We have a Cisco 6509 IOS 12.2(17a)SX1 which has an interface (supervisor 720 card) which reports a large number of Giant Frame errors. We have tried setting the MTU size on the interface to 9126 but the Giant Frame errors persist at an alarming rate (1 in 10). Link is routed point to point link (ie not just switching over it) only doing ip traffic. There does not seem to be any noticeable impact on the network but I would like to find out what is causing the Giant Frames and how if at all we can stop them occurring. Any help/advice appreciated.