We just replaced an older cisco switch 3600 and copied with a 9200 , using the same config as the existing one and left the MTU size on the new swithc at default of 1500. A number of hours later they started to have issues with the network and lost traffic to/from the site with OSPF erros. They had to change the MTU size to 9128 to correct the outage. When would you need such a large MTU size?
