I have a 2811 doing dNAT and not much else. I was playing around with NetFlow data exporting, when a very confusing issue arose.
Initially, both interfaces had ip route-cache flow configured, and everything worked fine. Then I switched to ip flow ingress, which AFAIK is the same command on newer IOS releases.
Now, if I turn inbound NetFlow off on LAN interface with no ip flow ingress, all DNS traffic from LAN to WAN stops coming through.
This is very confusing, since cisco command reference describe ip flow commands as commands for collecting data, not actually doing any switching, and ip route-cache flow is called deprecated and substituted by ip flow ingress.
I'd like to disable ingress netflow in favor of egress, but can't do that, since DNS service is of course mandatory. Even if that's not possible, I would very much like to know what's going on.
Any suggestions are greatly appreciated!
Current configuration : 2231 bytes
! Last configuration change at 00:19:29 UTC+4 Thu Aug 15 2013 by ***
So looks like CEF doesn't work right without ip flow ingress (route-cache flow) on LAN inteface. However, nowhere in the documentation was I able to find anything about CEF depending on inbound ip flow being enabled.
To sum up (all flow config shown for LAN interface):
That doesnt seem to be right. NetFlow needs CEF to be turn on, but CEF doesnt require NetFlow to be on. Does it only affect DNS traffic when you have CEF on and NetFlow off? What's the IOS version on the router?
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