[ntp:questions] ntp peer association in VLAN query

Unruh unruh-spam at physics.ubc.ca
Mon Jan 19 17:23:19 UTC 2009


"kiran shirol" <kiran.shirol at gmail.com> writes:

>This is a multi-part message in MIME format.

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>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

That is a public IP address. YOu should NOT be using it on a private lan. 


>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=20

ntp will discard it of course. It only knows about messages by their ip
addrss. This is some different machine suddenly sending a random ntp
packet. It should be discarded. 


>Traces:=20
>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 passivePlease let me know if you need more =
>information.ThanksKiran Shirol"Danny Mayer" <mayer at ntp.isc.org> wrote in =
>message news:4974979F.6050903 at ntp.isc.org...> kiran shirol wrote:>> Hi =
>NTP experts,>> >> I am not able to establish ntp peer adjaceny with =
>secondary ip address on >> vlan interface.>> >> I noticed that when peer =
>sends a NTP message to Device Under Test's(DUT) >> vlan interface =
>secondary address, DUT would respond the message with source >> address =
>set to vlan interface's primary address instead of its secondary >> =
>address, and the peer has silently discarded such message from DUT.>> >> =
>Is this expected ? I am not able to understand why is the peer =
>discarding >> such a packet.>> >> Can someone explain the behavior of =
>NTP in VLANs. Any help I will be >> grateful.>> >> Thanks>> Kiran Shirol =
>> > Can you provide an example? It's hard to understand with words =
>though I> think I get your meaning. I may have an answer but I would =
>like to see> some IP addresses on what got sent what the vlan IP =
>addresses are and> how it was sent and what was received.> > Danny
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Yee, gads you have one mess of a netnews reader. Please throw it away and
get something useful In the above it has stripped the line feeds and then
it sends in html as well. 


>Content-Type: text/html;
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><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
><HTML><HEAD>

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