LAN Routing

NTP on HP Switch 5412Rzl2?

Occasional Visitor

NTP on HP Switch 5412Rzl2?

1) I have a local NTP server, 2 core switches and a bunch of access switches. NTP server is on vlan 50. I pointed one core switch to the local NTP server, it is working fine.

2) Management VLAN is, say, 70.

3) I want 1 more core switche to be peeromegle to the 1st core switch and the access switches to point to the 2 core switches and be stratum 4.

# 1 is working fine, how should i proceed with #3? I tried just pointing oxender ther switches to the core switch - they don't receive any info. Should i setup an ACL or would the exchange happen on the Management vlan? I don't see the appropriate "peer" commands on the switch either. Please advise.

Regular Advisor

Re: NTP on HP Switch 5412Rzl2?

Please check, its helpful or not

Step 1: Write the old config to memory
Start by issuing the command write memory before you do anything, that way you can boot the switch to recover your previous settings if you mess something up. If you're doing this over Telnet/SSH and the switch is miles away, you might wanna consider using the reload command as well to tell the switch to reboot after a couple of hours if you loose access to it, see link in the references section for my how-to on how this is done!

Step 2: Configuring General Time Settings
First, we need to configure stuff like time zone and DST (Day-Light Savings Time) rules.

Enter config mode by typing configure SW1# configure SW1(config)#

Now we'll set the DST rule:

Type time day and hit tab to autocomplete. Hit tab again to show you the available options.

SW1(config)# time daylight-time-rule none alaska continental-us-and-canada middle-europe-and-portugal southern-hemisphere western-europe user-defined

Write the beginning of the option you want, hit tab again, and hit enter. I'll use western-europe here in Finland.

SW1(config)# time daylight-time-rule western-europe

Then, we'll set the time zone with the following command:

SW1(config)# time timezone +120

This sets the normal (non-DST) time to GMT+2, so after timezone, type you GMT offset in minutes.

Step 3: Configuring SNTP Time Synchronisation
First, we'll set the timesync setting to sntp

SW1(config)# timesync sntp

That'll enable SNTP, so now that we've got that sorted, let's move on to configuring SNTP with the sntp command.

First, we'll set the SNTP mode to unicast:

SW1(config)# sntp unicast

Then we'll add the settings for which server to query for time.

I'll paste the console output here so you can see how it's done IRL, and remember that if you hit tab in the middle of a command the switch will give you tips or a list of options:

SW1(config)# sntp authentication Enable sntp Authentication broadcast Operate in broadcast mode <30-720> The amount of time between updates of the system clock via SNTP server Configure SNTP servers to poll time from. unicast Operate in unicast mode

SW1(config)# sntp server priority Priority of the Server Address.

SW1(config)# sntp server priority <1-3> Enter a number for the 'priority' command/parameter.

SW1(config)# sntp server priority 1 IP-ADDR SNTP server IPv4 address. IPV6-ADDR SNTP server IPv6 address.

SW1(config)# sntp server priority 1

That'll set the NTP server to priority 1 in the switch config, i.e. the server it will check time against first. You can add additional servers with priority 2 and 3 as backup servers.

Step 4: Check your settings
Check your settings so that they actually worked:

SW1(config)# show time Mon Nov 11 14:53:35 2013

SW1(config)# show sntp

SNTP Configuration

SNTP Authentication : Disabled Time Sync Mode: Sntp SNTP Mode : Unicast Poll Interval (sec) [720] : 720 Source IP Selection: Outgoing Interface

Priority SNTP Server Address Version Key-id

1 3 0


If the time is still wrong, you might wanna check your settings.

Step 5: Write the new config to memory
Remember to issue the command write memory to push your new settings to memory when you've verified that everything works.

A couple of tips; Some SNTP/NTP servers might require authentication, and you can set all that with the sntp command. SNTP is the same as NTP, except that it's missing a lot of the sync features of NTP (but since you don't need µsec accuracy on a switch, you'll be fine). NTP servers usually answers SNTP requests, so don't worry about that either. A little known fact is that most Microsoft Domain Controllers will actually answer SNTP requests, so try that if you don't have a separate NTP server in your network.

I Haq
Honored Contributor

Re: NTP on HP Switch 5412Rzl2?

Hi @DavidMalan with regard to your third request:

@DavidMalan wrote: 3) I want 1 more core switche to be peer to the 1st core switch and the access switches to point to the 2 core switches and be stratum 4

you should consider that the Aruba 5400R zl2 Switch series can't act as NTP Server for other peers, it can only act as an NTP Client using other NTP Servers as time sources. 

I'm not an HPE Employee
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