Cisco 3850-X PTP Support

[mike-hawley]

Problem Description

Expected behaviour:

PTP packets enter the first switch, transit through a gigabit trunk whilst it is also carrying ~600Mbps of large packet data, and exit the second switch in under 300us.

Detailed observed behaviour:

Intermittently, but only during heavy traffic, PTP packets arrive late, causing device clock skew.

This works fine on a Cisco 3750-X however, they are going end of sale in October and we will need to order the appropriate switch type through to 2017.  So I need the 3850-X to work in the same way as the 3750-X before this...;-(((

Regards - Mike

[Philip D'Ath]

What is PTP?

What software version are you running on the 3850?

[mike-hawley]

License Level: Ipbase
License Type: Permanent
Next reload license Level: Ipbase

cisco WS-C3850-48P (MIPS) processor with 4194304K bytes of physical memory.
Processor board ID FOC1908X0DT
3 Virtual Ethernet interfaces
52 Gigabit Ethernet interfaces
4 Ten Gigabit Ethernet interfaces
2048K bytes of non-volatile configuration memory.
4194304K bytes of physical memory.
250456K bytes of Crash Files at crashinfo:.
1609272K bytes of Flash at flash:.
0K bytes of Dummy USB Flash at usbflash0:.
0K bytes of at webui:.

Base Ethernet MAC Address : c8:00:84:d2:ce:80
Motherboard Assembly Number : 73-15800-07
Motherboard Serial Number : FOC190781QU
Model Revision Number : T0
Motherboard Revision Number : A0
Model Number : WS-C3850-48P
System Serial Number : FOC1908X0DT

Switch Ports Model SW Version SW Image Mode
------ ----- ----- ---------- ---------- ----
* 1 56 WS-C3850-48P 03.07.03.E cat3k_caa-universalk9 BUNDLE

Configuration register is 0x102

PTP = Precision Time Protocol

[Philip D'Ath]

What QoS markers are there on your PTP traffic?

Can you show the config of the first switch there the PTP device is plugged in, the two trunk links, and the exit port on the second switch?

[mike-hawley]

It is Auto QoS Trust DSCP.  I have logged a Cisco TAC case, and they are looking at it now.   I will update once they have been through it.

Thanks for taking the time to look.  If I get nowhere with TAC I will reach back out...;-)

[tyrell.warren]

Curious if you were ever able to resolve this? 

Running into a similar issue.

Thanks

[mike-hawley]

Yes, Cisco have released a new software release that has resolved this.

The latest is 16.3.2

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/16-3/release_notes/ol-16-3-3850.html

Regards - Mike