350-022 - CCIE Service Provider DSL Exam
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A DSL subscriber says that his DSL modem is trained at the subscribed rates, 1024 kbps downstream and 256 kbps upstream, but he has no access to the internet. The internet service was working until today. The modem remains trained - it is not dropping train or frequently retraining. Manually retraining the modem does not correct the problem. The customer can ping from his PC to the Ethernet interface on the DSL modem, but not addresses "in the network". Initial troubleshooting shows that the DSL modem can ping the subscriber's PC, but no addresses in the network. What could cause this problem?
There is a problem with the subscriber's ATM PVC between the DSLAM and ATM switch. An incorrect VCI was assigned between the DSLAM and ATM switch shortly after midnight, during the service provider's network rearrangements.
What will significantly degrade DSL performance, regardless of DSL rate or line length?
Radio-frequency filters on the telephone line
While entering commands on a console, the break key is pressed accidentally and the router reboots. What action could disable this problem?
Change the configuration register.
In order to avoid loops when sending routing updates, what is the correct technique to prevent a network from being forwarded on the same interface it is learned?
What is the difference between AAL5 SNAP and AAL5 MUX virtual circuits?
SNAP allows multiplexing of multiple protocols over a single VC, while AAL5 MUX can carry only one protocol per VC.
What is the use of a VC class in IOS configuration?
It defines a template for virtual circuits which can be applied to a (sub)interface such that all PVCs on that (sub)interface which will inherit the configuration from that template.
The ATM reference model is composed of which ATM layers? (multiple answer)
ATM adaptation layer
A DSL line status report shows a high number of corrected and uncorrected errors. The line is configured at 4 milliseconds interleave delay and 4 FEC check-bytes. To reduce the number of uncorrected errors without a detailed analysis of whether the errors are continuous or "bursty", which of the following should provide improved error correction?
Change the interleave delay to 16 milliseconds and the FEC check-bytes to 16
A subscriber complains that his DSL rates are slower than the service he ordered. The customer ordered ADSL at 1 mpbs downstream and 256 kbps upstream, but the maximum bitrate observed during file downloads is 100 kbps downstream. Of the following four choices, which is clearly the most appropriate information needed to begin troubleshooting the problem?
The actual DSL rate that is reported when the DSL line is trained
ATM carries IP and PPP information within ATM cells. What ATM Adaptation Layer is used when an ATM cell carries IP packets and PPP frames?
In Frame Relay, the BECN bit is set by:
The Frame Relay network, in frames traveling in the opposite direction from those frames that encountered congestion
The configuration register does NOT retain settings for:
An enabled AUX port
A DSL customer has subscribed to a service that provides 2 mbps downstream and 256 kbps upstream. The cable length is 10 kft (3 km). The customer reports that file transfers on the DSL line seem slower than normal in recent days. After reviewing the DSL profile parameters for the DSL port, and the actual status of the line, what is the possible reason why the subscriber's data rates are slower than usual?DSLAM#show dsl int atm 1/1DMT profile parametersMaximum Bitrates:Interleave Path: downstream: 2048 kb/s, upstream: 256 kb/sFast Path: downstream: 0 kb/s, upstream: 0 kb/sMinimum Bitrates:Interleave Path: downstream: 0 kb/s, upstream: 0 kb/sFast Path: downstream: 0 kb/s, upstream: 0 kb/sMargin: downstream: 6 dB, upstream: 6 dBInterleaving Delay: downstream: 16000 usecs, upstream: 16000 usecsCheck Bytes (FEC):Interleave Path: downstream: 16, upstream: 16Fast Path: downstream: 0, upstream: 0R-S Codeword Size: downstream: auto, upstream: autoTrellis Coding: DisabledOverhead Framing: Mode 3Operating Mode: AutomaticTraining Mode: QuickMinrate blocking: DisabledSNR Monitoring: DisabledStatus:Bitrates:Interleave Path: downstream: 640 kb/s, upstream: 256 kb/sFast Path: downstream: 0 kb/s, upstream: 0 kb/sMargin: downstream: 6 dB, upstream: 9 dBAttenuation: downstream: 45 dB, upstream: 31 dBInterleave Delay: downstream: 16000 usecs, upstream: 16000 usecTransmit Power: downstream: 19.4 dB, upstream: 12.0 dBCheck Bytes (FEC):Interleave Path: downstream: 16, upstream: 16Fast Path: downstream: 0, upstream: 0R-S Codeword Size: downstream: 1, upstream: 8Trellis Coding: Not In UseOverhead Framing: Mode 3Line Fault: NONEOperating Mode: ITU G dmt Issue 1Line Type: Interleaved Only
The signal-to-noise margin on the line will not allow downstream DSL rates faster than 640 kbps. If the subscriber's service was in fact faster at some time, then something has changed in the line characteristics or noise spectrum.
Inferface FastEthernet 0/0/0ip address 192.168.1.1 255.255.255.0!interface ATM 0/0/0.30 multipointpvc 1/43encapsulation aal5ciscoppp Virtual-Template 2!!interface Virtual-Template 2ip unnumbered FastEthernet 0/0/0no peer default ip addressppp authentication pap chapppp ipcp mask 255.255.255.224!Refer to the configuration above. A customer connected to PVC 1/43 boots their CPE (PPPoA encapsulation). The Radius server is properly configured and recognizes the customer. The Radius server assigns the Framed-IP-netmask 192.168.10.1/29. What information does the CPE receive from the NRP via PPP IPCP negotiation?
192.168.10.1 IP Address, subnet mask 255.255.255.248
Every time a typing mistake is made at the exec prompt of a router, the message from the router indicates a lookup is being performed. Also, there is a waiting period of several seconds before the next command can be typed. Can this behavior be changed?
Yes, use the no ip domain-lookup command.
When a TCP segment is lost, the TCP sender reacts by: (multiple answer)
Resending the segment
Increasing the amount of time it will wait when timing out the next segment that is sent
What Q.931 message cannot be received in response to sending a Q.931 SETUP message?
What establishes routing table precedence in a routing table?
Which three are major inhibitors of ADSL line quality? (multiple answer)
What is an Inter Switch Link (ISL)?
A Cisco proprietary protocol for interconnecting multiple switches
What happens to an incoming frame on a Layer 2 switch?
The switch looks for an entry in its switching table for the destination MAC address and an associated outgoing port.
All of the following are components of LANE except:
LANE Routing Table (LRT)
What is not a valid service type between an 827 and a 6400?
If a Dialer Profile exists in the local configuration of a router, what is true?
A virtual-access interface will inherit all configurations from the dialer profile.
In Frame Relay, what devices resend packets that do not transmit correctly?
Network end stations
A router interface address is 18.104.22.168 with a mask of 255.255.255.224. What configuration statement will allow this interface to participate in OSPF Area 0?
router ospf 1network 22.214.171.124 0.0.0.31 area 0
The major difference between DMT and CAP is:
CAP uses a single center frequency; DMT is multiple-carrier.
The field of an ATM address that states what type of address is being used is:
CIDR is primarily used:
For classless routing
What is true concerning interleaved versus fastpath mode in DMT DSL service?
Interleaved mode allows greater forward error correction (FEC).
The two label distribution protocols that provide support for MPLS traffic engineering are:
RSVP and CR-LDP
In DMT DSL transmission systems, what is the effect of turning off half of the available downstream carriers (tones)?
The downstream DSL bandwidth is reduced.
Which are the correct ways to release IBGP from the condition that all IBGP neighbors need to be fully meshed? (multiple answer)
Configure route reflectors
Find the problem in the following configuration:vpdn enablevpdn-group 1request-dialinprotocol pppoevirtual-template 2!interface atm 2/0.1 point-to-pointpvc 0/101encapsulation aal5snapprotocol pppoe!interface atm 2/0.2 point-to-pointpvc 0/102encapsulation aal5snapprotocol pppoe!interface atm 2/0.3 point-to-pointpvc 0/103encapsulation aal5snapprotocol pppoe!interface virtual-template 2ip unnumbered Fastethernet 4/0!interface FastEthernet 4/0ip address 172.22.32.1 255.255.255.0
The VPDN-group definition should have the command 'accept-dialin' instead of the command 'request-dialin'.
A DMT DSL modem is working on a "shared line" with standard telephone service (POTS). When the subscriber picks up the telephone handset, the DSL modem untrains, then retrains at a lower DSL line rate. When the telephone is not off-hook, the DSL modem will train at the subscribed rate (normal operation).Which of the following is the probable cause of this symptom?
A microfilter or splitter was not correctly installed between the telephone and the line.
When a subscriber is configured for PPPoE service, the DSL modem is usually configured as:
A basic bridge (RFC 1483 bridging)
BGP can implement a policy of 'Route Dampening' to control route instability. What statement about route dampening is NOT correct?
The history of unstable routes is forwarded back to the sender to control future updates.
What is RPF?
Reverse Path Forwarding
What is true about the DLCI field in the Frame Relay header?
It generally has significance only between the local switch and the DTE device.
Three of the following are common symptoms of a bridge tap ("half tap") on a DSL line. Which three are symptoms that result from placing a bride tap on a DSL line?
The line may not train.
DSL line rates will be lower than expected (lower than provisioned).
The line may have degraded DSL service, but POTS service may appear normal.
With CGMP enabled, which are unique about the following MAC address range: 01-00-5E-00-00-00 to 01-00-5E-00-00-FF? (multiple answer)
CGMP does not prune those MAC addresses.
They contain the CGMP Multicast addresses for the IGMP Leaves and IGMP Queries.
They are the reserved IP addresses of 126.96.36.199 to 188.8.131.52 for forwarding local IP multicast traffic in a single Layer 3 hop.
MPLS does not support:
What VCI value is reserved for PNNI ATM routing?
ATM switches use the VPI/VCI fields of the cell header:
To identify the next intermediate destination to which the cell should be passed
A Network Administrator is unable to configure a PVC with the value of 8/49. He looks at the running config and notices the following entry for the interface he is working with. What is the likely cause of the problem?interface ATM0/0/0no ip addressatm vc-per-vp 2048no atm ilmi-keepalive
Too many bits have been assigned to the VCs reducing the possible values of the VP.
What is NOT a reason to deploy MPLS?
Ubiquitous acceptance and firm standards
The following configuration is from a Cisco DSLAM:interface ATM1/1no ip addressdsl profile basicno atm ilmi-keepaliveatm pvc 2 32 interface ATM0/1 1 32This configuration is from a Cisco 2600 router with an ADSL WIC installed:interface ATM0/0.1 point-to-pointip address 192.168.1.2 255.255.255.0pvc 1/32protocol ip 192.168.1.1 broadcastencapsulation aal5snapThe CPE is connected to DSLAM DSL port 1/1 via a DSL line. The subscriber's DSL service is not working correctly. Based on the information shown in these two "show run" output messages, what is the subscriber's trouble symptom?
The ADSL WIC will train up to the DSLAM, but the subscriber can not access the internet.
A DSLAM is using Reed-Solomon forward error correction on a DMT DSL line. The DSL service is using TCP/IP over ATM over DSL. A high number of upstream RS uncorrected errors are occurring on the DSL line, as reported by the DSLAM in the following status message:DSL Statistics:Init Events: 2Transmitted Superframes: near end: 93681573 far end: 0Received Superframes: near end: 93516422 far end: 0Corrected Superframes: near end: 142631 far end: 31571Uncorrected Superframes: near end: 191 far end: 1LOS Events: near end: 0 far end: 0LOF/RFI Events: near end: 0 far end: 0ES Events: near end: 5 far end: 1What is the result of the uncorrected errors?
The errored data resulting from uncorrected layer-1 errors will be handled by TCP.
What ADSL DMT line rate requires (occupies) the most bandwidth on a telephone line?
8 mbps downstream, 800 kbps upstream on 9 kft (2.75 km) of cable.
What does the Service Selection Gateway (SSG) feature on the NRP support to authenticate and authorize users?