Traditional IP packet forwarding analyzes the （1）IP address contained in the network layer header of each packet as the packet travels from its source to its final destination. A router analyzes the destination IP address independently at each hop in the network. Dynamic （2） protocols or static configuration builds the database needed to analyze the destination IP address (the routing table). The process of implementing traditional IP routing also is called hop-by-hop destination-based（3） routing. Although successful, and obviously widely deployed, certain restrictions, which have been realized for some time, exist for this method of packet forwarding that diminish its （4）. New techniques are therefore required to address and expand the functionality of an IP-based network infrastructure. This first chapter concentrate on identifying these restrictions and presents a new architecture, known as multipleprotocol （5）switching, that provides solutions to some of these restrictions.

（1）是（）

A:datagram B:destination C:connection D:service

Traditional IP packet forwarding analyzes the____(1)____IP address contained in the network layer header of each packet as the packet travels from its source to its final destination．A router analyzes the destination IP address independently at each hop in the network．Dynamic ____(2)____protocols or static configuration builds the database needed to analyze the destination IP address(the routing table)．The process of implementing traditional IP routing also is called hop—by—hop destination—based____(3)____routing．Although successful，and obviously widely deployed，certain restrictions，which have been realized for some time，exist for this method of packet forwarding that diminish its____(4)____．New techniques are therefore required to address and expand the functionality of an IP—based network infrastructure．This first chapter concentrate on identifying these restrictions and presents a rew，architecture，known as multipIeprotocol____(5)____switching，that provides solutions to some of these restrictions．(1)

A:datagram B:destination C:connection D:service

Traditional network layer packet forwarding relies on the information provided by network layer （1） protocols, or static routing, to make an independent（2） decisions at each hop within thenetwork. The forwarding （3）is based solely on the destination （4） IP address. All packets for thesame destination follow the same path across the network if no other equal-cost paths exist.Whenever a router has two equal-cost （5）toward a destination, the packets toward the destinationmight take one or both of them, resulting in some degree of load sharing.

（3）是（）

A:connecting B:window C:decision D:destination

Traditional network layer packet forwarding relies on the information provided by network layer  (1) protocols, or static routing, to make an independent (2) decision at each hop within the network. The forwarding  (3) is based solely on the destination  (4) IP address. All packets for the same destination follow the same path across the network if no other equal-cost paths exist. Whenever a router has two equal-cost  (5) toward a destination, the packets toward the destination might take one or both of them, resulting in

空白（3）处应选择（）

A:connection B:window C:decision D:destination

Traditional network layer packet forwarding relies on the information provided by network layer（）protocols, or static routing, to make an independent （） decisions at each hop within the network. The forwarding （） is based solely on the destination（） IP address. All packets for the same destination follow the same path across the network if no other equal-cost paths exist. Whenever a router has two equal-cost （） toward a destination, the packets toward the destination might take one or both of them, resulting in some degree of load sharing.

The forwarding （） is based solely on the destination

A:connecting B:window C:decision D:destination

One ofthe main resposibilities ofICMP is to report  （） . Although technology hasproduced increasingly relaible transmission media, errors still exist and must be handled. IP isan  （）  protocol. This means that error checking and error control are not a concem ofIP. ICMP was designed, in part, to compensate for this shortcoming. Howerver, ICMP doesnot  （） errors, it simply report them. Error correction is left to the higher-levelpotocols. Error messages are always sent to the original  （）  because the only informationavailable in the datagram about the route is the source and destination IP addresses. ICMP usethe source IP address to sent the error massage to the source ofthe（）.

Error messages are always sent to the original（）because the only informationavailable in the datagram about the route is the source and destination IP addresses.

A:user B:destination C:source D:program

Traditional network layer packet forwarding relies on the information provided by network layer（）protocols, or static routing, to make an independent （） decisions at each hop within the network. The forwarding （） is based solely on the destination（） IP address. All packets for the same destination follow the same path across the network if no other equal-cost paths exist. Whenever a router has two equal-cost （） toward a destination, the packets toward the destination might take one or both of them, resulting in some degree of load sharing.

The forwarding （） is based solely on the destination

A:connecting B:window C:decision D:destination

One ofthe main resposibilities ofICMP is to report  （） . Although technology hasproduced increasingly relaible transmission media, errors still exist and must be handled. IP isan  （）  protocol. This means that error checking and error control are not a concem ofIP. ICMP was designed, in part, to compensate for this shortcoming. Howerver, ICMP doesnot  （） errors, it simply report them. Error correction is left to the higher-levelpotocols. Error messages are always sent to the original  （）  because the only informationavailable in the datagram about the route is the source and destination IP addresses. ICMP usethe source IP address to sent the error massage to the source ofthe（）.

Error messages are always sent to the original（）because the only informationavailable in the datagram about the route is the source and destination IP addresses.

A:user B:destination C:source D:program