[ntp:questions] ntp peer association in VLAN query

kiran shirol kiran.shirol at gmail.com
Mon Jan 19 17:09:50 UTC 2009


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 ?

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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