The network layer provides services to the transport layer．It can be based on either (1)．In both cases，its main job is (2) packets from the source to the destination．

In network layer，subnets can easily become congested，increasing the delay and (3).

for packets．Network designers attempt to avoid congestion by proper design．Techniques include (4) policy，caching，flowcontrol，and more．

The next step beyond just dealing with congestion is to actually try to achieve a promised quality of service．The methods that can be used for this include buffering at the client，traffic shaping，resource (5)，and admission control．Approaches that have been designed for good quality of service include integrated services(including RSVP) ，differentiated services， and MPLS．(1)

A．virtual circuits or datagrams

B．TCP or UDP

C．TCP or IP

D．IP or ARP

[单选题]The network layer provides services to the transport layer．It call be based on either virtual circuits or datagrams．In both cases，its main job is（ ）packets from the source to the destination． A．dealing with B．sending C．routing D．receiving

[单选题]is a network layer device that supports multiple LAN interfaces and segments LANs into smaller collision and broadcast domains.A．RepeaterB．RouterC．BridgeD．Switch

[单选题]is a network layer device that supports multiple LAN interfaces and segments LANs into smaller collision and broadcast domains。A．RepeaterB．BridgeC．RouterD．Galway

[多选题]When the freight forwarder provides services on behalf of the consigneebasi

[多选题]When the freight forwarder provides services on behalf of the consignorbasi

[多选题]When the freight forwarder provides services on behalf of the consignorbasi

[判断题] NSAPI的全称为Network layer Service Access Point Identifier。（）A . 正确B . 错误

[判断题]A consolidator provides door-to-door and distribution services which are no

[多选题]When the freight forwarder provides services on behalf of theconsignor， he

[多选题]When the freight forwarder provides services on behalf of the exporter， he