in sna, the layer within a half session that routes fmd requests and responses to particular nau services manager components and that provides session network services or session presentation services, depending on the type of session 在系統(tǒng)網(wǎng)絡體系結構(sna)中,部分話路內的服務層,負責把操作管理數(shù)據(jù)(fmd)請求和響應郵送給特定網(wǎng)絡可尋址單元(nau)服務管理程序,并提供話路網(wǎng)絡服務或話路表示服務,具體是哪種服務依話路類型而定。