How to configure SNTP on Extreme Networks switches ?

Here is an express “how to” guide to configure SNTP on Extreme Networks switches (X440-G2 and X435 in my case).

SNTP service is used to synchronize time over network thanks to a protocol called NTP.

First thing first, if you have any firewall, please be sure to open following access for traffic from switches :

  • NTP request to 0.fr.pool.ntp.org (and 1.fr.pool.ntp.org)
  • DNS request to desired DNS server

Configure DNS

Before going further, you’ll need to configure DNS on your switches in order to resolve NTP server address :

switch# configure dns-client add name-server 1.1.1.1 vr VR-Default

Please note : bold elements in the previous can be changed as you wish and may differ according to your own configuration. You can also add a secondary DNS server.

Configure time zone

Then, you’ll need to configure time zone :

switch# configure timezone name UTC 120

Please note : bold elements can be changed. In my case, I’ve set it up for my own use with French time zone.

Description :

  • UTC means the name of the zone (standard) you can also use CET (which is 1 hour ahead UTC) or GMT…
  • 120 is the gap (in minutes) from the standard you’ve chosen (UTC +2h in that case, but in minutes…)

Configure SNTP client

Now, let’s configure SNTP client :

switch# configure sntp-client primary 0.fr.pool.ntp.org vr VR-Default

As previous commands : bold elements may vary for your own configuration.

Enable SNTP client

After this short configuration, you’ll need to enable SNTP configuration :

switch# enable sntp-client

Check you configuration

You can check the good configuration of SNTP client by using this command :

switch# show sntp-client 

SNTP client is enabled
SNTP time is valid
Primary server:fr.pool.ntp.org VR-Default
Secondary server:
Broadcasts: VR-Mamt
Query interval:64
Last valid SNTP update: From server:0.fr.pool.ntp.org, on Mon May 9 10:26:27 2022

SNTPC Statistics :
 Packets transmitted:
  to primary server:            18
  to secondary server:          0
 Packets received with valid time:
  from Primary server:          5
  from Secondary server:        0
  from Broadcast server:        0
 Packets received without valid time:
  from Primary server:          0
  from Secondary server:        0
  from Broadcast server:        0
 Replies not received to requests:
  from Primary server:          13
  from Secondary server:        0

In order to validate SNTP configuration, you’ll need to check following elements (in bold) :

  • SNTP client is enabled
  • SNTP time is valid
  • Primary server
  • Packets received with valid time

Please note that in my case, I got few packets categorized as “Replies not received to requests” which corresponds to a period where SNTP was trying to get response (beginning of sync).

You can also configure a “secondary server” with the following command :

switch# configure sntp-client secondary 1.fr.pool.ntp.org vr VR-Default

Recap

Here is a short recap (for admins who don’t have time) :

switch# configure dns-client add name-server 1.1.1.1 vr VR-Default
switch# configure timezone name UTC 120
switch# configure sntp-client primary 0.fr.pool.ntp.org vr VR-Default
switch# configure sntp-client secondary 1.fr.pool.ntp.org vr VR-Default
switch# enable sntp-client
switch# show sntp-client 

Final check

Finally, this command may return the correct date and time :

switch# show time

Hope you’ll enjoyed this brief article, thanks for reading !

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