manufacturer
   required to be defined to protect against fragmentation attacks and
   repeat the measurements outlined in the baseline procedures.

5.9.4 Measurements

   Tester SHOULD perform the same measurements as defined in HTTP
   test(Section 5.6.4).

   Transmitted UDP/IP Packets - Number of UDP packets transmitted by
   client.

   Received UDP/IP Packets - Number of UDP/IP Packets received by
   server.

5.9.5 Reporting Format

   5.10.1 Non-Fragmented Traffic

      The test report SHOULD be the same as described in section 5.6.5.
      Note that any forwarding rate measurements for the HTTP traffic
      excludes any bits associated with the fragmented traffic which
      may be forward by the DUT/SUT.

   5.9.2 Fragmented Traffic

      The test report MUST note the packet size, MTU size, intended
      load, number of UDP/IP packets transmitted and number of UDP/IP
      packets forwarded. The test report SHOULD also note whether or
      not the DUT/SUT forwarded the offered UDP/IP traffic fragmented.

5.10 Latency

5.10.1 Objective

   To determine the latency of network-layer or application-layer data
   traversing the DUT/SUT. RFC 1242 [3] defines latency.

5.10.2 Setup Parameters

   The following parameters MUST be defined:

   5.10.2.1 Network-layer Measurements

      Packet size, expressed as the number of bytes in the IP packet,
      exclusive of link-layer headers and checksums.

      Intended load, expressed as percentage of media utilization.

      Test duration, expressed in seconds.

      Test instruments MUST generate packets with unique timestamp
      signatures.

   5.10.2.2 Application-layer Measurements

      Object Size - Defines the number of bytes, excluding any bytes
      associated with the HTTP header, to be transferred in response to
      an HTTP 1.1 or higher GET request. Testers SHOULD use the minimum
      object size supported by the media, but MAY use other object
      sizes as well.

      Connection type. The tester MUST use one HTTP 1.1 or higher
      connection for latency measurements.

      Number of objects requested.

      Number of objects transferred.

      Test duration, expressed in seconds.

      Test instruments MUST generate packets with unique timestamp
      signatures.

   5.10.3 Network-layer procedure

      A client will offer a unidirectional stream of unicast packets to
      a server. The packets MUST use a connectionless protocol like IP
      or UDP/IP.

      The tester MUST offer packets in a steady state. As noted in the
      latency discussion in RFC 2544 [4], [2], latency measurements MUST be
      taken at the throughput level -- that is, at the highest offered
      load with zero packet loss. Measurements taken at the throughput
      level are the only ones that can legitimately be termed latency.

      It is RECOMMENDED that implementers use offered loads not only at
      the throughput level, but also at load levels that are less than
      or greater than the throughput level. To avoid confusion with
      existing terminology, measurements from such tests MUST be labeled
      as delay rather than latency.

      It is RECOMMENDED to perform the latency measurements with
      different packet sizes. When testing with different packet sizes
      the DUT/SUT configuration MUST remain the same.

      If desired, the tester MAY use a step test in which offered loads
      increment or decrement through a range of load levels.

      The duration of the test portion of each trial MUST be at least
      30 seconds.

5.10.4 Application layer procedure

   An HTTP 1.1 or higher client will request one or more objects from
   an HTTP 1.1 or higher server using one or more HTTP GET requests. If
   the tester makes multiple HTTP GET requests, it MUST request the
   same-sized object each time. Testers may run multiple iterations of
   this test with objects of different sizes.

   Implementers MAY configure the tester to run for a fixed duration.
   In this case, the tester MUST report the number of objects requested
   and returned for the duration of the test. For fixed-duration tests
   it is RECOMMENDED that the duration be at least 30 seconds.

5.10.5 Measurements

   Minimum delay - The smallest delay incurred by data traversing the
   DUT/SUT at the network layer or application layer, as appropriate.

   Maximum delay - The largest delay incurred by data traversing the
   DUT/SUT at the network layer or application layer, as appropriate.

   Average delay - The mean of all measurements of delay incurred by
   data traversing the DUT/SUT at the network layer or application
   layer, as appropriate.

   Delay distribution - A set of histograms of all delay measurements
   observed for data traversing the DUT/SUT at the network layer or
   application layer, as appropriate.

   5.10.6 Network-layer reporting format

   The test report MUST note the packet size(s), offered load(s) and
   test duration used.

   The latency results SHOULD be reported in the format of a table with
   a row for each of the tested packet sizes.  There SHOULD be columns
   for the packet size, the intended rate, the offered rate, and the
   resultant latency or delay values for each test.

5.10.7 Application-layer reporting format

   The test report MUST note the object size(s) and number of requests
   and responses completed. If applicable, the report MUST note the
   test duration if a fixed duration was used.

   The latency results SHOULD be reported in the format of a table with
   a row for each of the object sizes. There SHOULD be columns for the
   object size, the number of completed requests, the number of
   completed responses, and the resultant latency or delay values for
   each test.

   Failure analysis:

   The test report SHOULD indicate the number and percentage of HTTP
   GET request or responses that failed to complete within the test
   duration.

   Version information:

   The test report MUST note the version of HTTP client and server.

6. References

Normative References

  [1] D. Newman, "Benchmarking Terminology for Firewall Devices",
      RFC 2647, August 1999.

  [2] R. Fielding, J. Gettys, S. Bradner, J. Mogul, H Frystyk, L.Masinter,
      P. Leach, T. Berners-Lee , "Hypertext Transfer Protocol -
      HTTP/1.1", McQuaid, "Benchmarking Methodology for Network
      Interconnect Devices," RFC 2616 June 2544, March 1999.

  [3] S. Bradner, editor. "Benchmarking Terminology for Network
      Interconnection Devices," RFC 1242, July 1991.

  [4] S. Bradner, J. McQuaid, "Benchmarking Methodology for Network
      Interconnect Devices," RFC 2544, March 1999.

  [5] David C. Clark, "IP Datagram Reassembly Algorithm", RFC 815 ,
      July 1982.

  [6] Mandeville, R., "Benchmarking Terminology for LAN Switching
      Devices", RFC 2285, February 1998.

  [7]

  [5] Mandeville, R., Perser,J., "Benchmarking Methodology for LAN
      Switching Devices", RFC 2889, August 2000.

Informative References

  [6] R. Fielding, J. Gettys, J. Mogul, H Frystyk, L.Masinter,
      P. Leach, T. Berners-Lee , "Hypertext Transfer Protocol -
      HTTP/1.1", RFC 2616, June 1999.

  [7] David C. Clark, "IP Datagram Reassembly Algorithm", RFC 815 ,
      July 1982.

  [8] Postel, J. (ed.), "Internet Protocol - DARPA Internet Program
      Protocol Specification", "Transmission Control Protocol", RFC 793,
      USC/Information Sciences Institute, September 1981.

7. Security Considerations

   The primary goal of this document is to provide methodologies in
   benchmarking firewall performance. While there is some overlap
   between performance and security issues, assessment of firewall
   security is outside the scope of this document.

8. Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.

9. Authors' Addresses

   Brooks Hickman
   Spirent Communications
   26750 Agoura Road
   Calabasas, CA 91302
   USA

   Phone: + 1 818 676 2412
   Email: brooks.hickman@spirentcom.com

   David Newman
   Network Test Inc.
   31324 Via Colinas, Suite 113
   Westlake Village, CA 91362-6761
   USA

   Phone: + 1 818 889-0011
   Email: dnewman@networktest.com

   Saldju Tadjudin
   Spirent Communications
   26750 Agoura Road
   Calabasas, CA 91302
   USA

   Phone: + 1 818 676 2468
   Email: Saldju.Tadjudin@spirentcom.com

   Terry Martin
   GVNW Consulting Inc.
   8050 SW Warm Springs Road
   Tualatin Or. 97062
   USA

   Phone: + 1 503 612 4422
   Email: tmartin@gvnw.com

APPENDIX A: HTTP(HyperText HTTP (HyperText Transfer Protocol)

   The most common versions of HTTP in use today are HTTP/1.0 and
   HTTP/1.1 with the main difference being in regard to persistent
   connections.  HTTP 1.0, by default, does not support persistent
   connections. A separate TCP connection is opened up for each
   GET request the client wants to initiate and closed after the
   requested object transfer is completed. While some implementations
   HTTP/1.0 supports persistence through the use of a keep-alive,
   there is no official specification for how the keep-alive operates.
   In addition, HTTP 1.0 proxies do support persistent connection as
   they do not recognize the connection header.

   HTTP/1.1, by default, does support persistent connection and
   is therefore the version that is referenced in this methodology.
   Proxy based DUT/SUTs may monitor the TCP connection and after a
   timeout, close the connection if no activity is detected. The
   duration of this timeout is not defined in the HTTP/1.1
   specification and will vary between DUT/SUTs. If the DUT/SUT
   closes inactive connections, the aging timer on the DUT SHOULD
   be configured for a duration that exceeds the test time.

   While this document cannot foresee future changes to HTTP
   and it impact on the methodologies defined herein, such
   changes should be accommodated for so that newer versions of
   HTTP may be used in benchmarking firewall performance.

APPENDIX B: Connection Establishment Time Measurements

  Some connection oriented protocols, such as TCP, involve an odd
  number of messages when establishing a connection. In the case of
  proxy based DUT/SUTs, the DUT/SUT will terminate the connection,
  setting up a separate connection to the server. Since, in such
  cases, the tester does not own both sides of the connection,
  measurements will be made two different ways. While the following
  describes the measurements with reference to TCP, the methodology
  may be used with other connection oriented protocols which involve
  an odd number of messages.

  When testing non-proxy based DUT/SUTs , the establishment time shall
  be directly measured and is considered to be from the time the first
  bit of the first SYN packet is transmitted by the client to the
  time the last bit of the final ACK in the three-way handshake is
  received by the target server.

  If the DUT/SUT is proxy based, the connection establishment time is
  considered to be from the time the first bit of the first SYN packet
  is transmitted by the client to the time the client transmits the
  first bit of the first acknowledged TCP datagram(t4-t0 in the
  following timeline).

      t0: Client sends a SYN.
      t1: Proxy sends a SYN/ACK.
      t2: Client sends the final ACK.
      t3: Proxy establishes separate connection with server.
      t4: Client sends TCP datagram to server.
      *t5: Proxy sends ACK of the datagram to client.

* While t5 is not considered part of the TCP connection
  establishment, acknowledgement of t4 must be received for the
  connection to be considered successful.

APPENDIX C: Connection Tear Time Measurements

  While TCP connections are full duplex, tearing down of such
  connections are performed in a simplex fashion -- that is - FIN
  segments are sent by each host/device terminating each side of
  the TCP connection.

  When making connection tear down times measurements, such
  measurements will be made from the perspective of the entity - that
  is -- virtual client/server initiating the connection tear down
  request. In addition, the measurement will be performed in the same
  manner, independent of whether or not the DUT/SUT is proxy-based.
  The connection tear down will be considered the interval between the
  transmission of the first bit of the first TCP FIN packet transmitted
  by the virtual client or server, whichever is applicable, requesting
  a connection tear down to receipt of the last bit of the
  corresponding ACK packet on the same virtual client/server interface.

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