A collection of individual networks connected by intermediate networking devices that function as a single large network
An Internetwork
What are the 4 internetworking challenges?
Connectivity between disparate technologies
Reliable Service
Network Management (FCAPS)
Flexibility
What 2 devices are used to segment a network?
Routers and Switches
T/F: Switches and bridges are used to segment a network into collision domains
True
A router creates a _________ Domain
Broadcast
Definition of a Broadcast Domain
A portion of the network limited by its router connection to a specific group of host computers in a common LAN segment
Definition of a Collision Domain
A group of devices connected on the same physical media so that when two devices try to access the medium at the same time, the two signals collide and destroy the data stream
All hosts in a Broadcast Domain share what?
A subnet (A common logical network layer addressing scheme)
A formal set of rules and conventions that governs how computers and network entities exchange information over a network medium
Protocol
The world’s most popular open-system (nonproprietary) protocol suite
TCP/IP
What layer does TCP work at?
Transport Layer (Layer 4)
What layer does IP work at?
Network Layer (Layer 3)
What is the difference between virtual/logical addresses and physical addresses?
Virtual addresses are logical and unfixed, a physical address is unique to that interface
T/F: A router with 3 interfaces running 3 different protocols would require 9 network layer addresses
True, one address is needed for each protocol on an interface
_______ protocols build routing tables whereas _______ protocols encapsulate data to be sent over the network
Routing, Routed
_______ Protocols provide logical addressing that routers use to determine where to send the data packet on its way to the destination network
Routed
Routed Protocols operate at the upper/lower 5 layers of the OSI reference model?
Upper (Application, Presentation, Session, Transport, Network)
A Layer 3 protocol that contains addressing information and some control information that enables packets to be routed
Internet Protocol (IP)
What are the 2 primary responsibilities of IP?
(1) Provide connectionless, best-effort delivery of packets based on logically assigned addresses.
(2) provide fragmentation and reassembly of packets to support data links with different MTU sizes.
What part of IP breaks down packets to ensure they do not exceed the maximum message size of the network they are sent across?
Maximum Transfer Unit (MTU)
MTU has 2 flags, what are they?
“More packets to follow” and “Last fragment”
What protocol maps IP addresses to MAC addresses?
ARP. Address Resolution Protocol
What is the difference of ARP process on a single LAN vs. multiple LANs?
On a single LAN, only the host with the correct IP address replies to the ARP request and the originating host saves that MAC/IP combination.
For Multiple LANs, the local router checks its routing table to tell that the destination is on different LAN and acts as a proxy with its own MAC address for the sending host. This makes that router the Default Gateway
Protocol to enable network devices to learn the MAC and network layer addresses of other network devices
Hello Protocol
T/F: Hello messages are used as keep-alives to ensure the connected router is still functional?
True
What is a common use of ICMP?
Ping (Packet Internet Groper) requests
Ping is a ______ to _____ layer request
Network Layer (both blanks)
Network layer protocols responsible for path determination and packet switching
Routing Protocols
The 5 routing procols
RIP, IGRP, EIGRP, OSPF, BGP
What are the 5 Routed protocols mentioned?
IP, MTU, ARP, Hello, ICMP
What does an IP routing table contain, and what is it for?
Consists of destination address/next hop pairs, and is used to enable dynamic routing
Do routers monitor if packets make it to their destination?
No
What is a gateway
In this situation, it is a router that performs routing protocol functions between machines, networks within or between autonomous systems
A collection of networks under a common administration that share a common routing strategy
Autonomous system
These routers are used for information exchange within autonomous systems
Interior gateway routers (use IGPs)
These routers move information between autonomous systems
Exterior gateway routers (use EGPs)
An IP address on a layer 3 device that serves as an access point to or from a network
Default gateway (router port). It also can refer to a setting on a host, which points to the default gateway address
The act of moving information across a packet switching internetwork
Routing
What are the 2 basic activities routing?
Determining optimal paths
Transporting data packets through the network
What is the primary difference between routing and bridging/switching?
Routing occurs at Layer 3, bridging/switching occurs at Layer 2 (they use different information to accomplish their tasks)
What is the purpose of a router?
To connect one LAN segment to another LAN segment within a routing domain (Administrative Domain), and to connect to other remote areas outside the AD
T/F: Routers are capable of route analysis and path determination
True
What are the 2 major functions of routers?
Path determination
Packet switching
Determining the best, most cost-efficient paths from the available paths to the known destination network is known as what?
Path determination
Forwarding a packet on the way to a final destination based on MAC address of the “next hop router interface” is known as…
Packet switching
What are the 3 components of path determination?
- Routing metrics (measurements of the network)
- Routing algorithms (formula to calculate cost of paths, they initialize and maintain routing tables)
- Routing tables (results of algorithm, shows available paths and their costs)
Message that consists of sending a whole routing table to all directly connected routers
Broadcast (Routing Update Message)
Message sent between routers throughout the network to inform other routers of the state of the sender’s links
Multicast (Link State Advertisement)
Do routers use IP address or MAC address for getting to the “next hop”?
MAC address
What are some reasons for destruction of packets?
If the packet is at the router and the router does not have a listing for its destination, if an ACL deny criteria is met, if the packet version number is wrong, if the TTL counter expires, if the CRC check shows a bit error, if the DoD security bits are set and the computer isn’t authorized to receive, if the packet must be fragmented in order to send but the “allow fragmentation” flag is not set
