i think the point has been missed here, what is being asked is can you use the SFP-1GB-SX in the 10G wan ports, or do you have to use a SFP-10G-SR in those 2 ports? yes the MX250 can take SFP-1GB-SX but can they be used in tho 10G WAN interface on the MX250 rather than the normal ports ... View more