[44net] Re: [ARDC:44Net] IPIP Packet Corruption

All, I was trying to bring up an AMPRNet IPIP tunnel in my lab network, but when I did a packet capture on the WAN side of the gateway I am setting up, I noticed that on average, about 80% of the IPIP packets I receive from the UCSD gateway have their inner headers corrupted. As far as I can tell, the first 4 bytes of the inner header are being overwritten with a garbage byte sequence (hex 00-04-00-00). I have included a packet capture showing what's going on. At packet 63, the RIP announcement starts, and continues through packet 100, so there's some known-good traffic in there. Has anyone seen anything like this before? I have another AMPRNet IPIP tunnel set up on a datacenter server, and it has no such problem, so this is an isolated issue (i.e., not an issue with the UCSD gateway). The only other thing I could suspect is that the ISP-issued modem/gateway combo unit. Of course, I have no visibility into traffic upstream of this unit, so I don't have a way to know if it is causing the corruption. Unfortunately, my ISP doesn't let me disable the gateway function of the unit, so I have to suspect the firmware of this device. Any and all help is appreciated. I am going to call my ISP tomorrow and see if they are aware of any issues with these modem/gateway units. Thanks, Eric Johnson - AE0JE _._,_._,_ ------------------------------ Groups.io Links: You receive all messages sent to this group. View/Reply Online (#600) <https://ardc.groups.io/g/44net/message/600> | Reply to Group <44net@ardc.groups.io?subject=Re:%20%5BARDC%3A44Net%5D%20IPIP%20Packet%20Corruption> | Reply to Sender <micromashor@gmail.com?subject=Private:%20Re:%20%5BARDC%3A44Net%5D%20IPIP%20Packet%20Corruption> | Mute This Topic <https://groups.io/mt/110582298/5279349> | New Topic <https://ardc.groups.io/g/44net/post> Your Subscription <https://ardc.groups.io/g/44net/editsub/5279349> | Contact Group Owner &lt;44net+owner(a)ardc.groups.io&gt; | Unsubscribe <https://ardc.groups.io/g/44net/leave/12923996/5279349/682613783/xyzzy> [ micromashor(a)gmail.com] _._,_._,_