Computer Networking Quiz 4, 5, 6

Packet loss can occur at router output ports and this loss can be prevented by increasing the switch fabric speed.

The 8-bit protocol field in the IP datagram contains information about which transport layer protocol (TCP or UDP) the destination host should pass the segment to.

Packet loss can be eliminated if the switching fabric speed is at least n times as fast as the input line speed, where n is the number of input ports.

A datagram with a private network address should be able to be present in the larger public Internet.

The main function of the control plane is forwarding, which is to determine the paths a packet takes from its source to its destination.

A link-layer switch forwards a packet based on the packet’s MAC (layer 2) address.

The main function of the data plane is packet routing, which is to route datagrams from their input links to their output links.

Forwarding is a router’s local action of transferring packets from its input interfaces to its output interfaces, and forwarding takes place at very short timescales (typically a few nanoseconds), and thus is typically implemented in hardware.

True or false: Link state algorithms: Computes the least-cost path between source and destination using complete, global knowledge about the network.

Routers use the AS-PATH attribute to detect and prevent looping advertisements; they also use it in choosing among multiple paths to the same prefix.

The NEXT-HOP attribute indicates the IP address of the first router along an advertised path (outside of the AS receiving the advertisement) to a given prefix. When configuring its forwarding table, a router uses the NEXT-HOP attribute.

Logically centralized control means that a logically central routing controller computes and distributes the forwarding tables to be used by each and every router, and each router does not compute its forwarding table, unlike the per-router control.

True or false: When an OSPF route sends its link state information, it is sent only to those nodes directly attached neighbors.

In the case of logically centralized control, the data plane and control plane are implemented in separate devices; the control plane is implemented in a central server or multiple servers, and the data plane is implemented in each router.

A distributed routing algorithm calculates the lease-cost path in an iterative, distributed manner by the routers. With a decentralized algorithm, no node has the complete information about the costs of all network links

If we using the analogy of cocktail party interactions, for polling protocol, there isn’t a discussion leader, but there is wine glass that the participants take turns holding. A participant is only allowed to talk if the participant is holding the wine glass.

With IP, datagrams in the same TCP connection can take different routes in the network, and therefore arrive out of order. TCP is still needed to provide the receiving end of the application the byte stream in the correct order.

If we using the analogy of cocktail party interactions, in Token Ring protocol, a discussion leader allows only one participant to talk at a time, with each participant getting a chance to talk in a round-robin fashion.

Although each link guarantees that an IP datagram sent over the link will be received at the other end of the link without errors, it is not guaranteed that IP datagrams will arrive at the ultimate destination in the proper order.