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Router not forwarding traffic out interface it was received on

Andrew Bailey
Level 1
Level 1

Ok, here is my scenario, I have traffic coming from a firewall destined for the PC. The firewall, router and PC are all on the same /27 subnet, the switch is just L2. If my firewall has a static host route for the PC pointing to the Router, the traffic fails to reach the PC. I understand that I don't need this static route as the PC is on the firewall's connected subnet, but for other reasons I can't go into here, I had the route there.

What would prevent the router from receiving the traffic and forwarding it back out the interface it was received on and sending it to the PC? Even though the route is unneeded I am curious 


Static Route on firewall: PC ---> Router

Firewall ---- Switch----Router




4 Replies 4

Are you really sure that it's the router that doesn't forward the packet? It really should if there a re no filters set. How did you confirm this?

When I had streaming UDP video and when I pinged the PC from the firewall it didn't work, when I took the static route out I could ping and the video came through. I am pretty sure ping is allowed, but I don't manage the router. It really doesn't matter now, as this scenario is not longer in place. Thanks.

Bodrul islam
Level 1
Level 1

If I understand correctly, your ingress traffic is coming through your firewall > Router and then the PC? and your PC egress traffic is goint through your router > firewall?

Do you have a Pcap for this from your router to PC?

it will be easier to see where the traffic is being dropped.

What kind of firewall?

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