[ntp:questions] ntp peer association in VLAN query

Danny Mayer mayer at ntp.isc.org
Tue Jan 20 01:02:42 UTC 2009


kiran shirol wrote:
> Danny,
> 
> NTP sends the response with same address as it came in. So are you 
> suspecting that the VLAN is causing this issue. What could possibly be going 
> wrong ?
> 

Then you need to show the exact send line and response line which is not
what you showed me. Run ntpd -D2 to see the sends and recvs.

Danny

> Just for my understanding, how does the peer association work in general ? 
> Any references would do.
> 
> Thanks
> Kiran Shirol
> 
> "Danny Mayer" <mayer at ntp.isc.org> wrote in message 
> news:4974A44F.4000004 at ntp.isc.org...
>> kiran shirol wrote:
>>> My switch has configured for peering with the following switches
>>>
>>> ntp peer 101.1.1.2
>>> ntp peer 101.2.2.2
>>> ntp peer 102.1.1.2
>>>
>>> Vlan has the following configuration:
>>> ip address 10.1.1.1/24
>>> ip address 20.1.1.1/24 secondary
>>>
>>> Peer sends the NTP message 20.1.1.2(Out-Interface) -> 20.1.1.1(VLANs 
>>> secondary IP)
>>> The response comes as 10.1.1.1(VLANs Primary IP) -> 20.1.1.2
>>>
>> That means that the VLAN is using the wrong address to reply to the
>> message. NTP will see that it does not match the going address and will
>> discard the message. That's correct behavior. You need to figure out why
>> the packet is coming back with the incorrect address. i suspect the VLAN
>> but I cannot be sure.
>>
>> Danny
>>
>>
>>> Traces:
>>> 2008-12-20 00:01:40.522776     20.1.1.2 -> 20.1.1.1     NTP NTP symmetric 
>>> active
>>> 2008-12-20 00:01:42.548166     10.1.1.1 -> 20.1.1.2     NTP NTP symmetric 
>>> passive 
> 
> 
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