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Cisco 891 FW dropping TCP sessions

My Cisco 891 is randomly dropping tcp sessions which i believe is resulting in web page timeouts and half loads.

The error messages look like these. This example includes one local ip, but it happens to lots of internal hosts randomly

Aug 15 16:54:46.299: %FW-6-DROP_PKT: Dropping tcp session on zone-pair ccp-zp-in-out class ccp-insp-traffic due to Stray Segment with ip ident 0 

Aug 15 16:49:33.895: %FW-6-DROP_PKT: Dropping tcp session due to SYN inside current window with ip ident 0.

Aug 15 15:50:08.731: %FW-6-DROP_PKT: Dropping tcp session due to Stray Segment with ip ident 0


I've been googling the issue and no fixes have worked so far, nor am i really able to identify the source of this traffic. I've read it could be lots of out of order packets, so i enabled alarming by issuing parameter-map type ooo global -> alarming on. Nothing, nor is the out of order counter high. I've tried increasing the queue length and memory limit on virtual reassembly - no help.

I've checked my MTU, I can send 1500 fine. The interface is set to that. I went ahead and did an adjust-mss 1452 on the wan and vlan interfaces, still occuring.

I have checked my NAT timeout values, they are defaults.

I had a QoS service-policy set, which I took off thinking it may have been causing the drops. Still nothing.

My processor average usage is low.


What else can I check to identify the cause of these? My little 5MB line is definitely over saturated but this web page loading problem is only recent.

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