If you need a primer on 'How to configure PTP' on Arista click here. If you understand Arista's implementation of PTP then wait no further and read the rest of the blogtorial on how to decode them from a RAW packet capture.
Key frames DATA is 46bytes and is broken down as follows. What is in bold is important for calculating UTC time of a given packet.
8Bytes - ASIC Ticks
8Bytes - UTC in ns
8Bytes - LAST SYNC
8Bytes - KEY TS
8Bytes - EGRESS Interface DROPS
2Bytes - User defined DEVICE ID
2Bytes - Egress interface of the keyframe
1Byte - FCS TYPE
1Byte - RESERVED
Showing posts with label PTP. Show all posts
Showing posts with label PTP. Show all posts
Sunday, October 18, 2015
Thursday, March 12, 2015
Precision Time Protocol PTP - Demystified
As Network Engineers we build highways (maybe Bundesautobahn where there are no speed limits) on top of which various protocols travel. As designers/architects, perhaps it would be beneficial for us to understand what is traveling on the highways we build.
I started to dip my feet into PTP and I realized there is more to PTP than meets the eye. I also realized that I knew very little about its operations so I decided instead of dipping my feet why not just dive right in -- head first. As any curious person would do, I started to read the RFCs and white papers. But before we get into PTP's operation, let's define a handful of key terms.
I started to dip my feet into PTP and I realized there is more to PTP than meets the eye. I also realized that I knew very little about its operations so I decided instead of dipping my feet why not just dive right in -- head first. As any curious person would do, I started to read the RFCs and white papers. But before we get into PTP's operation, let's define a handful of key terms.
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