question about asynchronous mode and wic-1t

in CCNA & CCENT
Hi all,
I'm back for your suggestion ....still trying to solve my cisco router back to back connection.
i found the following info and I was wondering if it could be the answer to my two cisco 2620 router back to back connection problem!
"Cisco Wic-1T Module: When used in Cisco 1720 and 1600 Series Routers, the WIC-1T may also be operated in asynchronous mode. The WIC-1T is not supported in asynchronous mode when used in Cisco 2600 and 3600 Series Routers."
hey! how do i tell my two cisco 2620 router to communicate ONLY using synchronous mode.
is there any ios command ????????????
thanks
I'm back for your suggestion ....still trying to solve my cisco router back to back connection.
i found the following info and I was wondering if it could be the answer to my two cisco 2620 router back to back connection problem!
"Cisco Wic-1T Module: When used in Cisco 1720 and 1600 Series Routers, the WIC-1T may also be operated in asynchronous mode. The WIC-1T is not supported in asynchronous mode when used in Cisco 2600 and 3600 Series Routers."
hey! how do i tell my two cisco 2620 router to communicate ONLY using synchronous mode.
is there any ios command ????????????
thanks
Comments
conf-if#physical layer ?
Router(confi-if) physical layer ?