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43 Cards in this Set
- Front
- Back
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PPP: What types of links are supported?
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Both synchronous and asynchronous
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PPP: how does PPP support multiple layer-3 protocols?
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Protocol type field in header. Note difference from HDLC.
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PPP: What kinds of authentication are available?
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PAP (clear text) and CHAP
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PPP: Describe 4 features of LCP
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LCP is Link Control Protocol
1. Looped link detection 2. Error detection w/ FCS 3. PPP Multilink bonding 4. Authentication |
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PPP: Three phases of session establishment
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1. Link establishment phase
2. Authentication phase (PAP/CHAP) 3. Network layer protocols phase |
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PPP: CLI global commands needed to configure PPP
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#hostname <name> (reqd. for authentication)
#username <other side hostname> password <other side's password> |
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PPP: CLI interface mode commands to configure PPP
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#interface <type number>
#ppp authentication pap | chap | ms-chap-v2 ppp chap password 0 <password> |
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PPP: 2 CLI commands for debugging
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#debug ppp authentication
#debug ppp negotiation |
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Frame Relay: Define virtual circuit
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Logical path between customer DTEs. Acts like point to point link.
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Frame Relay: Define permanent virtual circuit
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Predefined VC. Equated to leased-line in concept
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Frame Relay: Define switched virtual circuit
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Dynamic VC; setup needed. Equated to dial-up in concept.
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Frame Relay: Define DTE
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Data terminal equipment. Customer equipment using frame relay.
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Frame Relay: Define DCE
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Date communicaitons equipment. Frame relay switches at telco
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Frame Relay: Define Access Link
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Leased line between DCE and DTE
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Frame Relay: Define AR and CIR
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AR is access rate. Clock speed of access link.
CIR is committed information rate. Contractual guarantee of speed. Less than AR |
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Frame Relay: Define DLCI
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Data Link Connection Identifier. Frame relay address used in headers to identify virtual circuit
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Frame Relay: Define NBMA
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Non-broadcast multiple access. Mutliple devices on a network, but no broadcast capability
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Frame Relay: Define LMI and list 4 features.
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Local Management Interface: Protocol used between DTE and DCE to manage connection.
Keepalives, detects link failure, status messages, SVC signaling |
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Frame Relay: What are the 3 LMI protocol standards?
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Cisco
ANSI (T1.617 Annex D) ITU (Q933 Annex A) |
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Frame Relay: Will LMI autonegotiate?
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Yes. This is the most popular setting.
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Frame Relay: Name and describe 2 encapsulation methods.
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Cisco encapsulation adds additional header between LAPF header and layer 3 packet
IETF (RFC 1490/2427 ) encapsulation uses different header |
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Frame Relay: Describe 4 DLCI Addressing Facts
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Single DLCI field in header
DLCIs are locally significant (only have meaning for local access link) Global addressing concept: a way of choosing DLCI numbers Frame relay switches change the DLCI before delivering the frame |
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Frame Relay: Define FECN
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Forward Explicit Congestion Notification: Bit in header, sent to destination
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Frame Relay: Define BECN
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Backward Explicit Congestion Notificaiton: bit in header set in the next frame going back to sender
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Frame Relay: Define DE bit
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Discard eligible. First to be dropped in event of congestion
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Frame Relay: Interface configuration comands
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#interface <type number>
#encapsulation frame-relay #ip address <addr> <mask> #No shutdown |
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Frame Relay: IOS command to map ip address to DLCI
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#frame-relay map ip <ip addr of dest> <dlci> [ broadcast ] [ cisco | ietf ]
broadcast is required if broadcasts or multicasts are sent by the routers (e.g. routing protocols) |
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Frame Relay: IOS command to assign DLCI number to subinterface
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#frame-relay interface-dlci <dlci number> (use this on point-to-point subinterfaces)
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PPP: What two devices do you need to connect a router to ISDN
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Terminal adaptor (TA)
Network Termination Type 1 (NT1) |
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Frame Relay: What happens if the frame-relay lmi-type x commands don't match?
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No autosensing when manually configured. Routers will take the physical link down.
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PPP: Which protocol is responsible for negotiating and managing PPP connections?
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LCP is Link Control Protocol
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Frame Relay: What is the default frequency of LMI keepalive packets?
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10 seconds
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Frame Relay: Default frequence of inverse ARP messages on DLCI
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60 seconds
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Frame relay: Meaning of the DLCI status codes (3) in debug frame-relay lmi
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0x4 - deleted
0x2 added and active 0x0 added inactive |
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Frame Relay: What command will show the frame relay LMI standard in use:
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#show frame-relay lmi.
#Show running-config will not work because LMI is usually determined automatically. |
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Frame Relay: Which command disables the use of frame relay LMI messages
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#no keepalive
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Frame relay: what is the default lmi-type if not configured?
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cisco
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Frame relay: What is the CLI command to show status of the PVCs
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#show frame-relay pvc
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Frame relay: What is inverse ARP and when is it required?
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Inverse ARP creates a mapping between ip address and DLCI; Needed in multiaccess networks when static mapping is not configured. Works by announcing its own IP address when a frame relay circuit comes up.
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Frame relay: What is mapping and when is it needed?
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Mapping correlates the layer-3 IP address with the layer-2 (dlci) address used to reach it. Mapping is needed on multiaccess networks.
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Frame relay: What is the CLI command to show the mapping status?
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#show frame-relay map
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Frame relay: What is the CLI command to turn off inverse ARP?
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interface: #no frame-relay inverse-arp
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Frame relay: debug command to see lmi data exchanges
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#debug frame-relay lmi
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