TWAMP
(Two Way Active Measurement Protocol)
Internet-Draft
Overview & Drill Down
for
PE784 707307b AGN+CORE-Predictive,
Proactive, Preventive Mnt -- WIPM Juniper
Probe
------------------ Session II --------------
5/21/2008
prepared by
TJ Wang
May 21, 2008
1
Recap of Session I
• TWAMP pronunciation
• Borrow OWAMP TCP well know port 861 for now; switch when
TWAMP ->RFC
• Unauthenticated mode + (vendor specific) ACL ~ current RTR/SAA
implementation
• Juniper, Cisco, AdTran, WWP are implementing TWAMP
• Request Session Command Number = 5
• Stop Sessions can only be issued by Session Sender (need improve
to prevent from hanging the Session Reflector forever)
• Overview of
– Connection Set Up (port, mode, accept, etc)
– Connection Commands (request session; start & stop sessionS)
– Test Packet Send and Receive Formats – did not have time for this -
• Today we Drill Down
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2
Logical Model
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3
Logical Model
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4
Connection Setup
•
•
•
•
Client->Server: TCP connection
Server->Client: Server Greeting
Client->Server: Set-Up-Response
Server->Client: Server-Start
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5
Connection Setup
Server Greeting
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6
Mode of Connection
• 1 for unauthenticated,
• 2 for authenticated, and
• 4 for encrypted.
• 0 means do not want connect
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7
Connection Setup
Set-Up-Response
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8
Connection Setup
Server-Start
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9
Values of Accept Field
•
•
•
•
0 OK.
1 Failure, reason unspecified (catch-all).
2 Internal error.
3 Some aspect of request is not
supported.
• 4 Cannot perform request due to
permanent resource limitations.
• 5 Cannot perform request due to
temporary resource limitations.
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TWAMP Control Commands
• Request-Session,
– Client->Server: Create-Session
– Server->Client: Accept-Session
• Start-Sessions,
– Client->Server: Start-Sessions
– Server->Client: Session-Ack
• Stop-Sessions
– Client->Server: Stop-Sessions or
– Server->Client: Stop-Sessions
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11
Create Test Sessions
Request-Session- part 1
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12
Create Test Sessions
Request-Session- part 2
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Create Test Sessions
Accept-Session
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Start-Sessions
Start-Sessions
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Start-Sessions
Session-Ack
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16
Unauthenticated Test Packet
Sequence numbers start with zero and are incremented by one
for each subsequent packet.
Note: TTL MUST = 255
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17
Timestamp
• The format of the timestamp is the same as in
[RFC1305] and is as follows: the first 32 bits
represent the unsigned integer number of
seconds elapsed since 0h on 1 January 1900;
the next 32 bits represent the fractional part of a
second that has elapsed since then.
• So, Timestamp is represented as follows:
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Unauthenticated Response Packet
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Stop-Sessions
Session-Sender Only
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
3
|
Accept
|
MBZ
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Number of Sessions
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
MBZ (8 octets)
|
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
|
HMAC (16 octets)
|
|
|
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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