TWAMP NOKIA. to give more information about Two way activeTWAMP Light, also called Simple Two-way Activation Monitoring Protocol (STAMP), is the test packet used
to gather IP link measurement delay. The link measurement request source is the session-sender.
TWAMP Light requires the explicit configuration of a reflector on the peer. For SR OS, TWAMP Light
reflectors are configured in the config>router>twamp-light> reflector context. The reflector is referred to
as the session-reflector, the responder to the request.
The session-sender and the session-reflector must agree on the UDP port used to identify TWAMP
Light test packets. The SR OS configuration of the session-sender (configured using the dest-udp-port
command) and session-reflector (configured using the udp-port command) must match.
The TWAMP Light test packet was first introduced to support the Network Time Protocol (NTP) encoding
of the timestamp in the packet. Updates since the initial standardization of TWAMP Light supports the use
of the truncated Precision Time Protocol (PTP) timestamp format. A bit in the TWAMP Light test packet
header is repurposed to indicate the timestamp format encoded by the session-sender and the sessionreflector.
This change leads to some interoperability considerations. The timestamp format should be
consistent with the session-sender and session-reflector behavior. The link measurement session-sender
can be configured to encode NTP (default) or PTP and set the ‟z-bit” in the Error Estimate field accordingly.
This bit indicates the timestamp format carried in the packet. If the session-reflector sets the ‟z-bit” in the
Error Estimate field to indicate the timestamp format of the reply, the link measurement session-sender
can perform the necessary conversion (format and epoch) to produce the correct results. However, if the
session-reflector only reflects the original ‟z-bit” it received from the session-sender and uses a different
timestamp format in the packet, the delay calculations are not reliable because of the misinterpretation of