Packetloss on router whenever traffic increases

[olli.luotonen]

Hi, 

I have issue with my lab environment (diagram & router running config attached)

Whenever any of the clients in the behind NATted subnets generates traffic, latency increases dramatically and router start dropping packets. 

So far i have checked:

- interface duplex/speed settings

- cable

- nat translations on the router

- software bugs for software ran

The router itself is quite used so it can be faulty, but can i check the dropped packets on the chipset level somehow? Or do i have something misconfigured perhaps?

[Georg Pauwen]

Hello,

in inside to outside NAT, routing is checked first. According to your configuration, everything sent to 172.16.100.0/24 never gets natted, but sent to 172.16.0.4. Yet, you allow the entire 172.16.0.0/16 range in your NAT access list. Try and change your access list as below:

ip nat inside source list NAT interface GigabitEthernet0/0.1 overload
ip route 0.0.0.0 0.0.0.0 10.100.32.1
ip route 172.16.100.0 255.255.255.0 172.16.0.4
!
ip access-list standard NAT
permit 192.168.0.0 0.0.0.255
permit 172.16.0.0 0.0.0.255

This matches the IP address range of your inside interfaces...

[olli.luotonen]

OK, will check this!

[Julio E. Moisa]

Hi

I don't see anything wrong on your configuration, have you considered use a physical interface for the ip nat outside instead a sub interface?

[olli.luotonen]

Yes, and this was previously done without the sub-interfaces and only one internal range (172.16.0.0/24) but it still had the same issue.