UDP Port Allocation for the Receiver Port in Two-Way Active Measurement Protocol (TWAMP)
ZTE Corp.
gregimirsky@gmail.com
Ericsson
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Doddanekundi, Mahadevapura
Bangalore
Karnataka
560037
India
p.muthu.arul.mozhi@ericsson.com
Nokia
footer.foote@nokia.com
Telefonica
luismiguel.contrerasmurillo@telefonica.com
Verizon
luay.jalil@verizon.com
Transport
Network Working Group
Internet-Draft
IPPM
TWAMP
This document arguments and requests re-allocation of an UDP port number from the System Ports range
for a Reflector in Two-Way Active Measurement Protocol (TWAMP).
This document, if accepted, will be an update to the TWAMP Test protocol specified in RFC 5357.
One particular compelling vision of the Two-Way Active Measurement Protocol (TWAMP)
is widespread deployment of open servers that would make IP Performance Metrics (IPPM) measurements a commonplace.
This is complemented by the proliferation of the Internet of Things (IoT) devices, such as sensors, and the need for obtaining
IPPM measurements from those devices by the service provider. IoT devices are often constrained by limited processing power
and memory and benefit from TWAMP Light, as defined in Appendix I .
TWAMP Light provides a simple solution for devices to act as test points in the network, by avoiding the need for the TWAMP-Control
protocol . In the absence of TWAMP-Control, a registered (default) UDP port that can be used as the Receiver
Port for TWAMP-Test will simplify configuration and management of the TWAMP-Light test sessions.
This document requests re-allocation of the UDP port number from the System Ports range
as Receiver Port for TWAMP-Test.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
.
Section 3.5 describes in details the process of negotiating
value of the Receiver Port. The Control-Client, acting on behalf of the Session-Sender,
proposes the port number from the Dynamic Port range :
"The Receiver Port is the desired UDP port
to which TWAMP-Test packets will be sent by the Session-Sender (the
port where the Session-Reflector is asked to receive test packets).
The Receiver Port is also the UDP port from which TWAMP-Test packets
will be sent by the Session-Reflector (the Session-Reflector will use
the same UDP port to send and receive packets)."
But the proposed Receiver Port may be not available, e.g. being in use by other
test session or another application. In this case:
"... the Server at the Session-Reflector MAY suggest an alternate
and available port for this session in the Port field. The Session-
Sender either accepts the alternate port, or composes a new Session-
Request message with suitable parameters. Otherwise, the Server uses the Accept field to convey other forms of
session rejection or failure to the Control Client and MUST NOT suggest an alternate port;
in this case, the Port field MUST be set to zero."
The allocated TWAMP Receiver Port number
MAY be advertised by the Server.
The Control Client that supports use of the allocated
TWAMP Receiver Port MUST accept the port number advertised
by the Server. If the Server does not
support the allocated TWAMP Receiver Port, then it sends
another Session-Request message with new parameters.
Thus the deployment of the allocated TWAMP Receiver Port number is
backward compatible with existing TWAMP-Control solutions that are based on
. At the same time, use
of the UDP port number allocated from the User Port range
will help to avoid the situation when the Server
finds the proposed port being already in use.
TWAMP-Test may be used to measure IP performance metrics in an Equal
Cost Multipath (ECMP) environment. Though algorithms
to balance IP flows among available paths had not been standardized,
the most common is the Five-tuple that uses
destination IP address, source IP address, protocol type, destination
port number, and source port number. To attempt to
monitor different paths in ECMP network is sufficient to variate
only one of five parameters, e.g. the source port number. Thus,
there will be no negative impact on ability to have concurrent
TWAMP test sessions between the same test points to monitor
different paths in the ECMP network when using the allocated
UDP port number as the Receiver Port.
The allocation of the TWAMP Receiver Port from the User Port Range
benefits TWAMP Light mode
of the TWAMP-Test. The allocated UDP port number
may be used as default value for the Receiver Port to simplify configuration and
management of the TWAMP-Light test sessions.
The Service Name and Transport Protocol Port Number Registry defined in .
has been allocated UDP port 862
for TWAMP-Control protocol. IANA is requested to re-assign UDP port 862
as follows:
Service Name
Port Number
Transport Protocol
Description
Semantics Definition
Reference
twamp-test
862
UDP
TWAMP-Test Receiver Port
This document
The registered UDP port as the Receiver Port for TWAMP-Test may be used as
target of denial-of-service (DoS) or used by man-in-the-middle (MitM) attack.
To improve protection from the DoS following methods are recommended:
filtering access to the TWAMP Receiver Port by access list;
non-routable IPs outside of the domain for the TWAMP loopback.
MitM attack may try to modify the content of the TWAMP-Test packet thus altering
measurement results.
An implementation can use data consistency check to detect modification
of data. In addition, it can use encryption of TWAMP-Test packets to
prevent eavesdropping.