Setting up a high availability NTP system for our network on Cisco routers
Posted on 2015-02-10
I have a general idea of what I want to do, but I can't quite figure out how to do it. We have 5 Cisco routers that I would like to use as ntp servers for our network. Currently they are configured as 1 ST5 time server, getting its time from a public ST2 ntp server. The other 4 routers are configured at ST6 time servers, getting their time from the one getting its time from the Internet. The problem is that if the 1 router crashes that gets its time from the ST2 ntp source, we lose our authoritative time source.
I think what I'd like to do is set 2 or 3 of the routers to get their time from different ST2 ntp servers, then have all 5 set up as peers to "negotiate" a network time for our entire network (2 Windows domains & 1300+ linux workstations and servers at multiple locations).
The idea being we could have a complete failure of our Internet feed (we have 2 links with different carriers & BGP for failover), we could still have stable time services on the network.
I think what I want to do it set up "symmetric active mode" on 2 or 3 of the routers, getting their time from an authoritative external source,, then setting up peering on all 5. The rest of the network would get their time from all 5 routers.
Any help would be very much apprecaited.