Network Working Group
   INTERNET-DRAFT
   Expires in: December 2003 April 2004
                                                   Scott Poretsky
                                                   Avici Systems

                                                   June
                                                   Quarry Technologies

                                                   Brent Imhoff
						   		   Wiltel Communications

						   		   October 2003

             	  Terminology for Benchmarking
		      IGP Data Plane Route Convergence

		<draft-ietf-bmwg-igp-dataplane-conv-term-00.txt>

		<draft-ietf-bmwg-igp-dataplane-conv-term-01.txt>

   Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force  (IETF), its areas, and its working groups.  Note that
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   as reference material or to cite them other than as "work in
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   http://www.ietf.org/ietf/1id-abstracts.txt

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   Table of Contents

     1. Introduction ...............................................2
     2. Existing definitions .......................................2
     3. Term definitions............................................2 definitions............................................3
	3.1 Network Convergence.....................................2 Convergence.......................................3
 	3.2 Protocol Convergence....................................3 Convergence......................................3
 	3.3 Route Convergence.......................................3 Convergence.........................................4
	3.4 Full Route Convergence Time.............................4 Event.........................................4
	3.5 Route Convergence Packet Loss...........................5 Full Convergence..........................................4
	3.6 Average Route Convergence Time..........................5 Packet Loss...................................5
	3.7 Route Convergence Event Slope...........................6 Instant.................................5
	3.8 Route Convergence Recovery Slope........................6 Transition...........................6
	3.9  Reroute Rate-Derived Convergence Time...............................7 Time.............................6
	3.10 Local Interface........................................7 Convergence Recovery Instant.............................7
	3.11 Neighbor Interface.....................................8 Convergence Event Transition.............................7
	3.12 Loss-Derived Convergence Time............................8
           	      IGP Data Plane Route Convergence

	3.13 Route Convergence Time...................................9
	3.14 Restoration Convergence Time.............................9
	3.15 Packet Sampling Interval.................................10
	3.16 Local Interface..........................................10
	3.17 Neighbor Interface.......................................10
	3.18 Remote Interface.......................................8 Interface.........................................11
	3.19 Preferred Egress Interface...............................11
	3.20 Next-Best Egress Interface...............................12
     4. Security Considerations.....................................8 Considerations.....................................12
     5. References..................................................9
           		    	    IGP Route Convergence

     7. References..................................................12
     6. Author's Address............................................9
     8. Address............................................12
     7. Full Copyright Statement....................................9 Statement....................................13

   1. Introduction
   This draft describes the terminology for benchmarking IGP Route
   Convergence.  The motivation and applicability for this
   benchmarking is provided in [1].  The methodology to be used for
   this benchmarking is described in [2].  The methodology and
   terminology to be used for benchmarking route convergence can be
   applied to any link-state IGP such as ISIS [3] and OSPF [4].  The
   data plane is measured to obtain the black-box (externally observable)
   convergence benchmarking metrics.  The purpose of this document is
   to introduce new terms required to complete execution of the IGP
   Route Convergence Methodology [2].

   An example of Route Convergence as observed and measured from the
   data plane is shown in Figure 1.  The graph in Figure 1 shows
   Forwarding Rate versus Time.  Time 0 on the X-axis is on the far
   right of the graph.  The components of the graph and metrics are
   defined in the Term Definitions section of this document.

		            Recovery  Convergence Event   Time = 0sec
	Maximum		     ^		 ^		    ^
	Forwarding Rate--> ----\    Packet   /---------------
					\    Loss   /<----Convergence
	      Convergence------->\	     /  	  Event Transition
	Recovery Transition	  \	    /
				   	   \_____/<------100% Packet Loss

	X-axis = Time
	Y-axis = Forwarding Rate

			Figure 1. Convergence Graph

   2.  Existing definitions
   For the sake of clarity and continuity this RFC adopts the template
   for definitions set out in Section 2 of RFC 1242.  Definitions are
   indexed and grouped together in sections for ease of reference.
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in
   this document are to be interpreted as described in RFC 2119.

           	      IGP Data Plane Route Convergence

   3. Term definitions Definitions

   3.1 Network Convergence

	Definition:
	The completion of updating of all routing tables, including the
	FIB, in all routers throughout the network.

	Discussion:
	Network Convergence can be approximated to the sum of Route
Convergence for all routers in the network.  Network Convergence
	can only be determined by the occurrence of packet loss or stale
	forwarding due to an out-of-date FIB.

	Measurement Units:
	Converged or Not Converged
	N/A

	Issues:
	None

	See Also:
	Protocol Convergence
	Route Convergence
           	      IGP Data Plane Route Convergence

   3.2 Protocol Convergence

	Definition:
	The completion of updating a router's RIB and the forwarding of
	an route update message (LSA for OSPF/LSP for ISIS) to a
	neighboring peer.

	Discussion:
	Protocol Convergence considers only the Control Plane.  IGP
	messaging is used to verify and measure convergence.  Updating
	of the FIB, hardware updating, rerouting of traffic, and packet
	loss are not considered.

	Measurement Units:
	LSA/LSP Transmitted or LSA/LSP Not Transmitted.
	N/A

	Issues:
	Protocol Convergence does not consider updating  of the FIB,
	hardware updating, rerouting of traffic, and resultant resulting packet
	loss.  Protocol Convergence is only a partial measurement of
	Route Convergence.

	See Also:
	Network Convergence
	Route Convergence
           	      IGP Data Plane Route Convergence

   3.3 Route Convergence

	Definition:
	The completion of the router's FIB becoming fully converged.

	Discussion:
	All
	Route Convergence is the action of all components of the router have been
	being updated with the most recent route change(s) including the
	RIB and FIB, along with software and hardware tables. Route
	Convergence can be observed externally by the rerouting of data traffic.
	Traffic to a new egress interface.

	Measurement Units:
	Converged or Not Converged
	N/A

	Issues:
	None

	See Also:
	Route Convergence Time
	Network Convergence
	Protocol Convergence
           	      IGP Data Plane Route
	Full Convergence
  	Convergence Event

   3.4  Full Route Convergence Time Event

	Definition:
	The amount of time it takes for Route Convergence to
	complete as measured by the time to drop from maximum
	forwarding rate and return to maximum forwarding rate
	after occurrence of a planned or unplanned action in the network event.
	that results in a change to an entry in the route table.

	Discussion:
	Convergence Events include link loss, routing protocol session
	loss, router failure, and better next-hop.

	Measurement Units:
	N/A

	Issues:
	None

	See Also:
	Convergence Packet Loss
	Convergence Event Instant

   3.5 Full Convergence

	Definition:
	Route Convergence Time for an entire route table.

	Discussion:
	When benchmarking convergence it is a metric applied useful to a single router.  Convergence Time could be calculated
	from packet loss.  However, this will give a better than
	actual result when converging many routes simultaneously. measure
	The preferred method time to obtain convergence an entire route table.  For example,
           	      IGP Data Plane Route Convergence Time is
	to measure

	A Convergence Event can produced for an OSPF table of 5000
routes so that the time to drop from maximum forwarding rate
	and return to maximum forwarding rate.

	Figure converge routes 1 shows a graph model of through 5000
is measured.

	Measurement Units:
	N/A

	Issues:
	None

	See Also:
	Network Convergence
	Protocol Convergence Time as measured
	from the data plane.  IGP
	Route Convergence Time is the
  	Convergence Event

   3.6 Convergence Packet Loss

	Definition:
	The amount of time for the Forwarding Rate to begin its downward
	slope upon occurrence of packet loss produced by a network event and then fully recover
	to the Maximum Forwarding Rate.  This is calculated as

	(eq 1)	Time(Convergence) = Time(Recovery) - Time(Network Event).

			Forwarding Rate versus Time

		   Time=Recovery    Time=Network Event	Time = 0sec
	Maximum		      ^		     ^		^
	Forwarding Rate--> ----\             /-----------
				\           /<----Route Convergence
	Route Convergence------->\	   / Event Slope
	Recovery Slope		  \_______/<------100% Packet Loss

	X-axis = Time
	Y-axis = Forwarding Rate

			Figure 1.
	until Route Convergence Graph occurs.

	Discussion:
	Packet loss can be observed as a reduction of forwarded
	traffic from the maximum forwarding rate.

	Measurement Units:
	seconds/milliseconds
	number of packets

	Issues:
	None

	See Also:
	Route Convergence
	Route
	Convergence Packet Loss
	Average Route Event
	Rate-Derived Convergence Time
	Loss-Derived Convergence Time

   3.7 Convergence Event Instant

	Definition:
	The time instant that a Convergence Event occurs.

	Discussion:
	Convergence Event Instant is observable from the data
	plane as the precise time that the device under test begins
	to exhibit packet loss.

	Measurement Units:
	hh:mm:ss:uuu
           	      IGP Data Plane Route Convergence

   3.5

	Issues:
	None

	See Also:
	Route Convergence
	Convergence Event
	Convergence Packet Loss
	Convergence Recovery Instant

   3.8 Convergence Recovery Instant

	Definition:
	The amount of packet loss until time instant that Route Convergence completes. occurs.

	Discussion:
	Route
	Convergence Packet Loss Recovery Instant is used to calculate observable from the
	Route Convergence Time.  Packet loss is an externally
	measurable metric. data
	plane as the precise time that the device under test no
longer exhibits packet loss.

	Measurement Units:
	number of packets
	hh:mm:ss:uuu

	Issues:
	None

	See Also:
	Route Convergence
	Full Route
	Convergence Packet Loss
	Convergence Event Instant

   3.9 Rate-Derived Convergence Time
	Route

	Definition:
	The amount of time for Convergence Packet Loss to
	persist upon occurrence of a Convergence Event Slope until
	occurrence of Route Convergence.

	Discussion:

	Rate-Derived Convergence Time can be measured as the time
	difference from the Convergence Event Instant to the
	Convergence Reovery Instant, as shown with Equation 1.

	(eq 1)	Rate-Derived Convergence Time =
		Convergence Recovery Slope

   3.6 Average Instant - Convergence Event Instant.

	Rate-Derived Convergence Time can be measured at the maximum
	forwarding rate.

Measurement Units:
	seconds/milliseconds
           	      IGP Data Plane Route Convergence

	Issues:
	None

	See Also:
	Route Convergence
	Convergence Packet Loss
	Loss-Derived Convergence Time

   3.10 Loss-Derived Convergence Time

	Definition:
	The amount of time it takes for Route Convergence to
	complete as calculated from the amount of packet loss
	and known forwarding rate.

	Discussion:
	Average Route Convergence Time is a metric applied to a
	single router.
	It can be calculated from packet loss that occurs due
	to a network event Convergence Event and subsequent Route
	Convergence. Convergence, as shown
	with Equation 2.

	(eq 2) Loss-Derived Convergence Time =
		Convergence Packets Loss / Forwarding Rate

		NOTE: Units for this measurement are
		packets / packets/second = seconds

	Measurement Units:
	seconds/milliseconds

	Issues:
	Use of Packet loss to calculate Route
	Loss-Derived Convergence Time will
	give time gives a better than
	actual result when converging many routes simultaneously.  Full Route Convergence Time is
	Because of this the preferred benchmark for IGP Route Convergence. reporting metric in most
Cases is Rate-Derived Convergence Time.

	See Also:
	Route Convergence
	Route
	Convergence Packet Loss
	Full Route
	Rate-Derived Convergence Time
	Route
	Convergence Event Slope
	Route Transition
	Convergence Recovery Slope
           	      IGP Data Plane Route Convergence

  3.7 Route Transition

   3.11 Convergence Event Slope Transition

	Definition:
	The characteristic of routers A router in which forwarding rate
	gradually reaches zero as output queues drain after a
	network event.

	Discussion:

           	      IGP Data Plane Route Convergence Event Slope is externally observable.
	Full Route

	Discussion:
	Rate-Derived Convergence Time ignores the Route Convergence Event Slope.  Average Route
	Transition.  Loss-Derived Convergence Time based upon the amount
	of packet loss takes the
	Route Convergence Event Slope Transition into
account.  The Convergence Event Transition is best observed for
Full Convergence.

	Measurement Units:
	seconds/milliseconds

	Issues:
	None

	See Also:
	Route Convergence
	Full Route

	Convergence Event
	Rate-Derived Convergence Time
	Average Route
	Loss-Derived Convergence Time
	Route
	Convergence Packet Loss
	Route
	Convergence Recovery Slope

   3.8 Route Transition

   3.12 Convergence Recovery Slope Transition

	Definition:
	The characteristic of routers a router in which forwarding rate
	gradually rises to the maximum value as many routes
	converge to recover from a network event.

	Discussion:
	Route Convergence Recovery Slope is externally observable.
	Full Route
	Rate-Derived Convergence Time ignores the Route
	Convergence Recovery Slope.  Average Route Transition.  Loss-Derived Convergence
	Time based upon the amount of packet loss takes the
	Route
Convergence Recovery Slope Transition into account.  The
Convergence Recovery Transition is best observed for Full
Convergence.

	Measurement Units:
	seconds/milliseconds

	Issues:
	None

	See Also:
	Route Convergence
	Full Route
	Rate-Derived Convergence Time
	Average Route
	Loss-Derived Convergence Time
	Route
	Convergence Packet Loss
	Route
	Convergence Event Slope Transition
           	      IGP Data Plane Route Convergence

   3.9  Reroute

   3.13  Route Convergence Time

	Definition:
	The amount of time it takes for Route Convergence to
	complete as observed from rerouting of traffic to a
	new egress interface.
	new egress interface due to a change in next-hop without
packet loss.

	Discussion:
	Reroute
	Route Convergence Time is the IGP Route Convergence
	benchmark to be used for network events that produce
	a change in next-hop without packet loss.  An example

	Measurement Units:
	seconds/milliseconds

	Issues:
	None

	See Also:
	Route Convergence
	Rate-Derived Convergence Time
	Loss-Derived Convergence Time

   3.14 Restoration Convergence Time

	Definition:
	The amount of this is time for the router under test to restore
	traffic to the original outbound port after recovery from
	a cost change Convergence Event.

	Discussion:
	Restoration Convergence Time is the amount of time to
	Converge back to the original outbound port.  This is achieved
	by recovering from the Convergence Event, such as restoring
	the failed link.  Restoration Convergence Time is measured
	using the Rate-Derived Convergence Time calculation technique,
	as provided in which an backup path becomes Equation 1.  It is possible, but not desired
	to have the preferred path. Restoration Convergence Time differ from the
	Rate-Derived Convergence Time.

	Measurement Units:
	seconds/milliseconds
	seconds or milliseconds

	Issues:
	None

	See Also:
	Convergence Event
	Rate-Derived Convegence Time
           	      IGP Data Plane Route Convergence

   3.15 Packet Sampling Interval

	Definition:
The rate at which the tester (test equipment) polls to make
measurements for arriving packet flows.

	Discussion:
	Metrics measured at the Packet Sampling Interval include
	packets received and Convergence Packet Loss.

	Measurement Units:
	seconds or milliseconds

	Issues:
	Packet Sampling Interval can influence the Convergence Graph.
	This is particularly true as Full Route Convergence Time
	Average Route less than 1 second
	is achieved.  The Convergence Time

   3.10 Event Transition and Convergence
	Recovery Transition can become exaggerated when the Packet
	Sampling Interval is too long.  This will produce a larger than
	actual Rate-Derived Convergence Time.  Guidelines for use of
	the Packet Sampling Interval are provided in [2].

	See Also:
	Convergence Packet Loss
	Convergence Event Transition
	Convergence Recovery Transition

   3.16 Local Interface

	Definition:
	An interface on the DUT.

	Discussion:
	None

	Measurement Units:
	N/A

	Issues:
	None

	See Also:
	Neighbor Interface
	Remote interface

   3.11

   3.17 Neighbor Interface
	Definition:
	The interface on the neighbor router or tester that is
	directly linked to the DUT's Local Interface.

	Discussion:
	None

	Measurement Units:
	N/A
           	      IGP Data Plane Route Convergence

	Measurement Units:
	N/A

	Issues:
	None

	See Also:
	Local Interface
	Remote interface

   3.12

   3.18 Remote Interface

	Definition:
	An interface on a neighboring router that is not directly
	linked to any interface on the DUT.

	Discussion:
	None

	Measurement Units:
	N/A

	Issues:
	None

	See Also:
	Local interface
	Neighbor Interface

   3.19 Preferred Egress Interface

	Definition:
	The outbound interface on DUT to the preferred next-hop.

	Discussion:
	Preferred Egress Interface is the egress interface prior to
	a Convergence Event

	Measurement Units:
	N/A

	Issues:
	None

	See Also:
	Next-Best Egress Interface
	Convergence Event
           	      IGP Data Plane Route Convergence

   3.20 Next-Best Egress Interface

	Definition:
	The outbound interface on DUT to the second-best next-hop.

	Discussion:
	Next-Best Egress Interface is the egress interface after to
	a Convergence Event

	Measurement Units:
	N/A

	Issues:
	None

	See Also:
	Preferred Egress Interface
	Convergence Event

   4. Security Considerations

        Documents of this type do not directly effect the security of
        the Internet or of corporate networks as long as benchmarking
        is not performed on devices or systems connected to operating
        networks.

   5. References

   [1]   Poretsky, S., "Benchmarking Applicability for IGP Data Plane
	 Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-app-00, draft-ietf-bmwg-igp-dataplane-conv-app-01,
	 work in progress, June October 2003.

   [2]   Poretsky, S., "Benchmarking Terminology Methodology for IGP Data Plane
	 Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-term-00, draft-ietf-bmwg-igp-dataplane-conv-meth-01,
	 work in progress, June October 2003.

   [3]   Callon, R., "Use of OSI IS-IS for Routing in TCP/IP and Dual
	 Environments", RFC 1195, December 1990.

   [4]   Moy, J., "OSPF Version 2", RFC 2328, IETF, April 1998.

           	      IGP Data Plane Route Convergence

  6. Author's Address

     	Scott Poretsky
        Avici Systems
        101 Billerica Avenue
        N. Billerica,
   	Quarry Technologies
  	8 New England Executive Park
   	Burlington, MA 01862 01803
    	USA
    	Phone: + 1 978 964 2287 781 395 5090
   	EMail: sporetsky@quarrytech.com
           	      IGP Data Plane Route Convergence

	Brent Imhoff
	WilTel Communications
	3180 Rider Trail South
	Bridgeton, MO 63045 USA
	Phone: +1 314 595 6853
	EMail: sporetsky@avici.com brent.imhoff@wcg.com

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