Description

This article describes a scenario when TWAMP server on a device running JUNOS doesn't reflect TWAMP test packets even if there were no issues with establishment of TWAMP control session.

Symptoms

TWAMP control session gets established successfully between TWAMP server in JUNOS and a TWAMP client, TWAMP client negotiates non-zero padding size for test packets. However, when TWAMP test is started, TWAMP test packets are not reflected by the TWAMP server.

Solution

Certain TWAMP clients fail to correctly generate TWAMP test packets if a non-zero padding was negotiated. As a result, when the test is started, they send TWAMP test packets with a padding size different from what had been negotiated with the TWAMP server. By default, JUNOS performs validation of padding size and drops TWAMP packets that fail validation. 

In 23.2R2-S3, 24.2R2 and newer JUNOS releases validation of TWAMP test packet padding size has been disabled by default in order to allow such TWAMP clients to interoperate with TWAMP server in JUNOS. 

Modification History
2024-12-12 : Minor formatting changes.


2024-08-01 : Article Created