하루에 몇번정도 인터페이스가 재부팅되는 현상이 일어납니다. 전체 인터페이스는 아니고 몇개만 그렇습니다. log파일에 이런 메시지가 나옵니다. 무엇을 말하는건지 또 뭘 체크해야되는지 부탁드립니다.
*Dec  2 13:49:33: %LINK-3-UPDOWN: Interface Serial1/0/7, changed state to down
*Dec  2 13:49:34: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0/7, changed state to down
*Dec  2 13:54:15: %LINK-3-UPDOWN: Interface Serial1/0/7, changed state to up
*Dec  2 13:54:16: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0/7, changed state to up
*Dec  2 18:56:43: %LINK-3-UPDOWN: Interface Serial1/0/1, changed state to down
*Dec  2 18:56:44: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0/1, changed state to down
 --More--         *Dec  2 18:57:46: %LINK-3-UPDOWN: Interface Serial1/0/1, changed state to up
*Dec  2 18:57:47: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0/1, changed state to up
*Dec  3 00:06:43: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial4/2, changed state to down
*Dec  3 08:45:24: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial4/5, changed state to down
*Dec  3 08:45:34: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial4/5, changed state to up
*Dec  3 10:28:24: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial4/2, changed state to up
*Dec  4 12:42:51: %PARSER-3-BADSUBCMD: Unrecognized subcommand 0 in interface command 'media-type'
*Dec  4 12:42:51: %PARSER-3-BADSUBCMD: Unrecognized subcommand 0 in interface command 'media-type'
*Dec  4 13:00:51: %PARSER-3-BADSUBCMD: Unrecognized subcommand 0 in interface command 'media-type'
*Dec  4 13:00:51: %PARSER-3-BADSUBCMD: Unrecognized subcommand 0 in interface command 'media-type'

%PARSER-3-BADSUBCMD: Unrecognized subcommand 0 in interface command 'media-type'
이 메시지의 원인을 찾아야되는데 도움 부탁드립니다