Description

This article provides information on how to synchronize the time between the NTP server and NTP client, which are on different networks, via the routing-instance on EX-series switches. In this scenario, Switch 2 is acting as the NTP client, which is syncing time with the NTP server that is connected to switch 1.

Symptoms

alt

Scenario :
 
  • 10.130.35.0/24 is the network in the inet.0 primary routing-table.
  • 100.100.100.0/24 is the network in routing-instance, R1.

Solution

Configuration :

Switch 1 :

Switch 1 is configured to sync time with the NTP server at 10.130.35.159 .

NTP configuration :
set system ntp server 10.130.35.159 version 4
set system ntp server 10.130.35.159 prefer
set system ntp source-address 10.130.35.150
Defining the R1 Routing instance : 
set routing-instances R1 instance-type virtual-router
set routing-instances R1 interface ge-0/0/2.0
Defining the policy options :

The p1 policy is defined to accept routes from the R1 instance:
set policy-options policy-statement p1 from instance R1
set policy-options policy-statement p1 then accept
The p2 policy is defined to accept the 10.130.35.150/32 route from the primary instance: 
set policy-options policy-statement p2 from instance master
set policy-options policy-statement p2 from route-filter 10.130.35.150/32 exact
set policy-options policy-statement p2 then accept
Importing the R1 routing instance into the primary routing table :
set routing-options instance-import p1
Importing the 10.130.35.150/32 network from the primary routing table to the R1 routing-instance :
set routing-instances R1 routing-options instance-import p2
Switch2 :

NTP configuration : 
set system ntp server 10.130.35.150 prefer
Defining the route to 10.130.35.150 :
set routing-options static route 10.130.35.150/32 next-hop 100.100.100.2
The following command is issued to verify the NTP associations:

Switch 1 : 
user@switch> show ntp associations

remote                       refid         st t  when   poll   reach    delay    offset     jitter
==============================================================================
*10.130.35.159 80.80.83.32   2    - 38      16      377      1.102 11.298  18.420
Switch 2 : 
user@switch>show ntp associations
remote                       refid            st t    when   poll     reach       delay      offset    jitter
==============================================================================
*10.130.35.150 10.130.35.159 3      - 20       64       377          1.688    -0.611   2.147

Modification History

2021-03-25: Updated the article terminology to align with Juniper's Inclusion & Diversity initiatives.