topic RE: Configure NTP source ip in ExtremeSwitching (EXOS/Switch Engine)

Configure NTP source ip

ElCap — Thu, 09 Jul 2015 09:06:00 GMT

I am running EXOS 15.7.1 on an X670-G2 and im trying to configure NTP.
the ntp server is a few hops away and the connection from the switch to next router is using a point to point /30 vlan.
when it sends an ntp request it uses the source ip of the /30 point to point vlan, but i need it to use a different self ip.
is anyway to configure what ip to use to when sending ntp requests?

RE: Configure NTP source ip

Senguttuvan__Ar — Thu, 09 Jul 2015 11:47:00 GMT

Hi,

There isn't a feature to specify the source VLAN to carry the NTP request.

RE: Configure NTP source ip

ElCap — Thu, 09 Jul 2015 14:12:00 GMT

ok thanks for the info, ill have to work out a way around it.

RE: Configure NTP source ip

cbuchenau — Wed, 09 Dec 2015 16:01:00 GMT

Exactly my problem as well - is there a way to change the source ip-address, e.g. via ACL?

RE: Configure NTP source ip

ElCap — Wed, 09 Dec 2015 16:08:00 GMT

i didnt find a way... i ended up using the p2p ip and had to get the ntp server to allow it.

RE: Configure NTP source ip

cbuchenau — Wed, 09 Dec 2015 17:40:00 GMT

Thanks for your quick reply!

I can't do that: The provider is blocking traffic from that IP, as it's for BGP transit only.

Will let you know when (if) I have a solution...

RE: Configure NTP source ip

Matthew_Hum1 — Thu, 10 Dec 2015 15:44:00 GMT

Just a thought but could you set a static route in the routing table to force it out of a specific interface via next hop?

RE: Configure NTP source ip

cbuchenau — Thu, 10 Dec 2015 15:50:00 GMT

We are currently thinking of something similar. If I do just that, it will be redirected at the next hop back to original router and then routed again to next hop... so it has to be combined with an ACL as well, overwriting the static route in case it comes back.

RE: Configure NTP source ip

Matthew_Hum1 — Thu, 10 Dec 2015 15:52:00 GMT

...or static routes/PBR all along the path.

RE: Configure NTP source ip

Zakko — Fri, 18 Jan 2019 17:10:00 GMT

I have the similar situation.

I have a p2p / 30 net and mgmt network without NAT and several SVIs that are connected to the Internet(NAT). In this case, my NTP does not work, because the switch sends packets through these networks(/30 or mgmt) without NAT. Is there a simple way to configure the source IP for NTP after 3 years? (XOS 16.2.5.4 for G1 or XOS 21.1.5.2 for G2)