CCNA - Wide Area Networks
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What is the proprietary default serial encapsulation used on Cisco routers?
HDLC or High-Level Data-Link Control
What is a Virtual Private Network (VPN)?
the creation of private networks across the Internet, enabling privacy and tunneling of non-TCP/IP protocols
Identify the serial WAN connections that are most widely used.
What are the 3 PPP Data Link layer protocols?
- Network Control Protocol (NCP) - defines the network layer protocols
- Link Control Protocol (LCP) - a method of establishing, configuring, maintaining, and terminating the point-to-point connection
- High-Level Data-Link Control (HDLC) - the MAC layer protocol that encapsulates the packets
Whare are the different Frame Relay encapsulations.
___ is the rate, in bits per second, at which the Frame Relay switch agrees to transfer data.
What are the commands for verifying Frame Relay?
- show frame-relay lmi - will give you the LMI traffic statistics exchanged between the local router and the Frame Relay switch.
- show frame pvc - will list all configured PVCs and DLCI numbers.
Describe the WAN Term Customer Premises Equipment (CPE)
equipment that is owned by the subscriber and located on the subscriber's premises
Describe the WAN Term Local Loop.
connects the demarc to the closet switching office, which is called the central office or CO.
The ________ _____ is the precise spot where the service proider's responsibility ends and the CPE begins.
demarcation point (aka demarc)
Describe the WAN term Toll Network.
a toll network is a trunk line inside a WAN provider's network. this network is a collection of switches and facilities owned by the ISP.
Describe the WAN term Central Office (CO).
connects the customer's network to the provider's switching network. Go to know is that <answer> is sometimes reffered to as a point of presence (POP).
These are usually referred to as a point-to-point or dedicated connection. A pre-established WAN connection that goes from the CPE through the DCE switch then over to the CPE of the remote site.
This is a WAN switching method that allows you to share bandwidth with other companies to save money. Also thought of as a network that is designed to look like a leased line.
When you hear the term ____ _______, think phone call.You only pay for the time you acually use. No data can tranfer before an ene-to-end-connection is established. ____ _____ uses dial-up modems or ISDN.
____ uses a combination of both circuit switching and packet switching.
MPLS (MultiProtocol Label Switching)
What are the three layer 2 protocols that Cisco supports on their serial interfaces?
This protocol was created for time-sensitive traffic, providing simultaneous transmission of voice, video, and data. It uses cells that are fixed 53 bytes long instead of packets and can also use isochronous clocking to help the data move faster.
ATM - Asynchronous Transfer Mode
What are the most prominently known WAN protocols used today?
This high-perfomance Data Link, packet-switched technology can be more cost effective than point-to-point links and run at speeds of 64Kbps up to 45Mbps (T3). This also provides features for dynamic bandwidth allocation and congestion control.
This protocol is a data-carrying mechanism that emulates some properties of a circuit-switched network over a packet-switched network and imposes labels (numbers) to packets and then uses those labels to forward packets.
MPLS - MultiProtocol Label Switching
____ is a set of digital services that transmit voice and data over existing phone lines.
- ISDN - Integrated Services Digital Network
____ _____ _____ is a technology used by traditional telephone companies to deliver advanced services over twisted-pair copper telephone wires. It typically has lower data carrying capacity than HFC networks, and data speeds can be range limited by line lenghts and quality.
DSL - Digital Subscriber Line
_____ was created to be a connection-oriented protocol at the Data Link layer for use with X.25, but it can also be used as a simple data link transport. ____ tends to create a tremendous amount of overhead due to its strict time-out and windowing techniques.
LAPB - Link Access Procedure, Balanced
This Hybrid fibre-coaxial, of HFC, is a telecommunications industry term for a network that incorporates both optical fiber and coaxial to create a broadband network.
____ is used with ISDN at the Data Link layer as a protocol for the D (signaling) channel. ____ was derived from the LAPB protocol and is designed primarily to satisfy the signaling requirements of ISDN basic access.
LAPD - Link Access Procedure, D-Channel
This protocol encapsulates PPP frames in Ethernet frames and is usually used in conjunction with ADSL services. It also provides a lot of the familiar PPP features like authentication, encryption, and compression, but has a lower MTU than standard Ethernet.
- PPPoE - Point-to-Point Protocol over Ethernet
____ was derived from Synchronous Data Link Control (SDLC). ____ works at the Data Link layer and creates very little overhead compared to LAPB.
High-Level Data-Link Control (HDLC)
This is where all cable signals are received, processed, and formatted. The signals are then transmitted over the distribution network.
These are relatively small service areas that usually range in size from 100 to 2,000 customers. Typically composed of a mixed, fiber-coax, or HFC architecture with optical fiber substituting for the _____ ______ trunk portion.
___ is a pretty famous, indsutry-standard protocol. Because all multiprotocol versions of HDLC are proprietary, ___ can be used to create point-to-point linkes between different vendors' equipment. It uses a Network Control Protocol field in the Data Link header to identify the Network layer protocol and allows athentication and multiplink connections to be run over asynchronous and synchronous links.
PPP - Point-to-Point Protocol
All cable modems and like devices have to measure up to this standard.
DOCSIS - Data Over Cable Service Interface Specification
This DSL Category has different transmission speeds, occur between two ends of a network - downstream speed is usually faster.
ADSL - Asymmetrical DSL
This DSL group type's speed for both downstream and upstream connections are equal, or symmetrical.
SDLS - Symmetrical DSL
This Cisco solution employs something called VDSL (Very High Data Rate Digital Subscriber Line) technology to significantly expand Ethernet service capacity.
Cisco Long Range Ethernet (LRE)
WAN serial connectors use ____ ________, something that takes place 1 bit at a time over a single channel.
What speeds can LRE achieve and at what distance?
- from 5Mbps to 15Mbps (full duplex)
- distances up to 5,000 feet over existing twisted-pair wiring
______ _________ can pass at least 8 bits at a time, but all WANs use serial transmission.
What are the several different types of connectors?
- V.35 (used to connect to a CSU/DSU)
What is the Cisco proprietary connector that Cisco routers use that you must get from Cisco?
60-pin serial connector
PPP contains what four main components?
- eia/tia-232-c, v.24, v.35, and ISDN
- HDLC - a method for encapsulating datagrams over serial links.
- LCP - A method of establishing, configuring, maintaining, and terminating the point-to-point connection.
- NCP - A method of establishing and configuring different Network layer protocols designed to allow the simultaneous use of multiple Network layer protocols.
By default, router interfaces are ___ ______ ________, and they connect to ____ ________ ________ like a channel service unit/data service unit (CSU/DSU).
- Data Terminal Equiment (DTE)
- Data Communication Equipment (DCE)
What does the DCE network provide to the router?
clocking via the CSU/DSU
Popular ISO-standard, bit oriented, Data Link layer protocol.
High-Level Data-Link Control (HDLC)
What's the basic purpose of PPP?
to transport layer 3 packets across a Data Link layer point-to-point link, and it's nonproprietary
Describe the 3 layers of the PPP stack
- 1 - physical layer such as EIA/TIA, ISDN)
- 2 - Network Control Protocol (NCP), Link Control Protocol (LCP) and High-Level Data-Link Control Protocol (HDLC)
- 3 - Upper-layer Protocols (such as IP, IPX, AppleTalk)
What are the four main components of PPP?
- a physical layer international standard for serial communication
- a method for encapsulating datagrams over serial links
- a method of establishing, configuring, maintaining and terminating the point-to-point connection
- a method of establishing and configuring different Network layer protocols
What must you configure on your router if you have a Cisco router and a non-Cisco router connected with a serial connection?
PPP or another encapsulation method, such as Frame Relay, because the HDLC default is proprietary to Cisco and just won't work.
What are the 4 Link Control Protocol (LCP) configuration options?
- error detection
- ppp callback
What is used to increase the throughput of PPP connection?
Compression - compressing the data or payload prior to transmission.
What is the option that tells the calling side of the link to send information that can identify the user?
This option uses Quality & Magic Number options to ensure a reliable, loop-free data link.
Starting with IOS version 11.1, this option is supported on PPP links with Cisco routers and makes several separate physical paths appear to be one logical path at layer 3.
With this option enabled, a calling router (client) will contact a remote router (server) and authenticate
What are the three phases of session establishment that links go through when PPP connections are started?
- 1. Link establishment phase
- 2. Authentication phase (optional)
- 3. Network layer protocol phase
What are the two methods of authentication that can be used with PPP links?
- PAP - Password Authentication Protocol
- CHAP - Challenge Handshake Authentication Protocol
What are the two separate bandwidth specifications with Frame Relay?
- Access Rate
- Committed Information Rate (CIR)
What is Access Rate?
The maximum speed at which the Frame Relay interface can transmit.
What is CIR (Committed Information Rate)?
The maximum bandwidth of data guaranteed to be delivered. Or the average amount that the service provider will allow you to transmit.
What are the two encapsulation types?
- Internet Engineering Task Force (IETF)
Frame Relay operates using _____ _______ as opposed to the actual circuits that leased lines use.
What are the two types of virtual circuits?
- Permanent (PVCs)
- Switched (SVCs)
How are Frame Relay PVCs identified to DTE end devices?
Data Link Connection Identifiers (DLCIs)
What is Inverse ARP (IARP) used for?
IARP is used to map a known DLCI to an IP address.
What do DLCI's do?
Identify the logical circuit between the local router and a Frame Relay switch.
Describe Local Management Interface (LMI)?
LMI is a signaling standard used between your router and the first Frame Relay switch it's connected to. Allows for passing information about the operation and status of the virtual circuit between the provider's network and the DTE (your router).
Describe LMI Keepalives.
These verify that data is flowing on the PVC.
Describe the LMI communication information about the status of virtual circuits.
This provides DLCI status. That status inquires and messages are used as keepalives when there is no regular LMI traffic to send.
Describe the LMI communication information about Global Addressing.
This provides global significance to DLCIs, allowing the Frame Relay cloud to work exactly like a LAN.
There are three different types of LMI message formats. What are they?
Describe the LMI communication information for Multicasting.
This is an optional extension of the LMI specification that allows, for example, the efficient distribution of routing information and ARP requests over a fraame relay network. Multicasting uses the reserved DLCIs from 1019 through 1022.
Describe Discard Eligibility (DE).
Packets exceeding the CIR are eligible to be discarded if the provider's network is congested at the time. The excessive bits are marked with a DE bit in the Frame Relay header. If the provider's network happens to be congested, the Frame Relay switch will discard the packets with the first DE bit set.
What are the three Frame Relay Congestion control bits?
- Discard Eligibility (DE)
- Forward Explicit Congestion Notification(FECN)
- Backward Explicit Congetion Notification (BECN)
What are the two types of subinterfaces when dealing with Frame Relay?
- Point-to-point - Used when a single virtual circuit connects one router to another. Each point-to-point subinterfaces requires it's own subnet
- Multipoint - This is when the router is the center of a star of virtual circuits that are using a single subnet for all routers' serial intefaces connected to the frame switch.
What are the three different categories of VPN's?
- Remote Access VPNs - These VPNs allow remote users like telecommuters to securely access the corporate network wherever and whenever they need to.
- Site-to-site VPNs - Or intranet VPNs, allow a company to connect it's remote sites to the corporate backbone securely over a public medium like the Internet instead of requiring more expensive WAN connections like Frame Relay.
- Extranet VPNs - allow an organization's suppliers, partners, and customers to be connected to the corporate network in a limited way for business-to-business (B2B) communications.
What are the four most common tunneling protocols?
- Layer 2 Forwarding (L2F)
- Point-to-Point Tunneling Protocol (PPTP)
- Layer 2 Tunneling Protocol (L2TP)
- Generic Routing Encapsulation (GRE)
What are the two primary security protocols used by IPSec?
- Authentication Header (AH)
- Encapsulation Security Payload (ESP)
Describe Authentication Header (AH)
AH provides authentication for the data and the IP header of a packet using a one-way hash for packet authentication. AH checks the entire packet, but it doesn't offer any encryption services.
What are the four components of Encaspulating Security Payload (ESP)?
- Data Origin authentication and connectionless integrity
- Anti-replay service
- Traffic Flow
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