Telecom Set

Front 1

What does MDN stand for?

Back 1

Mobile Directory Number

Front 2

What does MIN stand for?

Back 2

Mobile identification number (or MIN) refers to the 10-digit unique number that a Wireless carrier uses to identify a mobile phone. A MIN is a number that uniquely identifies a mobile working under Telecom Industry Association standards for cellular and PCS technologies. (e.g. EIA/TIA–553 analog, IS–136 TDMA, IS–95 or IS-2000 CDMA).

Front 3

What is the MSID?

Back 3

A mobile station ID (MSID) is a number that is associated with the home service provider and the wireless phone number. This is reprogrammed when the user changes home service providers. It can also be called the mobile identification number (MIN) and is not to be confused with the mobile device number (MDN) in the CDMA world, which is the device's telephone number.

Front 4

What is the Vision ID?

Back 4

[e-mail] == Slot#1 user name

Front 5

Describe the OSI layers

Back 5

1. Physical: Controls transmission of the bit stream over medium
2. Data Link Layer: Defines frames, provides flow control and error handling on the frame level
3. Network Layer: Establishes, maintains, and ends network connections. Defines how routing and relaying is handled.
4. Transport Layer: Provides flow control and error handling between two end points.
5. Session Layer: Manages user communication sessions.
6. Presentation Layer: Performs data transformation to present a common interface to applications. Functions such as reformatting, compression, encryption.
1. Application Layer: Variety of services, e.g. ensure privacy, authentication

Front 6

Describe DHCP Flows (starts discover and starts with request)

Back 6

alt: Starts from Discover
Client->Server 1: DHCP DISCOVER
Client->Server 2: DHCP DISCOVER
Server 1->Client: DHCP OFFER
Server 2->Client: DHCP OFFER
Client->Server 1: DHCP REQUEST
Server 1->Client: DHCP ACK
end

alt: Starts with Request
Client->Server 1: DHCP REQUEST \n(requests an IP that was used before)
Server 1->Client: DHCP NAK. \n Address not available
Client->Server 1: DHCP DISCOVER
Server 1->Client: DHCP OFFER
Client->Server 1: DHCP REQUEST
Client->Server 1: DHCP INFORM. \nClient may request more information from the server
Server 1->Client: DHCP ACK
end

Front 7

What are the players in the SIP protocol?

Back 7

Two user agents
Proxy Server
Registrar
Redirect Server

Front 8

Describe a typical SIP flow between two user agents.

Back 8

-INVITE()-}
{-100-Trying
{-180-Ringing
User picks up
{-200 OK
Hang up
-BYE()-}
<-200 OK

Front 9

What is SIP?

Back 9

Session Initiation Protocol is an IETF-defined signaling protocol widely used for controlling communication sessions such as voice and video calls over Internet Protocol (IP). The protocol can be used for creating, modifying and terminating two-party (unicast) or multiparty (multicast) sessions. Sessions may consist of one or several media streams.

The SIP protocol is an Application Layer protocol designed to be independent of the underlying Transport Layer; it can run on Transmission Control Protocol (TCP), User Datagram Protocol (UDP), or Stream Control Transmission Protocol (SCTP).

Front 10

What is SNMP?

Back 10

SNMP is an "Internet-standard protocol for managing devices on IP networks. Devices that typically support SNMP include routers, switches, servers, workstations, printers, modem racks. It is used mostly in network management systems to monitor network-attached devices for conditions that warrant administrative attention. SNMP is a component of the Internet Protocol Suite as defined by the Internet Engineering Task Force (IETF).

Front 11

How does SNMP work?

Back 11

Essentially, SNMP agents expose management data on the managed systems as variables. The protocol also permits active management tasks, such as modifying and applying a new configuration through remote modification of these variables. The variables accessible via SNMP are organized in hierarchies. These hierarchies, and other metadata (such as type and description of the variable), are described by Management Information Bases (MIBs).
An SNMP-managed network consists of three key components:
Managed device (implements SNMP, e.g. router)
Agent — software which runs on managed devices
Network management system (NMS) — software which runs on the manager


SNMP itself does not define which information (which variables) a managed system should offer. Rather, SNMP uses an extensible design, where the available information is defined by management information bases (MIBs). MIBs describe the structure of the management data of a device subsystem; they use a hierarchical namespace containing object identifiers (O

Front 12

What are the seven PDUs of the SNMP?

Back 12

GetRequest

A manager-to-agent request to retrieve the value of a variable or list of variables. A Response with current values is returned.

SetRequest

A manager-to-agent request to change the value of a variable or list of variables. A Response with (current) new values for the variables is returned.

GetNextRequest

A manager-to-agent request to discover available variables and their values. Returns a Response with variable binding for the lexicographically next variable in the MIB. The entire MIB of an agent can be walked by iterative application of GetNextRequest starting at OID 0.

GetBulkRequest

Optimized version of GetNextRequest. A manager-to-agent request for multiple iterations of GetNextRequest. Returns a Response with multiple variable bindings walked from the variable binding or bindings in the request. V2.

Response

Returns variable bindings and acknowledgement from agent to manager for GetRequest, SetRequest, GetNextRequest, GetBulkRequest and InformRequest. Error reporting is provided by

Front 13

What do you know about the SNMP protocol?

Back 13

SNMP operates in the Application Layer of the Internet Protocol Suite (Layer 7 of the OSI model). The SNMP agent receives requests on UDP port 161. The manager may send requests from any available source port to port 161 in the agent. The agent response will be sent back to the source port on the manager. The manager receives notifications (Traps and InformRequests) on port 162. The agent may generate notifications from any available port. When used with Transport Layer Security or Datagram Transport Layer Security requests are received on port 10161 and traps are sent to port 10162.[3].

SNMPv1 specifies five core protocol data units (PDUs). Two other PDUs, GetBulkRequest and InformRequest were added in SNMPv2 and carried over to SNMPv3.

All SNMP PDUs are constructed as follows:
IP header
UDP header
version
community
PDU-type
request-id
error-status
error-index
variable bindings

Front 14

What is peer-to-peer networking?

Back 14

Networking that can be used between two peer computers for sharing resources. One computer can act as a server. Build in to Win OS since Win 95.

Front 15

What's a protocol?

Back 15

A set of rules for communication between two or more parties.

Front 16

What is routing?

Back 16

When a computer needs to send a packet to a computer on another network.

Front 17

What is WEP and how does it work?

Back 17

Wireless Equivalent Privacy
WEP uses the stream cipher RC4 for confidentiality,and the CRC-32 checksum for integrity.

1. The client sends an authentication request to the Access Point.
2. The Access Point replies with a clear-text challenge.
3. The client encrypts the challenge-text using the configured WEP key, and sends it back in another authentication request.
4. The Access Point decrypts the response. If this matches the challenge-text the Access Point sends back a positive reply.

Front 18

What is PSK?

Back 18

Pre-shared key is an authentication method for 802.11 wireless networks.
A shared secret which was previously shared between the two parties using some secure channel before it is used.

The term PSK is used in WiFi encryption such as WEP or WPA, where both the wireless access points (AP) and all clients share the same key.

Each wireless network device encrypts the network traffic using a 256 bit key. This key may be entered either as a string of 64 hexadecimal digits, or as a passphrase of 8 to 63 printable ASCII characters.

Front 19

What is CHAP?

Back 19

In computing, the Challenge-Handshake Authentication Protocol (CHAP) authenticates a user or network host to an authenticating entity. That entity may be, for example, an Internet service provider. CHAP is specified in RFC 1994.

1. After the completion of the link establishment phase, the authenticator sends a "challenge" message to the peer.
2. The peer responds with a value calculated using a one-way hash function on the challenge and the secret combined.
3. The authenticator checks the response against its own calculation of the expected hash value. If the values match, the authenticator acknowledges the authentication; otherwise it should terminate the connection.
4. At random intervals the authenticator sends a new challenge to the peer and repeats steps 1 through 3.

Front 20

What is MSCHAPv2 and how does it work?

Back 20

MS-CHAP is the Microsoft version of the Challenge-handshake authentication protocol, CHAP. The protocol exists in two versions, MS-CHAPv1 (defined in RFC 2433) and MS-CHAPv2 (defined in RFC 2759).

1. Client requests a login challenge from the Server.
2. The Server sends back a 16-byte random challenge.
3a. The Client generates a random 16-byte number, called the "Peer Authenticator Challenge."
3b. The Client generates an 8-byte challenge by hashing the 16-byte challenge received in step (2), the 16-byte Peer Authenticator Challenge generated in step (3a), and the Client's username. (See Section 3 for details.)
3c. The Client creates a 24-byte reply, using the Windows NT hash function and the 8-byte challenge generated in step (3b). This process is identical to MS-CHAPv1.
3d. The Client sends the Server the results of steps (3a) and (3c).
4a. The Server uses the hashes of the Client's password, stored in a database, to decrypt the replies. If the decrypted blocks match the challenge, the Client is authentic

Front 21

What is EAP?

Back 21

EAP is an authentication framework, not a specific authentication mechanism. It provides some common functions and negotiation of authentication methods called EAP methods. There are currently about 40 different methods defined. (e.g. EAP SIM, PEAP).

Eap message types:
Request
Response
Success
Failure

Front 22

What is EAP-TLS and how does it work?

Back 22

Most secure EAP protocol that uses PKI with client-side and server-side certificates.

-}802.11 association
{-Identity Request
-}Identity Response (device id @ realm)
{-Request TLS-Start
-}Response: Client hello
{-Request: Server Hello, certificate, certificate request, ServerKeyExchange
-}Response: Client cert, server cert valid, cipherchange, TLS done
{-Request: Change cipherspec. TLS finished.
-}Response: EAP-TLS
{-EAP-Success

Front 23

What is EAP-TTLS?

Back 23

he client can but does not have to be authenticated via a CA-signed PKI certificate to the server. This greatly simplifies the setup procedure as a certificate does not need to be installed on every client.

-}802.11 association
{-Identity Request
-}Identity Response (device id @ realm)
{-Request TLS-Start
-}Response: Client hello
{-Request: Server Hello, certificate, certificate request, ServerKeyExchange
-}Response: ClientKeyExchange, cipherchange, TLS done
{-Request: Change cipherspec. TLS finished.
-}Response: EAP-TLS
{-EAP-Success

Front 24

Tell me about Ethernet.

Back 24

A computer networking technology for local area networks (LANs) commercially introduced in 1980. Standardized in IEEE 802.3,

Systems communicating over Ethernet divide a stream of data into individual packets called frames. Each frame contains source and destination addresses and error-checking data so that damaged data can be detected and re-transmitted.

Packet Format:
Preamble
Destination MAC address
Source MAC address
Type/Length
User Data
Frame Check Sequence (FCS)

Types: Standard (10Mbps), Fast (100Mbps), Gigabit (1000Mbps)

Front 25

Tell me about TCP.

Back 25

Stands for Transmission Control Protocol.
Created around 1970 by Department of Defense.

TCP provides reliable, ordered delivery of a stream of bytes from a program on one computer to another program on another computer.

The TCP header includes source PORT, destination PORT, sequence number, data size, and checksum.

Front 26

What does 10Base5 mean?

Back 26

10 is the network speed for Ethernet (10Mbps)
Base is the transmission type, e.g. Baseband
5 is the cable type. For coax, the length of the cable is used. 5== 500 meters.

Front 27

Name the 3 classes for private networks and the decimals they start with

Back 27

Class A: 10.0.x.x.x, 16,777,216 addresses
Class B: 172.16.xx, 1,048,576
Class C: 192.168...., 65,536 addresses

Front 28

What information is in the IP Packet?

Back 28

Version, Header Length, Total Length, Source IP, Target IP, Options, Time To Live, Header checksum

Front 29

What are ESNs?

Back 29

Electronic serial numbers (ESNs) were created by the U.S. Federal Communications Commission (FCC) to uniquely identify mobile devices.

ESNs are mainly used with CDMA phones (and were previously used by AMPS and TDMA phones), compared to International Mobile Equipment Identity (IMEI) numbers used by all GSM phones.

ESNs are 32 bit, first 14 are manufacturer codes, last 18 are for devices.

Front 30

What is a Hub?

Back 30

An Ethernet hub, active hub, network hub, repeater hub or hub is a device for connecting multiple Ethernet devices together and making them act as a single network segment. A hub works at the physical layer (layer 1) of the OSI model.[1]

A network hub is an unsophisticated device in comparison with, for example, a switch. A hub does not examine or manage any of the traffic that comes through it: any packet entering any port is rebroadcast on all other ports.[2] Effectively, it is barely aware of frames or packets and mostly operates on raw bits. Consequently, packet collisions are more frequent in networks connected using hubs than in networks connected using more sophisticated devices

Front 31

What is a switch?

Back 31

A network switch or switching hub is a computer networking device that connects network segments.
The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer (layer 2) of the OSI model. Switches that additionally process data at the network layer (Layer 3) and above are often referred to as Layer 3 switches or multilayer switches.

Forward data link layer frames based on MAC Addresses to the correct ports to avoid collisions.

Front 32

What can be measured with iperf?

Back 32

- Latency (response time or RTT): can be measured with the Ping command.
- Jitter (latency variation): can be measured with an Iperf UDP test.
- Datagram loss: can be measured with an Iperf UDP test.

The bandwidth is measured through TCP tests.

Front 33

Tell me about RTP.

Back 33

The Real-time Transport Protocol (RTP) defines a standardized packet format for delivering audio and video over IP networks. RTP is used extensively in communication and entertainment systems that involvestreaming media, such as telephony, video teleconference applications, television services and web-based push-to-talk features.

RTP is used in conjunction with the RTP Control Protocol (RTCP). While RTP carries the media streams (e.g., audio and video), RTCP is used to monitor transmission statistics and quality of service (QoS) and aids synchronization of multiple streams. RTP is originated and received on even port numbers and the associated RTCP communication uses the next higher odd port number.

RTP is one of the technical foundations of Voice over IP and in this context is often used in conjunction with a signaling protocol which assists in setting up connections across the network.

RTP was developed by the Audio-Video Transport Working Group of the Internet Engineering Task Force (IETF) and first pu

Front 34

Tell me about NAT

Back 34

In computer networking, network address translation (NAT) is the process of modifying IP address information in IP packet headers while in transit across a traffic routing device.

The simplest type of NAT provides a one to one translation of IP addresses.

To avoid ambiguity in the handling of returned packets, a one-to-many NAT must alter higher level information such as TCP/UDP ports in outgoing communications and must maintain a translation table so that return packets can be correctly translated back.

Front 35

What are some of the NATting methods?

Back 35

1. Full-cone NAT, also known as one-to-one NAT
2. (Address) restricted cone NAT
3. Port-restricted cone NAT
4. Symmetric NAT