Saw this piece of hardware running at a Xilinx Seminar (X-Tech). Damn thing was running Quake! I'm guessing it was just the demo version. Looked pretty cool. Quake version?, I dunno, maybe 3 (sorry I'm not a big quake fan). It's too bad that it's so expensive (Almost as bad as Motorola CPU demo boards).
1) the 16-bit Identification value in the header is only used when the sender (the NAT box) MUST fragment the packet due to packet size restrictions on the route. The ID is used by the receiver to keep track of all incoming fragments. When it sees the MF flag as zero on the last fragment, it then assembles all fragments with common ID's. Fragmentation order is managed by the 13-bit fragment offset counter.
2) For all packets that come in under the MTU, the NAT box can safely change the ID to zero (unless the origonating OS is checking this value... I don't think it is.)
3) for packets that HAVE to be fragmented, just re-assign a random number as the ID.
Seems like a simple fix to me...
BTW, you can read RFC791 at;
http://www.faqs.org/rfcs/rfc791.html
- Eddy_D
Slashdot Mirror
I was all set to use this CPU in my new boy robot too! I was just figuring out how to make the rocket boots.... (Sh*t, I just dated myself)
Saw this piece of hardware running at a Xilinx Seminar (X-Tech). Damn thing was running Quake! I'm guessing it was just the demo version. Looked pretty cool. Quake version?, I dunno, maybe 3 (sorry I'm not a big quake fan). It's too bad that it's so expensive (Almost as bad as Motorola CPU demo boards).
1) the 16-bit Identification value in the header is only used when the sender (the NAT box) MUST fragment the packet due to packet size restrictions on the route. The ID is used by the receiver to keep track of all incoming fragments. When it sees the MF flag as zero on the last fragment, it then assembles all fragments with common ID's. Fragmentation order is managed by the 13-bit fragment offset counter. 2) For all packets that come in under the MTU, the NAT box can safely change the ID to zero (unless the origonating OS is checking this value... I don't think it is.) 3) for packets that HAVE to be fragmented, just re-assign a random number as the ID. Seems like a simple fix to me... BTW, you can read RFC791 at; http://www.faqs.org/rfcs/rfc791.html - Eddy_D