Networking exam 4-6

Multiprotocol Label Switching (MPLS)

Is a wide area networking protocol that operates at both Layer 2 and 3 and does label switching.

subnet mask

In IPv4 addressing, a 32-bit number that, when combined with a device's IP address, indicates what kind of subnet the device belongs to.

VLAN tag

Part of an Ethernet frame which tells devices which VLAN that packet belongs to

NAT Traversal

Passing through network address translation (NAT) to reach a user. NAT hides private IP addresses from the public Internet; however, voice over IP (VoIP) and videoconferencing calls that originate from outside the network must locate the user's IP address. See STUN, UPnP and NAT.

Operational Data

Data that is produced by an organization's everyday operations. It's gathered in real time to provide a snapshot of what's happening in the present.

Forwarding refers to the network-wide process that determines the end-to-end paths that packets take from source to destination.

False

Link layer addresses are known as IP addresses.

False

NIC stands for network implementation carrier.

False

Per-router control is when a logically centralized controller computes and distributes forwarding tables to be used by each and every router.

False

SNMP stands for Standard Network Manipulation Protocol.

False

The network layer must determine the route or path taken by packets as they flow from a sender to a receiver. The algorithms that calculate these paths are referred to as control algorithms.

False

Dataplane

(sometimes known as the user plane, forwarding plane, carrier plane or bearer plane) is the part of a network that carries user traffic. The data plane, the control plane and the management plane are the three basic components of a telecommunications architecture.

token passing protocol

(taking-turns protocol) Doesn't have a master node, instead it "A small, special-purpose frame known as a token is exchanged among the nodes in some fixed order"

anycast address

A method of communications where a set of packets are sent to the first or closest computer within a set of computers.

routing loop

A routing process in which two routers discover different routes to the same location that include each other but never reach the endpoint.

guaranteed minimal bandwidth

As long as the sending host transmits bits (as part of packets) at a rate below the specified bit rate, then no packet is lost and each packet arrives within a pre-specified host-to-host delay

label switched router (LSR)

can be any intermediate router in the LSP between the ingress and egress routers. An LSR swaps the incoming label with the outgoing MPLS label and forwards the MPLS packets it receives to the next router in the MPLS path (LSP). An LSP can have 0 to 253 transit routers.

Control Plane Traditional Approach functions

destination based forwarding and generalized forwarding

interface

boundary between the host and physical link

time frame

the amount of time given to complete a document or project

external BGP connection (eBGP)

bgp connection that spans 2 ASs

BGP connection

bgp messages sent over a connection

Packet Scheduling

deciding which packet to send next on link

Non-blocking

asynchronous

fifo

first in first out

middleboxes

"any intermediary box performing functions apart from normal, standard functions of an IP router on the data path between a source host and destination host"

Random Access Protocols

- When a node has a packet to send, attempt to transmit the node at band rate. - No co-ordination among nodes - Nodes don't attempt to avoid collisions but try to recover from them -- collision detection -- collision correction

switching via memory

- traditional computers with switching under direct control of CPU - packet copied to system's memory - speed limited by the memory bandwidth (2 bus crossings per datagram)

Routing Processor

-Executes the routing protocols -Maintains routing tables and attached link state information -Computes the forwarding table for the router -Performs the network management functions

OpenFlow protocol

-operates between controller, switch -TCP used to exchange messages

repeater

A Physical layer device that amplifies the signals it receives on one port and resends it on another port. Used to extend the distance of a network segment.

Simple Network Management Protocol (SNMP)

A TCP/IP protocol that exchanges management information between networked devices. It allows network administrators to remotely monitor, manage, and configure devices on the network.

Forward Error Correction (FEC)

A mechanism for correcting data at the receiver that gets lost or corrupted during transport.

Autonomous System

A collection of IP networks and routers under the control of one administrative entity

ARP table

A database of records that maps MAC addresses to IP addresses. The ARP table is stored on a computer's hard disk where it is used by the ARP utility to supply the MAC addresses of network nodes, given their IP addresses.

plug and play device

A device that can be attached to or installed on a computer and then used.

Packet Scheduler

A function at the network protocol level that allocates bandwidth to competing online connections. Residing in the transmitting machine, it determines how many packets are handed to each connection (each flow) at a given time. A packet scheduler makes its determinations by observing the packet flows from the applications or by request from a quality of service (QoS) protocol such as RSVP or Diffserv. See QoS.

Cyclic Redundancy Check (CRC)

A mathematical algorithm that is executed on a data string by both the sender and the receiver of the data string. If the calculated CRC values match, the receiver can conclude that the data string was not corrupted during transmission.

point-to-point link

A link that consists of a single sender at one end of the link and a single receiver.

Load-Insensitive Algorithm

A link's cost does not explicitly reflect it's current (or recent past) level of congestion.

private network

A network whose access is restricted to only clients or machines with proper credentials.

BGP (Border Gateway Protocol)

A path-vector protocol used by ISPs to establish routing between one another.

Polling Protocol

A polling is conducted in which all the stations willing to send data participates. The polling algorithm chooses one of the stations to send the data. The chosen station sends the data to the destination. After the chosen station has sent the data, the cycle repeats.

Virtual Private Network (VPN)

A private data network that creates secure connections, or "tunnels," over regular Internet lines

NETCONF

A protocol defined by the IETF for installing, manipulating, and deleting the configuration of network devices.

border router

A router situated on the edge of an AS that connects the AS to one or more remote networks.

Successful Slot

A slot in which exactly one node transmits

Network Address Translation (NAT)

A technique that allows private IP addresses to be used on the public Internet.

Management Information Base (MIB)

A virtual database included in an SNMP-compliant device, containing information about configuration and state of the device that can be queried by the SNMP management station.

Slotted ALOHA

A wireless network communications protocol technique similar to the Ethernet protocol

SNMP (Simple Network Management Protocol)

An Application-layer protocol used to exchange information between network devices.

classful addressing

An IP addressing convention that adheres to network class distinctions, in which the first 8 bits of a Class A address, the first 16 bits of a Class B address, and the first 24 bits of a Class C address are used for network information.

Dijkstra's algorithm

An algorithm for finding the shortest paths between nodes in a weighted graph. For a given source node in the graph, the algorithm finds the shortest path between that node and every other. It can also be used for finding the shortest paths from a single node to a single destination node by stopping the algorithm once the shortest path to the destination node has been determined. Its time complexity is O(E + VlogV), where E is the number of edges and V is the number of vertices.

Binary Exponential Backoff

An algorithm that uses feedback to multiplicatively decrease the rate of some process(in this case slot time * 2^r where r is between 0, 1...(2^r -1)), in order to gradually find an acceptable rate.

Network Interface Card (NIC)

An expansion card that enables a computer to connect other computers or to a cable modem to facilitate a high-speed Internet connection.

Switching via a bus

An input port transfers a packet directly to the output port over a shared bus, without intervention by the routing processor.

Open Shortest Path First (OSPF)

An interior gateway routing protocol developed for IP networks based on the shortest path first or link-state algorithm.

Inter-autonomous system routing protocol

BGP

CSMA with Collision Detection

CSMA/CD: - carrier sensing, deferral as in CSMA - collisions detected within short time - colliding transmissions aborted, reducing channel wastage - used in wired LANs Collision detection: - easy in wired LANs + measure signal strengths, compare transmitted, received signals - difficult in wireless LANs + received signal strength overwhelmed by local transmission strength `

parity checks

Checks a byte of data Check is performed when data is received A parity bit is added (to the parity byte - as an 8th bit) Counts / checks number of 1's // Counts / checks to see if 1's are even/odd Can be even or odd If parity is incorrect, error is detected

VLAN Trunking Protocol (VTP)

Cisco proprietary protocol to automate the updating of multiple VLAN switches.

Centralized Routing Algorithm

Computes the least-cost path between source and destination using complete, global knowledge about the network.

Switching fabric

Connects the router's input ports to its output ports

DOCSIS is a link-layer protocol used by telephone companies to provide a digital subscribe line via a telephone line.

False

bit-level error detection and correction

Detecting and correcting the corruption of bits in a link-layer frame sent from one node to another physically connected neighboring node

DHCP steps

Discover, Offer, Request, Acknowledge

Channel Partitioning Protocols

Divide channel into smaller "pieces" (time slots)

configuration data

Enables a company to tailor a particular aspect of the system to the way it chooses to do business

An input port stores packets received from the switching fabric and transmits these packets on the outgoing link by performing the necessary link-layer and physical-layer functions.

False

BGP stands for Big Graph Protocol

False

CIDR stands for Classless Information Data Routing.

False

CSMA stands for collision slot mode available.

False

A broadcast link consists of a single sender at one end of the link and a single receiver at the other end of the link.

False

A link-state algorithm is iterative, asynchronous, and distributed

False

graph

G = (Nodes, Edges)

Broadcast Address

Generally, any address that represents all devices, and can be used to send one message to all devices. In Ethernet, the MAC address of all binary 1s, or FFFF.FFFF.FFFF in hex. For IPv4, see subnet broadcast address.

multiple access problem

How to coordinate the access of multiple sending and receiving nodes to a shared broadcast channel

Active Queue Management (AQM)

In Internet routers, active queue management (AQM) is the arbitrary reorder or drop of network packets inside the transmit buffer of a network interface controller. The task is performed by the network scheduler.

Internet Checksum

In checksumming techniques, the d bits of data are treated as a sequence of k-bit integers. One simple checksumming method is to simply sum these k-bit integers and use the resulting sum as the error-detection bits

DHCP request message

In response to the DHCP offer, the client replies with a DHCP request, broadcast to the server, requesting the offered address. A client can receive DHCP offers from multiple servers, but it will accept only one DHCP offer. Based on required server identification option in the request and broadcast messaging, servers are informed whose offer the client has accepted.[5]:Section 3.1, Item 3 When other DHCP servers receive this message, they withdraw any offers that they might have made to the client and return the offered address to the pool of available addresses.

switch table

Information used by a switch in switching decisions. At a minimum, contains rows that associate host addresses at Layer 2, with specific pairs on the switch

icmp

Internet Control Message Protocol. Used for diagnostics such as ping. Many DoS attacks use ICMP. It is common to block ICMP at firewalls and routers. If ping fails, but other connectivity to a server succeeds, it indicates that ICMP is blocked.

a link layer is variously called

LAN address, physical address, or a MAC address

Link-State Broadcast

Link State Update packets are OSPF packet type 4. These packets implement the flooding of link state advertisements. Each Link State Update packet carries a collection of link state advertisements one hop further from its origin. Several link-state advertisement may be included in a single packet. Link State Update packets are multicast on those physical networks that support multicast/broadcast. In order to make the flooding procedure reliable, flooded advertisements are acknowledged in Link State Acknowledgment packets. If retransmission of certain advertisements is necessary, the retransmitted advertisements are always carried by unicast Link State Update packets.

Load-Sensitive Algorithm

Link costs vary dynamically to reflect the current level of congestion in the underlying link.

Longest prefix matching rule

Longest prefix match (also called Maximum prefix length match) refers to an algorithm used by routers in Internet Protocol (IP) networking to select an entry from a routing table .[1] Because each entry in a routing table may specify a network, one destination address may match more than one routing table entry. The most specific of the matching table entries — the one with the highest subnet mask — is called the longest prefix match. It is called this because it is also the entry where the largest number of leading address bits of the destination address match those in the table entry. For example, consider this IPv4 routing table (CIDR notation is used): 192.168.20.16/28 192.168.0.0/16 When the address 192.168.20.19 needs to be looked up, both entries in the routing table "match". That is, both entries contain the looked up address. In this case, the longest prefix of the candidate routes is 192.168.20.16/28, since its subnet mask (/28) is higher than the other entry's mask (/16), making the route more specific. Routing tables often contain a default route, which has the shortest possible prefix match, to fall back on in case matches with all other entries fail.

Network Management

Management of systems on the network using various activities, methods, procedures, and tools that relate to the operation, administration, maintenance, and provisioning of these systems.

Network adapter

NIC

Input ports

Performs the physical layer function of terminating an incoming physical link at a router. It also performs link-layer functions needed to interoperate with the link layer at the other side of the incoming link. Perhaps most crucially, the lookup function is also performed at the input port; this will occur in the rightmost box of the input port.

Carrier Sense Multiple Access (CSMA)

Protocol used by EtherNet to listen for existing traffic and wait until the line is clear before sending data in order to avoid Collisions. (Layer 2)

Random Early Detection (RED)

Random early detection (RED), also known as random early discard or random early drop is an queueing discipline for a network scheduler suited for congestion avoidance.[1] In the conventional tail drop algorithm, a router or other network component buffers as many packets as it can, and simply drops the ones it cannot buffer. If buffers are constantly full, the network is congested. Tail drop distributes buffer space unfairly among traffic flows. Tail drop can also lead to TCP global synchronization as all TCP connections "hold back" simultaneously, and then step forward simultaneously. Networks become under-utilized and flooded by turns. RED addresses these issues.

Temporary IP Address

Refers to as a dynamic IP address, which is available for a specific amount of time for an Internet session.

dynamic routing algorithm

Routes change more quickly -Periodic update -In response to link cost changes

Static routing algorithm

Routes change very slowly over time, often as a result of human intervention.

DHCP offer message

Server to Client Message where each DHCP server broadcasts an available IP Address

SDN

Software Defined Network

NAT Translation Table

Special database in a NAT router that stores destination IP addresses and ephemeral source ports from outgoing packets and compares them against returning packets.

IP address lease time

Specifies the duration of a dynamically allocated IP address lease.

forwarding table

Table that maps destination address to a routers outbound links

hot potato routing

The AS gets rid of the packet (the hot potato) as quickly as possible (more precisely, as inexpensive as possible), by sending the packet to the gateway router that has the smallest router-to-gateway cost among all gateways with a path to the destination.

ip matching

The basic idea is to find consumers exposed to a campaign on a connected device by comparing the IP address when they were exposed to the ad against IP address when they come in to do a survey. When the IP addresses match, there is a high degree of probability that these are the same devices.

Collision Detection

The computational problem of detecting the intersection of two or more objects.

link-layer frame

The datagram from the network layer after the link-layer has attached another link header

DHCP discover message

The first time a DHCP client computer attempts to log on to the network, it requests IP address information from a DHCP server by broadcasting a DHCP Discover packet. The source IP address in the packet is 0.0.0.0 because the client does not yet have an IP address.

dotted-decimal notation (DDN)

The format used for IP version 4 addresses, in which four decimal values are used, separated by periods (dots).

Link layer switch

The least intelligent type of switch because it is nonprogrammable. Layer 2 switches are incapable of transmitting messages outside of the LAN.

aging time

The length of time a MAC address remains assigned to a port; length of time an IP address is assigned to a switchport

two-dimensional parity

The parity of both the column and the row containing the flipped bit will be in error.

carrier sensing

The process in which a network device first listens on the wire to see if any other device is currently transmitting.

Control Plane

The process of decision making, such as routing, blocking, and forwarding, that is performed by protocols.

address resolution protocol

The protocol that translates from IP address to MAC address.

Undetected bit errors

The receiver may be unaware that the received information contains bit errors.

Intra-autonomous System Routing Protocol

The routing algorithm running within an autonomous system

Channel propagation delay

The time it takes for a signal to propagate from one of the nodes to another.

Distance vector Algorithm

This class of routing algorithm builds a forwarding table using only information from its neighboring routers

in-order packet delivery

This service guarantees that packets arrive at the destination in the order that they were sent

guaranteed delivery

This service guarantees that the packet will eventually arrive at its destination

Guaranteed delivery with bounded delay

This service not only guarantees delivery of the packet, but delivery within a specified host-to-host delay bound (for example, within 100 msec).

Flow Table

This table matches incoming packets to a particular flow and specifies the functions that are to be performed on the packets. There may be multiple flow tables that operate in a pipeline fashion.

A middlebox is an intermediary box performing functions apart from normal, standard functions of an IP router on the data path between a source host and destination host.

True

ARP stands for address resolution protocol.

True

An autonomous system (AS) is a group of routers that are under the same administrative control.

True

DHCP stands for Dynamic Host Configuration Protocol.

True

For the most part, the link layer is implemented on a chip called the network adapter.

True

HOL stands for head-of-line blocking.

True

ICMP stands for Internet Control Message Protocol.

True

Link-state algorithms use global state information

True

Links are communication channels that connect adjacent nodes along the communication path.

True

OSPF stands for Open Shortest Path First.

True

Packet loss will occur when no memory is available to store arriving packets in a queue.

True

SDN stands for Software-Defined Networking

True

The SDN control plane is the network-wide logic that controls packet forwarding among the network's SDN-enabled devices.

True

The ability of the receiver to both detect and correct errors is known as forward error correction (FEC).

True

The boundary between the host and the physical link is called an interface.

True

The goal of a routing algorithm is to determine good paths from senders to receivers.

True

The multiple access problem deals with how to coordinate the access of multiple sending and receiving nodes to a shared broadcast channel.

True

switch are self learning

True

DHCP ACK message

When the DHCP server receives the DHCPREQUEST message from the client, the configuration process enters its final phase. The acknowledgement phase involves sending a DHCPACK packet to the client. This packet includes the lease duration and any other configuration information that the client might have requested. At this point, the IP configuration process is completed. The protocol expects the DHCP client to configure its network interface with the negotiated parameters. After the client obtains an IP address, the client may use the Address Resolution Protocol (ARP) to prevent address conflicts caused by overlapping address pools of DHCP servers.

Buffer Bloat

a cause of high latency and jitter in packet-switched networks caused by excess buffering of packets

HOL blocking

[Head-Of-Line Blocking] queued datagram at front of queue prevents others in queue from moving forward.

internal BGP connection (iBGP)

a bgp session between two router in the same AS

time slot

a bit of time

Virtual Local Area Network (VLAN)

a logical network that can separate physical devices without regard to the physical location of the device

multi-homed access ISP

a method of configuring one computer, called the host, with more than one network connection and IP address. The multi-homed method provides enhanced and reliable Internet connectivity without compromising efficient performance.

Tunneling

a process that encrypts each data packet to be sent and places each encrypted packet inside another packet

priority queuing

a routing feature in which frames in an interface output queue are prioritized based on various characteristics such as packet size and interface type.

Subnet

a subdivision of a network that is created either to conserve addresses or to support specific network requirements.

Command Line Interface

a user types commands represented by short keywords or abbreviations or presses special keys on the keyboard to enter data and instructions

Classes InterDomain Routing (CIDR)

a way to combine several class-C address ranges into a single network or route. This method of routing adds class-C Internet Protocol (IP) addresses. These addresses are given out by Internet Service Providers (ISPs) for use by their customers.

routing algorithm

algorithms to calculate routes or paths from sender to receiver

Link-State Algorithm

algorithms with global state information

Dynamic Host Configuration Protocol (DHCP)

allows dynamic IP address allocation so users do not have to have a preconfigured IP address to use the network

IP Anycast

an IP network addressing scheme that allows for multiple servers to share the same IP address

best-effort service

an Internet delivery service where the provider does not give any guarantees on when the data will be delivered or the quality of that data when it is delivered

link-state algorithms

an interior protocol used by every router to share the information or knowledge about the rest of the routers on the network. The link state routing algorithm is a distributed algorithm using which every router computes its routing table

broadcast link

can have multiple sending and receiving nodes all connected to the same, single, shared broadcast channel

internal router

connects only to hosts and routers within its own AS

network wide logic

controls how the datagram is routed among routers along an end-to-end path from the source host to the destination host

Top of Rack Switch

data center architecture design in which computing equipment like servers, appliances and other switches located within the same or adjacent rack are connected to an in-rack network switch.

network service model

defines the characteristics of end-to-end delivery of packets between sending and receiving hosts

Multiple Access Protocol

distributed algorithm that determines how nodes share channel, i.e., determine when node can transmit

Routing Policy

enables you to control (filter) which routes a routing protocol imports into the routing table and which routes a routing protocol exports from the routing table.

generalized forwarding

forward based on any set of header field values

important network layer functions

forwarding and routing

Datagram Format IPv6

expanded addressing capabilities, streamlined 40-byte header, flow labeling

Weighted Fair Queuing (WFQ)

generalized round robin each class gets weighted amount of service in each cycle

possible services network layer could provide

guaranteed delivery, guaranteed delivery with bounded delay, in-order packet delivery, guaranteed minimal bandwidth, security.

There is a piece of the network layer in each and every

host and router in the network

per-router functions

in the network layer, determines how a datagram arriving on one of a touter's input links is forwarded to one of that router's output links

the four router components

input ports, switching fabric, output ports, routing processor

forwarding and switching are often used

interchageably

gateway router

internal router

data plane

local, per-router function determines how datagram arriving on router input port is forwarded to router output port forwarding function

Control Plane: SDN Approach

logically centralized control

Packet Switch

makes forwarding decisions about where to send a packet next based on destination address.

forwarding

move packets from router's input to appropriate router output

datagram

network layer packet

Taking Turns Protocols

nodes take turns, but nodes with more to send can take longer turns

a crossbar switch is

non-blocking

Round Robin Queuing

one of the algorithms employed by process and network schedulers in computing. As the term is generally used, time slices (also known as time quanta) are assigned to each process in equal portions and in circular order, handling all processes without priority (also known as cyclic executive).

Switching via interconnection network

overcome bus bandwidth limitations banyan networks, crossbar, other interconnection nets initially developed to connect processors in multiprocessor advanced design: fragmenting datagram into fixed length cells, switch cells through the fabric. Cisco 12000: switches 60 Gbps through the interconnection network

we mostly use the term router in pace of

packet switch

Control Plane Traditional Approach

per-router control

packet loss

refers to data that never reaches its destination or gets discarded because it arrives too late

output ports

stores packets received from the switching fabric and transmits these packets on the outgoing link by performing the necessary link-layer and physical-layer functions

switching fabric accomplished by

switching via memory, bus and interconnection network

Decentralized Routing algorithm

the calculation of the least-cost path is carried out in an iterative, distributed manner. No node has complete information about the costs of all network links. Instead, each node begins with only the knowledge of the costs of its own directly attached links.

security

the network layer can encrypt all datagrams at the source and decrypt them at the destination, thereby providing confidentiality to all transport-layer segments

routing

the process of deciding which path to take on a network. This is determined by the type of network and the software used to transmit data.

traffic engineering using mpls

the process of selecting LS paths chosen by data traffic in order to balance the load on various links, routers, and switches in the network. This is most important in networks where multiple parallel or alternate paths are available.

filtering

the switch function that determines whether a frame should be forwarded to some interface or should just be dropped

non-preemptive priority queuing

the transmission of a packet is not interrupted once it has begun

primary role of the network layer

to move packets from a sending host to a receiving host

Destination-based forwarding

traditional forwarding where packets maybe forwarded to output ports based on their destination IP addresses; helps packer determine where to go next to reach path of final destination

Code Division Multiple Access (CDMA)

transmits multiple encoded messages over a wide frequency and then decodes them at the receiving end

Hierarchical architecture

uses multiple systems, with one system acting as a central server and the others working as clients

Datagram Format IPv4

version number, header length type of service, datagram length, identifier, flags, fragmentation offset, time to live, protocol, header sum check, source and ip destination addresses, options, and data

drop-tail policy

when the queue is filled to its maximum capacity, the newly arriving packets are dropped until the queue has enough room to accept incoming traffic. The name arises from the effect of the policy on incoming packets.

work-conserving queuing

will never allow the link to remain idle whenever there are packets queued for transmission