NTP on NX-OS reloaded!

Hi guys. It’s been quite a long time, but I have been pretty busy lately. I just wanted to drop a quick line to tell you that the NTP problem on NX-OS when using ACLs to filter NTP is gone after installing 6.2(2) on our Nexus 7010 with Sup2. Read the original article here.

But it does not work out of the box. Our config had to be adjusted with the following command.

ntp access-group match-all

So now the full working NTP config on the Nexus 7k is as follows. We use peering ACLs as well as serve-only ACLs to specify who is allowed to get time via NTP from our machines.

R1-l3# sh run ntp
ntp server key 1
ntp server key 1
ntp peer key 1
ntp peer key 1
ntp peer key 1
ntp source-interface loopback0
ntp authenticate
ntp authentication-key 1 md5 MY_SECRET_NTP_KEY
ntp trusted-key 1
ntp logging
ntp access-group match-all
ntp access-group peer 5
ntp access-group serve-only 6
ntp master 3

R1-l3# sh ip access-lists 5
IP access list 5
        10 permit ip any

        20 permit ip any

        30 permit ip any

        40 deny ip any any

R1-l3# sh ip access-lists 6
IP access list 6
        10 permit ip any

FHRP – a more detailed look at HSRP

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FHRP – Basic HSRP Configuration


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Dynamic Routing with RIP

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NTP problems on NX-OS

I recently encountered a weird problem concerning the ┬áNetwork Time Protocol on NX-OS on a Nexus 7k. I wanted to secure my NTP implementation with access-lists like I did all the time before on other platforms. Access-lists for peers and for clients … [Continue reading]

Static Routing on Cisco IOS

Basic Three Router Topology

Because this is gonna be a blog about a lot of routing & switching stuff what post could possibly be better to kick off this website than one that deals with routing? Well, it is gonna be about the easiest form of routing, namely static routing. … [Continue reading]

00101010 is born!

Hey networking people out there! This is the first post announcing the start of my new blog which will be concerned a lot with networking and security stuff mostly related to Cisco. I probably should have started this blog while pursuing my CCIE but … [Continue reading]