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NTP doesn't work on loopback interface on EXOS.

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TitleNTP doesn't work on loopback interface on EXOS.
Symptoms
If enable NTP only on loopback interface, switch can't synchronize time and date with NTP server:
* X670G2-48x-4q.81 # show configuration "ntp" 
#
# Module ntp configuration.
#
enable ntp
enable ntp vlan test-vlan
configure ntp server add 10.152.15.10 initial-burst
* X670G2-48x-4q.82 # 

* X670G2-48x-4q.82 # show vlan 
-----------------------------------------------------------------------------------------------
Name            VID  Protocol Addr       Flags                         Proto  Ports  Virtual   
                                                                              Active router
                                                                              /Total
-----------------------------------------------------------------------------------------------
Default         1    10.152.4.181   /26  -f----------T---------------  ANY    1 /63  VR-Default 
Mgmt            4095 ------------------------------------------------  ANY    0 /1   VR-Mgmt    
test-vlan       222  10.152.4.244   /26  -fL-------------------------  ANY    0 /0   VR-Default 
-----------------------------------------------------------------------------------------------
Flags : (f) IP Forwarding Enabled, (L) Loopback Enabled, (T) Member of STP Domain
Total number of VLAN(s) : 3 

* X670G2-48x-4q.83 # rtlookup 10.152.15.10
Ori  Destination        Gateway         Mtr  Flags         VLAN       Duration
#s   default            10.152.4.129    1    UG---S-um--f- Default    0d:0h:29m:54s
Origin(Ori): (s) Static, (#) Preferred unicast and multicast route.
Flags: (f) Provided to FIB, (G) Gateway, (m) Multicast, (S) Static,
       (u) Unicast, (U) Up
 
* X670G2-48x-4q.84 # ping 10.152.15.10 from 10.152.4.244
Ping(ICMP) 10.152.15.10: 4 packets, 8 data bytes, interval 1 second(s).
16 bytes from 10.152.15.10: icmp_seq=0 ttl=62 time=6.322 ms
16 bytes from 10.152.15.10: icmp_seq=1 ttl=62 time=2.135 ms
16 bytes from 10.152.15.10: icmp_seq=2 ttl=62 time=2.514 ms
16 bytes from 10.152.15.10: icmp_seq=3 ttl=62 time=2.134 ms
--- 10.152.15.10 ping statistics ---
4 packets transmitted, 4 packets received, 0% loss
round-trip min/avg/max = 2/3/6 ms

* X670G2-48x-4q.85 # show ntp association 10.152.15.10 statistics 
Remote Host         : 10.152.15.10                                      
Local Interface     : 0.0.0.0                                           
Time Last Received  : 319 seconds
Time Until Next Send: 9 seconds
Reachability Change : 319 seconds
Packets Sent        : 0
Packets Received    : 0
Bad Authentication  : 0
Bogus Origin        : 0
Duplicate           : 0
Bad Dispersion      : 0
Bad Reference Time  : 0
Candidate Order     : 0
 
* X670G2-48x-4q.86 # show ntp association
Remote                    Reference ID    St Poll Reach Delay   Offset   Disp  
========================= =============== == ==== ===== ======= ======== =======
!10.152.15.10            INIT            16 64   0     0.00000 +0.00000 3.99217
St(ratum)   : Distance from the reference clock
Disp(ersion): Maximum offset error of clock
Flags       : (!) Configured
* X670G2-48x-4q.86 #
Environment
  • EXOS
  • All EXOS platforms
  • NTP
Cause
NTP is not enabled on ingress and egress VLANs. On EXOS it is required that NTP is enabled on ingress and egress VLANs otherwise NTP packets will be dropped.
Resolution
Enable NTP on ingress and egress VLANs so switch can process NTP packets.
For the provided example following configuration should be added:
# enable ntp vlan Default


 
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