Ch. 5 Key Terms

Path through an internetwork through which packets are forwarded.

The IP address of the originating-host that is placed into the IP packet header.

Header defined by the IP.

Used to create IP packets by encapsulating data from higher layer protocols with an IP header.

Process:

1. router receives frame

2. discards data-link header & trailer

3. makes forwarding decision based on destination IP add.

4. adds new data-link header & trailer based on outgoing interface

5. forwards frame out the appropriate interface.

The passage of a data packet between two network nodes (for example, between two routers).

A network that is connected to a device's interface.

For example, networks that interface with the router are known to be directly connected.

Devices learn their initial IP routes based on being connected to these subnets.

Communication where the sender and receiver must prearrange for communications to occurs; otherwise, the communication fails.

Any communication in which the sender and receiver do not prearrange for communications to occur.

Layer 3 address to which the data is going.

Resources used to manage or operate the network.

• Consumes bandwidth
• Reduces the amount of data that can be transported across the network.

Network protocols or technologies that do not use the acknowledgment system to guarantee reliable delivery of information.

Networking layers that are not affected by the media being used.

In Ethernet these are all of the layers from the LLC sublayer of the Data Link layer and above.

Maximum Transmission Unit

Largest IP packet size allowed to be sent out a particular interface.

Ethernet defaults to 1500 because the data field is limited to 1500bytes [the IP packet sits within the Ethernet frames data field].

The dividing of IP datagrams to meet the MTU requirements of the Layer 2 protocol.

Time To Live

Field in the IP header that prevents a packet from indefinitely looping around an IP internetwork.

Routers decrease TTL field at each hop, once TTL=0 the packet is discarded.

Group of IP addresses that have the same value in the first part of the IP address.

For identifying a group by that part of the address.

IP addresses with the same subnet are typically on the same network medium - not separated by routers.

Short for subnetwork

A logical network composed of all the computers and networking devices that can be reached by sending a frame to the data link layer broadcast address.

Addressing scheme in which a network is partitioned into sections.

Each section identifier forming one part of each destination's address and the destination identifier forming another.

Group of 8 binary bits.

Used to divide IPv4 addresses into four components.

Device on a network that serves as an access point to other networks.

Is used by a host to forward IP packets that have destination addresses outside the local subnet.

List that a router holds in memory for the purpose of deciding how to forward packets.

Routing table entry that is used to direct frames for which a next hop is not explicitly listed in the routing table.

Is used to forward a packet when no other known route exists for a given packet's destination address.

Entry in an IP routing table that was created bc a network admin entered the routing config manually.

Routing that adjusts automatically to network topology or traffic changes.

Protocol used between routers so they can learn routes to add to their routing tables.