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.

• 在系统网络体系结构(sna)中,部分话路内的服务层,负责把操作管理数据(FMD)请求和响应邮送给特定网络可寻址单元(NAU)服务管理程序,并提供话路网络服务或话路表示服务,具体是哪种服务依话路类型而定。