One document matched: draft-hares-bgp-statemt-01.txt
Differences from draft-hares-bgp-statemt-00.txt
Internet Draft S. Hares
Document: draft-hares-bgp-statemt-01.txt NextHop
Technologies,
Inc.
Expires: December 2002 June 2002
BGP-4 Finite State Machine Table
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
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Abstract
This document describes the BGP-4 Finite State Machine in detail.
This Finite State machine (FSM) describes how the 27 events operate
on the 6 states described in the BGP-4 standard. These 27 events
include administrative events, timer events, TCP connectivity events
and BGP message events.
This document is standards track to accompany the BGP-4 [1] standard
as a standard document. This description augments the BGP-4 FSM
description (section 8 of BGP-4 draft).
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Table of Contents
Abstractààààààààààààààààààààààààààààààààààààààà.......1
1.0 BGP FSM Table Overviewàààààààààààààààààààààààààà..3
2.0 BGP FSM Tableààààààààààààààààààààààààààààààààààà..3
2.1 Part A - Administrative eventsàààààààààààààààààà..4
2.2 Part B - Timer eventsààààààààààààààààààààààààààà..5
2.3 Part C - TCP Eventsààààààààààààààààààààààààààààà..6
2.3.1 Transport Events.............................6
2.3.2 Sequences of TCP interchangesààààààààààààà...7
2.3.3 Flags to track TCP exchangeàààààààààààààààà..8
2.3.4 Processing based on Transport flags in
Connect and Active states....................8
2.4 Part D - BGP Message related eventsààààààààààààà..9
2.4.1 Collision Detect processing in Open Confirm..12
2.4.2 Collision Detect processing in Open Confirm..12
3.0 Actions in state table ààààààààààààààààààààààà.13
3.1 Actions for Initializationàààààààààààààààààààààà.13
3.2 Actions for Disconnectionààààààààààààààààààààààà.14
4.0 Security Considerationsàààààààààààààààààààààààà..17
5.0 Referencesàààààààààààààààààààààààààààààààààààààà.18
6.0 Author's Addressesàààààààààààààààààààààààààààààà.18
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1.0 BGP FSM Table Overview
The table below gives the BGP State machine in table format. There
are 6 states in the state table: Idle, Connect, Open Sent, Active,
Open Confirm, and Established. The states are listed as columns in
the table.
Each row of the table focuses on the state transitions when a single
event occurs. The event is listed as the row header
In each box of the table, the first entry in the box is the new
state. The second entry is the set of actions. Each action is
either specified (such as Ignore) or it given a Letter (such as B)
that is described at the end of the table.
For example, if an manual start event occurs in the Idle state, the
local system performs the actions listed under ôAö and goes to the
Connect state. The actions under the letter A are:
Action A
1) Initialize all BGP resources
2) ConnectRetryCnt set to 0
3) Start Connect retry timer with initial value
4) Initiate transport connection to BGP peer
5) Listen for connection set-up by remote BGP peer
If the bgp persistent peer oscillation protection is not enabled,
the following events will not occur in this state machine:
Event6: Automatic start with bgp flap stop on
Event8: Idle Hold timer expires
Symbols within the Table:
(opt) - Denotes an optional event which MAY be implemented
within a BGP implementation.
Collision Detect - Indicates the checks based on section 6.8 of
the bgp-4 draft which lists the rules for
detecting a collision of BGP connections.
After these rules have been followed, if this
connection is to be dumped then the "dumped"
function is followed". If this connection is
not to be dumped, then the Keep clause is
followed.
See peer damp - Indicates that the operations in this state
are covered in the BGP Peer Restart Backoff Mechanisms
[draft-ietf-hares-backoff-01.txt]
TP - Transport
TP IND - Transport Indication
TP REQ - Transport Connection Request
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TP REQ ACK - Transport Request Acknowledgement
Estab. - Establish state
Process based on - The exact processing of Transport messages in starting
TP flags(2.3.4) BGP connection are described in section 2.3.4.
2.0 BGP Finite State Machine
2.1 Part A - Administrative events
# Event Idle Connect Active Open Open Estab.
sent Confirm
-------------------------------------------------------------------
1 Manual Connect Connect Active/ Open Open Estab./
Start /A /Ignore Ignore Sent Confirm/ Ignore
/Ignore Ignore
-------------------------------------------------------------------
2 Manual Idle/ Idle/ Idle/ Idle/ Idle/ Idle/
Stop Ignore Z Z S S C
-------------------------------------------------------------------
3 Auto Connect/ Connect Active/ Open Open Estab./
start A /Ignore Ignore Sent / Confirm/ Ignore
(opt) Ignore Ignore
-------------------------------------------------------------------
4 Manual Active/ Connect/ Active/ Open Open Estab./
start & B Ignore Ignore Sent/ Confirm Ignore
passive Ignore /Ignore
(opt)
-------------------------------------------------------------------
5 Auto Active/ Connect Active Open Open Estab./
Start & B /Ignore /Ignore Sent/ Confirm/ Ignore
passive Ignore Ignore
(opt)
-------------------------------------------------------------------
6 Auto See peer Connect Active Open Open Estab.
start & damp /Ignore /Ignore Sent/ Confirm/ /Ignore
bgp flap draft/ Ignore Ignore
stop on F
(opt)
[note 1]
-------------------------------------------------------------------
7 Auto stop Idle/ Idle / Idle / Idle/ Idle/ Idle/
(opt) Ignore D D C C C
-------------------------------------------------------------------
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2.2 Part B - Timer events
# Event Idle Connect Active Open Open Estab
------------------------------------------------------------------- sent Confirm lished
8 Idle See bgp Idle / Idle / Idle / Idle / Idle /
Hold backoff D D E E E
timer draft
expires
(opt)
-------------------------------------------------------------------
9 Connect Idle/ Connect/ Connect/ Idle / Idle / Idle/
Retry V X F E E E
timer
expires
-------------------------------------------------------------------
10 Hold Idle/ Idle / Idle / Idle / Idle / Idle /
Timer V D D K K M
expires
-------------------------------------------------------------------
11 Keep- Idle / Idle / Idle / Idle / Open Establish
alive V D D E Confirm/ ed/
Timer Q Q
expires
-------------------------------------------------------------------
12 Delay Idle/ Open Open Idle/ Idle/ Idle /
BGP V Sent/ Sent/ E E E
Open H H
timer
(opt)
-------------------------------------------------------------------
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2.3 Part C - Transport (TP) events
2.3.1) Transport Events
# Event Idle CONNECT ACTIVE OPEN OPEN Estab.
Sent CONFIRM
-------------------------------------------------------------------
13 TP IND Idle/ Connect/ Active/ Open Open Estab./
and V Sent/ Confirm/
valid Process Process Track Track Track
peering based on based on 2nd 2nd 2nd
TP flags TP flags TP TP TP
flags flags session session session
(2.3.4) (2.3.4)
-------------------------------------------------------------------
14 TP IND Idle/ Connect/ Active/ Open Open Estab./
and V L L Sent/ confirm/ Ignore
invalid Ignore Ignore
peering
-------------------------------------------------------------------
15 TP Idle/ Process Process Open Open Estab.
REQ-ACK V based on based on Sent/ Confirm/ /
TP flags TP flags Track Track Track
(2.3.4) & Open 2nd TP 2nd TP 2nd TP
flags session session session
(2.3.4)
If TP If TP
connects: connects:
Open Sent Open
/H Sent / H
If TP If TP
connect connect &
timer delay timer delay
/ ZZ /ZZ
-------------------------------------------------------------------
16 TCP Idle/ Process Process Open Open Estab.
Connect V based on based on Sent/ Confirm /Ignore
Confirm TP flags TP flags Ignore /Ignore
(2.3.4) (2.3.4)
If Open If open
timer delay timer delay
/ZZ /ZZ
else: else:
OpenSent Open Sent
/H /H
-------------------------------------------------------------------
17 TP Idle/ Idle/ Idle / Active/ Idle / Idle /
Connect V D Y O Y T
FAILS
(RCV TCP FIN
or timeout)
-------------------------------------------------------------------
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2.3.2 Sequences of Transport
BGP can run over any Transport protocol. Examples of transport
protocols BGP can run over is TCP or STCP[6]. The BGP
FSM has the following transport events:
Event 13: Transport Connection Indication and valid source and
destination
Event 14: Transport Connection INdication and invalid source and
destination
Event 15: Transport Connection Acknowledgemen (Received)
Event 16: Transport Connection Confirmation (received)
Event 17: Transport Connection Failed
For TCP the following messages cause each sequence:
Event 13: TCP SYN received by local peer and valid source IP
address and Transport Port #, valid destination IP
address and Transport Port #.
Event 14: TCP SYN received by local peer with either invalid
source IP address or transport port # or invalid destination
IP address and Transport Port #.
Event 15: TCP SYN, ACK pair received by local peer from remote peer
Event 16: TCP ACK received from remote peer
Event 17: TCP FIN received from remote peer or an indication of Transport
Timeout
Each of these events is illustrated in the following 4 examples for
TCP.
1) Sequence 1: Local system initiates Transport connection
Received from Sent from
Remote BGP Peer Local BGP Peer
=============== ================
<----- Tranport Request
(within Action A or B)
[TCP: Syn]
Tranport
Connection ----->
Acknowledgement
(Event 15)
[TCP: SYN, ACK]
<---- Transport Confirmed
[TCP: ACK]
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2) Sequence 2: Remote system initiated Transport connection
Received from Sent from
Remote BGP Peer Local BGP peer
================ ================
Transport
connection
Indication ---->
(Event 13) <----- Tranport
[TCP: SYN] connection
Acknowledgement
(Action
[TCP: Syn, ACK]
Transport
Connection--->
Confirm [Event 16]
[For TCP: ACK]
3) Sequence 3: Competing Transport Requests
Received from Sent from
Remote BGP Peer Local BGP peer
================ ================
<----- Tranport Request
(within Action A or B)
[for TCP: Syn]
Tranport
Indication
& valid port ----->
(Event 14)
[for TCP: SYN] <------ Transport Connection Acknowledgement
[for TCP: Syn, Ack]
Transport
Confirm ------>
(Event 15)
[TCP: ACK]
4) Sequence 4: Rejected Transport connection
Received from Sent from
Remote BGP Peer Local BGP peer
================ ================
<----- Tranport Request
(within Action A or B)
[TCP: Syn]
Tranport
Connection ----->
Reject
(Event 17)
[TCP: FIN]
<---- Transport Rejection Confirmed
[TCP: FIN-ACK]
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5) Sequence 5: Failed Transport connection via timer
<----- Tranport Request
(within Action A or B)
[TCP: Syn]
[Timeout]
2.3.3 Flags to track Transport exchange
The list below is a list of flags for sub-state processing in
Connect and Active for the Transport. These substates may be
implemented as flags or sub-states
Tranport processing sub-states
================================
1) Await Transport Indication (Await TP IND)
2) sent Transport Connection Request (Sent TP REQ)
3) Await Transport Connection Confirmed (Await TCP CONF)
4) Null - set if no sub-state processing
Transport Flags relating to the BGP Open status in Active and Connect
Configuration:
1) Passive TCP connection - wait for other side to start TCP connection
2) Delay Open by timer - After establishing a TCP sessino, delay sending open
until timer expires
Status flag:
1) TCP connected
2.3.4 Processing based on Transport flags in Connect and Active state
This table has entries with 3 parts: State/ substate / action.
For example the entry:
Connect
/RCV TP
IND
/aa
has a transition to: Connect State, RCV TP IND substate, and action aa.
The sub-state processing is based on the sub-states of the
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| Connect sub-states
--------------------------------------------------
|#1 #2 #3 #4
|----------------------------------------
# Event |Await Sent Await null
|TP IND TP REQ TP CONF
|[TCP SYN] [TCP SYN] [TCP:ACK]
--------------------------------------------------
13 RCV |Connect Connect Connect Connect
TP IND|/Await /Await /Await /null
& valid|TP CONF TP CONF TP CONF
peering|/aa /ab /aa /ignore
--------------------------------------------------
15 RCV |Connect Connect Connect Connect
TP CONACK|/Sent /null /null /null
[TCP: |TP REQ
SYN,ACK]|/ab /ac /ac /ignore
---------------------------------------------------
16 Rcv |Connect Connect Connect Connect
TP |/Await /Sent /null /null
Connect|TP IND TP REQ
Confirm|/ignore /ab /ac /ac
---------------------------------------------------
| Active sub-states
--------------------------------------------------
|#1 #2 #3 #4
|----------------------------------------
# Event |Await Sent Await null
|TP IND TP REQ TP CONF
|[TCP SYN] [TCP SYN] [TCP:ACK]
--------------------------------------------------
13 RCV |Active Active Active Active
TP IND|/Await /Await /Await /null
& valid|TP CONF TP CONF TP CONF
peering|/aa /ab /aa /ignore
--------------------------------------------------
15 RCV |Active Active Active Active
TP CONACK|/Sent /null /null /null
[TCP: |TP REQ
SYN,ACK]|/ab /ac /ac /ignore
---------------------------------------------------
16 Rcv |Connect Connect Connect Connect
TP |/Await /Sent /null /null
Connect|TP IND TP REQ
Confirm|/ignore /ab /ac /ac
--------------------------------------------------
Action aa)
1) send TP Connect Acknowledge [TCP SYN, ACK]
Action ab)
1) send TP REQ [TCP SYN]
Action ac)
1) send TP Connection Confirmation [TCP ACK]
2) if bgp open delay flag set:
- clear connect retry timer
- set BGP delay timer
else:
- Set TCP Connected flag
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2.4 Part D - BGP Message related events
# Event Idle CONNECT ACTIVE OPEN OPEN Establish
Sent CONFIRM ed
-------------------------------------------------------------------
18 BGPOpen Idle/ Idle/ Idle/ Open Collision Collision
V D D Confirm/ Detect detect
N (6.8) (6.8)
See 2.4.1 See 2.4.2
below below
Discard: Discard:
R R
-------------------------------------------------------------------
19 BGP Open Idle/ Open Open Open Idle/ Idle/
& delay V Confirm/ Confirm/ Confirm/ E E
timer set H H H
-------------------------------------------------------------------
20 BGPHeader Idle/ Idle/ Idle / Idle/ Idle / Idle /
err V D D I I E
-------------------------------------------------------------------
21 OpenMsg Idle/ Idle/ Idle/ Idle/ Idle/ Idle /
Err V D D J J E
-------------------------------------------------------------------
22 Open Idle/ Idle/ Idle/ Idle/ Idle/ Idle /
collision V D D R R R
dump
existing
BGP
session
-------------------------------------------------------------------
23 Notify Idle/ Idle/ Idle/ Idle/ Idle/ Idle/
with V D D Y Y T
version
error
-------------------------------------------------------------------
24 Notifi- Idle/ Idle/ Idle/ Idle/ Idle/ Idle/
cation V D D Y Y T
Received
-------------------------------------------------------------------
25 Keepalive Idle/ Idle/ Idle/ Idle/ Estab Estab
message V D D E lished/ lished/
P P
-------------------------------------------------------------------
26 Update Idle/ Idle/ Idle/ Idle/ Idle/ Estab
message V D D E E lished/
W
-------------------------------------------------------------------
27 Update Idle/ Idle/ Idle/ Idle/ Idle/ Idle /
message V D D E E U
error
-------------------------------------------------------------------
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2.4.1 Collision Detect processing in Open Confirm
Upon receipt of an OPEN message, the local system must check for any
collision of BGP connections. Upon receiving an Open in Open Confirm
state, the local system checks against any existing
connections in the Open Confirm state, and connections in the Open
Sent state if it knows the BGP identifier by means outside the
protocol. The following rules from section 6.8 of [1] are followed:
1. The BGP identifier of the local system is compared to the
BGP Identifier of the remote system (as specified in the
Open message.)
2. If the value of the local BGP Identifier is less than the
remote one, the local system:
1) Sends an Open Message back to the remote peer
2) closes the BGP connection that already exists via
event 22 as a separate call to the state machine.
3) Stays in Open Confirmed state
3. Otherwise,the local system closes the newly created BGP session
by sending a TCP Fin on the new connection, and
stays in Open Confirmed state and execute Action R
2.4.2 Collision Detect Processing in Established state
Collection detection processing depends if the local system is
configured to process Open's in EStablished state. If the local system
is not configured to process Open's in the Established state,
the normal processing of Collision detect in Established state is to
have the local system close the newly created BGP session and stay
in Established state.
If the box has a configuration that indicates that the Collision
should be detected, the following tests will be made:
1. The BGP identifier of the local system is compared to the
BGP Identifier of the remote system (as specified in the
Open message.)
2.) If the value of the local BGP Identifier is less than the
remote one, the local system
1) Sends an Open statement back to the remote peer
2) Closes the BGP connection via event 22 as a separate
call to the state machine
3) transitions to the Open Confirmed state from
Established state
3.) Otherwise, the local system closes the new BGP connection
via action R
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3.0 Actions in state table
3.1 Actions for Initialization
Action A
1) Initialize all BGP resources
2) ConnectRetryCnt set to 0
3) Start Connect retry timer with initial value
4) Initiate transport connection to the BGP peer
(if using TCP, send a TCP
5) Listen for connection set-up by the remote BGP peer
(that is, listen for TCP syn, ack pair)
Action B
1) Initialize all BGP resources
2) ConnectRetryCnt set to 0
3) Start connect retry timer with initial value
4) Listen for connection set-up by remote BGP peer
[TCP syn]
3.2 Actions for Disconnection
Action C
1) Set Administrative stop in MIB code reason
2) Send Notification with Cease
3) Connect retry timer reset (set to zero)
4) If any routes are associated with BGP session, delete
these routes
5) Release all BGP resources
6) Drop TCP connection
(Send FIN, and await FIN-ACK)
7) Increment the ConnectRetryCnt by 1
8) BGP peer oscillation damping process [2]
Action D
1) Set FSM error in MIB reason code
2) Connect retry timer reset (set to zero)
3) If any routes are associated with the BGP session, delete
the routes associated with this BGP session.
4) Release all BGP resources
(including clear BGP Delay timer)
5) Drop TCP connection
[send TCP FIN and Await FIN-ACK)
6) Increment the connect retry count by 1
7) BGP peer oscillation damping process [2]
Action E
1) Set FSM error in MIB reason code
2) Send Notification with FSM error
3) Connect retry timer reset (set to zero)
4) If any routes are associated with the BGP session, delete
the routes associated with the BGP session
5) Release all BGP resources
6) Drop the TCP connection
[send TCP Fin and Await FIN-ACK]
7) Increment the ConnectRetryCnt by 1
8) BGP peer oscillation damping process [2]
Action I
1) Set BGP Header error in MIB reason code
2) Send Notification with BGP Header Error
3) Connect retry timer reset (set to zero)
4) Drop TCP connection
(Send a FIN, Await a FIN-ACK)
5) Release all BGP resources
6) Increment the ConnectRetryCnt by 1
7) BGP peer oscillation damping process [2]
Action J
1) Set Open message error in MIB reason code
2) Send Notification with Open message error
3) Connect retry timer reset (set to zero)
4) Release all BGP resources
5) Drop TCP connection
(Send a FIN, await a FIN-ACK)
6) Increment the ConnectRetryCnt by 1
7) BGP peer oscillation damping process [2]
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Action K
1) Set Hold Timer expired in MIB Reason code
2) Send Notification with Hold timer expired
3) Connect retry timer reset (set to zero)
4) Release all BGP resources
5) Drop TCP connection
(Send a Fin, await a FIN-ACK)
6) Increment the ConnectRetryCnt by 1
7) BGP peer oscillation damping process [2]
Action M
1) set Hold timer expired in MIB reason code
2) send Notification with Hold Timer expired
3) Delete Routes
4) Connect retry timer reset (set to zero)
5) Release all BGP resources
6) Drop TCP connection
(send a Fin, await a FIN-ACK)
7) Increment the ConnectRetryCnt by 1
8) BGP Peer oscillation damping process [2]
Action R
If Collision Detected (section 6.8) and this bgp session is
the sesion to be dumped,
1) set the Call Collision cease in MIB reason code
2) Send Notification with a Cease
3) reset Connect timer (set to zero)
4) Release all BGP resources
5) Drop TCP connection (Send TCP FIN, await TCP FIN ACK)
6) Increment ConnectRetryCnt by 1
7) BGP peer oscillation damping process [2]
Action S
1) Set Administrative down in MIB Reason code
2) Send Notificationwith Cease
3) Drop TCP connection [Send TCP FIN, await TCP FIN ACK)
4) set ConnectRetryCnt to 0
5) reset Connect retry timer (set to zero)
Action T
1) set appropriate code in MIB reason code
- either Notification, or TCP disconnect or
TCP failure
2) delete routes
3) Reset Connect retry timer (set to zero)
4) Release all BGP resources
5) Drop TCP connection
6) Incremetn the ConnectRetryCnt by 1
7) BGP Peer oscillation dampoing process [2]
Action U
1) Set Update error code in MIB Reason code
Action V
1) set FSM error in MIB reason code
Action X
1) set value of Notfication received in MIB reason code
2) Drop TCP connection (Send TCP FIN)
3) Restart Connection Retry Timer (with initial value)
4) Send TCP Sync
5) Listen for TCP Sync
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BGP-4 Finite State Machine June 2002
Action y
1) Set TCP disconnect in MIB reason code
2) Restart ConnectRetry timer (with initial value)
3) Release all BGP resources
4) Drop TCP connection (send FIN ACK)
5) Increment ConnectRetryCnt by 1
6) BGP peer oscillation damping process [2]
Action Z
1) Set Manual disconnect in MIB reason code
2) Drop TCP connection [Send FIN, await FIN Ack]
3) Release all BGP
4) Set ConnectRetryCnt to zero
5) Reset ConnectRetry timer
3.3 TCP Connection Actions
Action F
1) Restart ConnectRetry timer (with initial value)
2) Initiates a transport connection to the other bgp peer
[Send a TCP SYN]
3) Listen for remote transport connection that
may be initiated by the remote BGP peer (TCP connection)
Action G
1) Restart ConnectRetry timer (with initial value)
2) Listen for BGP peer connection
Action L
1) Reject TCP connection [send TCP FIN]
Action O
1) Clear BGP resources
2) Restart ConnectRetry Timer
3) Listen for TCP connection (Listen for TCP Sync)
Action ZZ:
1) Set the BGP Open delay timer to initial value
3.4) Sending the Open message
Action H
1) Clear ConnectRetry timer (clear to zero)
2) Complete BGP initialization
3) Clear BGP Open Delay timer
3) Send Open message
4) Hold timer set to Large value (4 minutes)
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BGP-4 Finite State Machine June 2002
3.5) Keepalive message related
Action N
1) Clear BGP delay timer
2) Reset BGP Connect Timer
3) Send KEEPALIVE message
4a) If negotiated Hold time value is non-zero,
- Set Keepalive timer
- Hold timer reset to negotiated Hold time value
[section 4.2 of bgp-4 draft [1]]
4b) If negotiated Hold time value is zero,
- Reset Keepalive timer
- Reset Hold timer
5) If value of Autonomous System field is the same
as the local Autonomous system number, set the
connection is an internal connection; otherwise it is
ôexternalö. (This impacts Update processing)
Action P
1) Restart Hold timer
Action Q
1) Send Keepalive message
2) Restart KEEPALIVE timer
3.6) Update packet related
Action W
1) Process update packet
2) Restart Hold timer
4.0 Security Considerations
Security concerns for BGP-4 are addressed in the BGP-4
specification, and accompanying specifications on TCP MD5 [3] and
IP Security[4]. No additional considerations need to be made for
the BGP-4 state machine description.
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6.0 References
[1] "A Border Gateway Protocol 4 (BGP-4)" Y. Rekhter, T. Li Editors
http://www.ietf.org/internet-drafts/draft-ietf-idr-bgp4-17.txt
[2] "BGP Peer Restart Backoff Mechanisms", S. Hares
draft-skh-bgp-backoff-00.txt
[3] "Protection of BGP Sessions via the TCP MD5 Signature Option"
A. Heffernan, rfc2385.txt
[4] Securing BGPv4 using Ipsec", D. Ward,
draft-ward-bgp-ipsec-00.txt
[5] TCP, RFC 793
[6] SCTP, RFC 2960
7.0 Author's Addresses
Susan Hares
NextHop Technologies, Inc
825 Victors Way Phone: 1-734-222-1610
Ann Arbor, MI USA Email: skh@nexthop.com
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