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42 Cards in this Set
- Front
- Back
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2 kinds of VPN's:
Site to Site Internet VPN: Connects two sites of the same enterprise. |
2 kinds of VPN's:
Access VPN: Supports a home or small office user with the remote offices PC typically encrypting the packets |
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Cisco ASA:
Adaptive Security Appliance An appliance that covers many security products including; Antivirus, Antispyware, Antispam, Antifishing, URL Filtering and Email filtering. |
NAC:
Network Admission Control |
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IP is a network layer protocol
TCP is a transport layer protocol |
protocols in a dedicated lease line:
PPP, HDLC, SLIP |
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Protocols in a circuit switched connection:
PPP, HDLC, SLIP |
Protocols in a Packet Switched connection:
Frame Relay, X.25 |
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Protocols in a Cell Switched Connection:
ATM |
Data Link Layer (layer 2) is seperated into :
802.2 LLC 802.3 MAC |
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Repeater is a Layer 1 device
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Switches are Layer2 devices because they look at the Ethernet headers.
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Nic's, Routers, WAP and Network attached printers are similar devices.
Switches and Hubs are similar devices. |
similar devices get crossover cables, dissimilar devices get straight through cables.
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Gigabit cabling crosses over pair 4&5 with 7&8 to make a crossover.
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GBIC: Gigabit Interface Converters
SFP: Small Form Pluggables |
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In a MAC address bytes 1,2,3 (of the 6 bytes total) are the OUI.
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OUI
Organizationally Unique Identifier |
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An Ethernet Frame does NOT include a TYPE field.
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The FCS (Frame Check Sequence) is the only field in the Ethernet trailer
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OSI Layer 1 'Physical Layer' efines the details of how to move data from one device to another.
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Point to Point WAN links provide basic connectivity between 2 points.
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Routers connect to a CSU/DSU with a short cable.
The CSU/DSU represents the Demarcation point. The much longer wire from the tel-co gets plugged into the CSU/DSU. |
CSU/DSU:
External Chanel Service Unit/Data Service Unit. |
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CPE:
Customer Premise Equipment Refers to devices that are at the customers site from the perspective of the Tel-co. |
The cabling between the Telco and the CSU/DSU uses an RJ-48 connector.
RJ-48 is the same plug as an RJ-45 but with different pin-outs. |
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Many Cisco routers support serial interfaces that have an internal integrated CSU/DSU.
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Synchronous circuits - impose time ordering at the links sending and receiving ends.
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When ordering a new line the clock speed of the line must be selected. The CSU/DSU must be synchronized across the link.
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Synchronization occurs between the 2 CSU's on a leased line by having one CSU/DSU (The slave) adjust its clock rate to the other (the master).
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DCE
Data Communication Equipment The device that provides the clocking in the CSU/DSU. |
DTE
Data Terminal Equipment The device that receives the clocking in the CSU/DSU. |
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DCE
Data communication equipment performs the clocking function. |
DTE
Data Terminal Equipment is receiving the clocking. |
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standard HDLC has no field type in the data header.
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Cisco version of HDLC has a field type in the data header.
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PPP behaves like HDLC, theframing looks identical to Cisco HDLC
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PPP checks for errors and discards when found.
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PPP has a 2 bit protocol field.
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PPP is the prefered data link layer of choice when connecting CISCO and non-Cisco routers over a point to point connection.
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T1 - a line from a telco at 1.544Mbps
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E1 The European standard. 2.048Mbps & 32 64 kbps channels
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Point to point leased lines can be described as:
leased line, leased circuit, link, serial link, serial line, point to point link and circuit |
4 wire circuit:
A line from the telco with 4 wires composed of 2 twisted pair wires. |
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Packet Switching Service:
A class of WAN services different from leased lines that allows a large number of routers to be connected to the packet switching service. |
2 types of packet switching services:
Frame Switching ATM (Asynchronous Transfer Mode) |
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Frame Relay:
Allows multiple connections to a single serial interface of a router. cheaper then point to point. |
Frame Relay networks are multicast networks.
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To install frame relay a leased line is installed between each router and a nearby frame relay switch.
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The equipment at the telco examines the data frames sent by a router.
A telco does NOT examine the data sent through point to point links. |
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Each frame relay header holds an address field called a data link connection identifier (DLCI)
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The WAN switch forwards the frames based on the DLCI
DLCI - Data Link Connection Identifier. |
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Frame Relay is considered a form of packet switching.
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LAPF - Link Access Procedure Frame
Protocol identifying the Frame Relay header and Trailer. |
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With Frame Relay the frame relay switches are called DCE and the customer routers are DTE
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When a router needs to forward a packet to another router it encapsulates the layer 3 packet into a frame relay header and trailer and then sends the frame.
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Virtual Circuit -
The logical path a frame travels between each router in a Frame Relay is a virtual circuit |
The logical path a frame travels between a pair of routers is called a Frame Relay Virtual Circuit.
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CIR -
Committed Information Rate - A guarantee by the service provider that a particular VC gets at least so much bandwidth. |
TCP Sliding window:
The window size indicates how many segments can be sent before an acknowledgment will be sent. |
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The Network layer deals with LOGICAL addressing.
An IP address is a layer 3 address |
IP addresses are LOGICAL addresses.
An IP address is a layer 3 address |
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Layer 3 protocols:
IP, IPX, ICMP, OSPF, IGRP, EIGRP, RIP, ISIS |
OSPF, IGRP, EIGRP, RIP, ISIS
are dynamic routing protocols Dynamic routing protocols learn about remote networks and make decisions on best paths between networks. |
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Layer 2 devices include switches and bridges
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Encapsulation:
Layer 1 (Physical) - Bit Layer 2 (Data Link) - Frame Layer 3 (Routing) - Packet Layer 4 (Network) - Segment |
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TCP/IP Model has 4 layers:
Application Transport Internet Network Interface |
The routing process uses the data link layer to encapsulate layer 3 packets into layer 2 frames for transmission across each successive data link.
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IP is a connectionless protocol
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TCP is a connection Oriented Protocol
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Important fields in the IP packet header:
TTL, protocol, Source address and Destination address. |
TTL field - Time to Live Field
A value used to prevent routing loops. |
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RoutING protocol -
learns routes and puts them in a routing table |
RoutED Protocol -
defines the type of packet forwarded or routed through a network. |
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Network layer utilities:
ARP (RARP), DNS, DHCP, PING |
Convergence - The time between when a router looses a route and finds a new one.
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TCP/IP Transport layer features:
Multiplexing using ports: function that allows receiving hosts to choose the correct application for which the data is destined based on the port number. |
TCP/IP Transport Layer features:
Error recovery (reliability), Flow control, connection establishment and termination, ordered data transfer and segmentation. |
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TCP relies on IP for end to end delivery of the data.
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A socket needs:
An IP address A transport protocol A port number |
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Forward Acknowledgment -
In TCP windowing, when the sequence and acknowledgement fields count the number of bytes and only acknowledge at set intervals. |
PAR -
Positive Acknowledgement and Retransmission - Used to describe the error recovery and windowing process TCP uses. |
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MTU -
Maximum transmission Unit: the MTU is the size of the largest layer 3 packet that can fit inside a frame data field. For many data link protocols the MTU size is 1500 bytes. |
UDP -
User Datagram Protocol A connectionless and provides no reliability, no windowing, no reordering of the recieved data and no segmentation of large chunks of data. |
