> Which is one of the reasons that we specified 1600 as the frame size > for most line disciplines, such as PPP over Frame Relay, etc., since > circa 1992.... > PPP itself is 1500, matching ethernet, in the vain hope that folks > would remember to distinguish "packet" data size from "frame" size. This problem is also one that plagues DSL, as many DSLAMs expect to see a full Ethernet packet, including Ethernet header, inside the frame/atm packet that comes in from the network. They strip the frame/atm header, and dump the contents onto the DSL/Ethernet wire. If you're using frame relay on the backhaul, a max-length Ethernet packet with both Ethernet and frame relay headers will obviously exceed the 1500-byte limit, and get truncated. If you pull the Ethernet header out, you need to get the DSLAM to generate a new one on the other side, which many of them verge on not being smart enough to do. -Bill