Term
| What is each PPP session required to provide to establish a point-to-point connection over Ethernet? |
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Definition
| Each PPP session must learn the MAC address of the remote peer and establish a unique session identifier. |
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Term
| What is the first phase in initiating a PPPoE session? |
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Definition
| The CPE router must first perform Discovery to identify the MAC address of the device to which it must build a peer relationship. It must establish a PPPoE SESSION_ID. |
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Term
| What are the 4 basic steps in the Discovery phase? |
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Definition
1. The PPPoE client sends a PPPoE Active Discovery Initiation (PADI) packet requesting service. The destination MAC address is set to broadcast. 2. The aggregation router responds with a PPPoE Active Discovery Offer (PADO) packet describing offered service(s). The destination MAC address is unicast to the originating client. 3. The PPPoE client sends a unicast PPPoE Active Discovery Request (PADR) to the aggregation router. The request is to move on to the Session phase. 4. The aggregation router sends a unicast PPPoE Active Discovery Session-Confirmation to the client. This assigns a Session-ID and confirms progression to the Session phase. |
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Term
| What is the Maximum Receivable Unit (MRU) for PPPoE negotiated payload size at? |
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Definition
| The MRU for PPPoE negotiated payload size is at 1492 bytes. The PPPoE header is 6 bytes in length with a Protocol-ID field of 2 bytes. |
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Term
| What are the 3 options available to a DSL subscriber using PPPoE? |
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Definition
- Placing a DSL-capable router at the subscriber home - Placing a non-DSL-capable router at the subscriber home, and using a second router for DSL - Placing an external DSL modem at the subscriber home to terminate the DSL connection, and using PPPoE client software. |
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Term
| What type of framing and encapsulation is used with PPPoA? |
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Definition
| PPPoA uses ATM adaption layer 5 (AAL5) framing along with Logical Link Control/Subnetwork Access Protocol (LLC/SNAP) encapsulation on virtual circuits. |
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Term
| How does ATM differ from other methods of L2 encapsulation? |
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Definition
| The only real difference from ATM and other L2 encapsulation methods is the added step of segmentation and reassembly (SAR), where the cells are actually broken up into 48-bytes, plus the 5-byte headers. |
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Term
| Describe how basic ATM circuits are identified. |
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Definition
| ATM uses virtual circuits that are identifed by unique connection identifiers. Each connection identifier is a pair of numbers denoting both a virtual path identifier (VPI) and a virtual circuit identifer (VCI). |
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Term
| What command enabled PPPoE and allows PPPoE sessions to be created through the specified interface? |
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Definition
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Term
| What is the difference between the inside local and inside global NAT addresses? |
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Definition
- Inside local - Configured IP address assigned to a host on the inside network. - Inside global - The IP address of an inside host as it appears to the outside network |
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Term
| What is the difference between the outside local and outside global NAT addresses? |
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Definition
- Outside local - The IP address of an outside host as it appeats to the inside network. - Outside global - The configured IP address assigned to a host in the outside network. |
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Term
| Describe the basic use of VCMultiplexed PPP over AAL5. |
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Definition
| VC-MUX or AAL5MUX specifies the capability to create a per-protocol virtual circuit to transport payloads for differing routed protocols. |
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Term
| Descibe the basic use of LLC Encapsulated PPP over AAL5. |
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Definition
| This methodology uses a single virtual circuit to transport all protocols. The LLC encapsulation technique provides a means to define a protocol number inside the LLC header, which allows the payload to be identified as containing a particular protocol. |
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Term
| What 3 pieces of information are contained inthe LLC header? |
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Definition
- Destination service access point (DSAP) - used for OSI network layer protocols such as Connectionless Network Service (CLNS) - Source service access point (SSAP) - used for OSI network layer protocols. - Frame type - denotes the type of frame in use and therefore its structure. |
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Term
| What command is used on an ATM interface to enable the LLC encapsulation PPP technique? |
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Definition
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Term
| What command sets an ATM interface to auto-detect the DSL modulation method to be used? |
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Definition
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Term
| What is a virtual template and how is it used with PPP configurations? |
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Definition
Virtual templates are logical interfaces that provide characteristics to physical interfaces under their control. The virtual-template interface is configured with all relevant PPP characteristcs and parameters. |
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Term
| Describe the process of framing and line coding. |
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Definition
| Framing is the process of placing the bits in a formalized, predetermined order. Line coding is the process of actually transmitting the bits. |
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Term
| Which command can be used to see the current VPI and VCI in the ATM packets? |
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Definition
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Term
| What command is used to show the current state of ATM traffic hitting the interface and the encapsulation type? |
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Definition
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Term
| What are the 3 distinct phases PPP connections go through during negotiations? |
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Definition
- Link Control Protocol (LCP) phase - Parameters related to establishing, configuring, and testing the connection are negotiated. - Autnetication phase - User authentication is performed according to the methodology negotiated in the LCP phase. - Network Control Protocol (NCP) phase - Network layer protocol negotiation is performed to set up individual control protocols for each L3 protocol to be transported. |
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Term
| Which phases of the PPP negotiation process are mandatory? |
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Definition
| The Link Control Protocol (LCP) and Network Control Protocol (NCP) phases are mandatory phases of the PPP negotiation process. The Authentication phase is optional |
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Term
| What command is used to choose the physical ethernet interface for the PPPoE client dialer interface? |
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Definition
| pppoe-client dial-pool-number pool-number |
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Term
| What command is used to enable PPP encapsulation on a dialer interface? |
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Definition
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Term
What command is used to enable PAP authentication on an interface? |
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Definition
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Term
| What command enables outbound PAP user authentication with a user and password? |
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Definition
ppp pap sent-username username password password |
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Term
| What command enables outbound CHAP user authentication? |
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Definition
| ppp authentication chap callin |
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Term
| What command configures the CHAP username? |
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Definition
| ppp chap hostname hostname |
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Term
| What command sets the CHAP password? |
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Definition
| ppp chap password password |
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