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For questions about the Network Time Protocol (NTP) on network devices, where this tag should only be used when configuring NTP on an on topic network device.

4
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1answer
48 views

Is it bad practice to use a Virtual Router for NTP-Clustering?

I'm trying to find information on whether it is possible to enable an NTP cluster containing multiple routers, that are configured with VRRP to share the same address. I am aware that with many ...
1
vote
1answer
31 views

Simple NTP question

Setting up NTP on a cisco 3560 so clients can be all on the same time. The switch it only used at layer 2. Outside of having a management VLAN for SSH, there isn't currently any config for anything ...
0
votes
1answer
112 views

NTP monitoring issue

I have set up a measurement in our monitoring tool to check the state of the NTP, the target is a Nexus 5596, i'm using the following oid : 1.3.6.1.4.1.9.9.168.1.1.11 But I'm getting : ...
2
votes
1answer
229 views

Cisco ACL for NTP

We have Cisco ACL configured for all inbound traffic and today i have add NTP to allow few remote NTP server to sync tim. I have created object-group NTP group and multiple remote NTP server in that ...
1
vote
1answer
89 views

How does Peer-to-Peer NTP resolve time variance?

If I have two servers set up with peer-to-peer NTP and both have different times, how do they decide what time to use?
4
votes
2answers
303 views

Cisco Switch - Why do I need to do time synchronization for them

I manage a mid-sized Industrial automation network. I have roughly 10 client machines and 4 server machines. Up until now, we didn’t have a GPS clock in the network. One of the machines, server-A, ...
0
votes
3answers
494 views

Endpoint is getting ARP response but not able to ping it/ connect it [closed]

I have a endpoint which is on vlan x and a SNTP server on vlan Y of same cisco switch. I am trying to synchronize my time from SNTP server. endpoint is able to resolve ARP and get the mac of SNTP ...
0
votes
2answers
247 views

Cisco IOS NTP server config causes slow boot

I tried to configure my router to use NTP server. I thought it is trivial but I was wrong. It causes a very nasty problem when router have yet to gain internet access (during boot). I see the ...
1
vote
1answer
5k views

Cisco NTP Clock is unsynchronized

I have two internap NTP server and i set them up on Cisco Router but this is what i am getting. R1#show ntp associations address ref clock st when poll reach delay offset ...
1
vote
2answers
3k views

NTP synchronization issue with Cisco ISE

We have a Cisco ISE 2.0 in our lab doing some 802.1X testing. To have synchonized times, we use an NTP server in the same subnet as the ISE to sync all the components (stratum 3, based on Bluecat ...
0
votes
1answer
132 views

Will a cisco Router relay NTP information to a Checkpoint firewall?

so i have a checkpoint firewall and a cisco router , cisco router clock os synchronized via a public NTP server, as we know, a route which a ntp client can also relay the ntp information, will it ...
4
votes
2answers
278 views

NTP architecture questions

I have a question about NTP. We want to setup our core switches as NTP master for our network. We have three data centers. Site A : Two Nexus as core Site B : two Nexus as core Site C : two 6800 (in ...
2
votes
1answer
488 views

IOS does not respond to NTP queries unless client is in “peer” ACL

I have set up NTP on a Cisco IOS device running IOS 15.2M, and this is my bare-bones config used for testing: ip access-list standard IPV4-ACL-NTP-PEER permit <UP.STREAM.NTP.SERVER> log ! ip ...
1
vote
3answers
159 views

How stable are clocks in network equipment

Most high end network equipment (switches and routers) can act as a NTP-server for hosts in the network, but I cant find any information on how stable these are. Does anyone have any information or ...
1
vote
1answer
1k views

Dell X1052 External NTP

I have a Dell X1052 network switch and I am trying to setup SNTP. I don't have a time server on my network and my SonicWall TZ400 doesn't seem to work as an NTP server. How do I get SNTP working to ...
2
votes
3answers
512 views

How to get local time from internet

I am programming for an embedded device and I want it to display the local time. I know I can get the UTC time by NTP or SNTP. However how can I convert it to the local time if I do not want the user ...
2
votes
2answers
75 views

Effects of local switch time on network performance

Given a collection of switches all communicating together, will the local time on the switching equipment configuration have any bearing on performance, or just a common reference point when ...
0
votes
2answers
1k views

Route NTP traffic through Routing-Instance

Switch 2 needs to route it's NTP requests through a specific vlan that is setup on a routing-instance. Current NTP setup on switch 2 is set system ntp server 10.0.0.21 set system ntp source-...
3
votes
1answer
535 views

NTP Authentication within a vrf

I have a Cisco ASR1002 WAN router with multiple vrfs per department. Each vrf has a loopback interface on the router, which can be used as an NTP server for remote devices in the respective vrf/...
2
votes
1answer
1k views

How are UDP source ports mapped on a NAT?

Here is an example use case; I am curious to see how this is suppose to work and why: Someone has a NAT router from their ISP. Behind the router are 2 PCs running Linux and using ntpd. ntpd sends ...
9
votes
2answers
1k views

Which QoS classification should be applied to NTP?

Cisco's Enterprise QoS Solution Reference Network Design suggests classifying NTP as network management traffic and marking it as CS2: When addressing the QoS needs of Network Management traffic, ...
3
votes
1answer
921 views

Time synchronization on cisco switches

I have LAN that must not be on Internet. I have a lot of switches. How to make core switch 4500 series to be some kind of NTP server, and all other switches to adjust their time with this core? Goal ...
3
votes
2answers
1k views

Access rule that permits NTP response

Nagios is used from HOST1 to check the NTP server on HOST2. One of the servers resides in an ACL. The assumption was that ip access-list extended vlanX permit udp host HOST1 X Y eq ntp deny ip ...
3
votes
1answer
4k views

Cisco Nexus 7k as NTP server

Anyone have experience with setting up their Nexus 7k core as an NTP server? I was thinking the code would look like below: ntp master stratum 2 ntp server ns.arc.nasa.gov prefer ntp server bitsy....
5
votes
2answers
2k views

Cisco NTP server does not respond to queries

I have an NTP configured through out our in a hierarchy. 100% reliable with regards to providing time for Cisco devices. At one of our sites we allow cameras, servers, and workstations to utilize our ...