01-DSLAM Troubleshooting Training ISSUE1.0

7/16/2019 01-DSLAM Troubleshooting Training ISSUE1.0

1/68

1

Huawei

Huawei Technologies Proprietary Confidentiality level: For Internal Use Only

DSLAM Troubleshooting

TrainingISSUE 1.0

Fixed Network Broadband Technical

Support Department


2/68

2

Huawei


Introduction

Do you know about DSLAM equipments of

Huawei?

Do you know about the architecture of HuaweiDSLAM products?

Do you know about the general flow of Huawei

DSLAM troubleshooting?


3/68

3

Huawei


Objectives

Know the general situations of DSLAM

equipment Master the troubleshooting flow of

MA5100

Master the troubleshooting flow of

MA5300

Master the troubleshooting flow of

MA5600

After this course, you should be able to:


4/68

4

Huawei


Reference

MA5100V200R005 Troubleshooting Manual

MA5300V100R005 Troubleshooting Manual

You can get these materials at the website

http://support.huawei.com.


5/68

5

Huawei


Contents

Chapter 1 DSLAM Troubleshooting Flow

Chapter 2MA5100Troubleshooting Flow




6/68

6

Huawei


DSLAM Troubleshooting Flow

1 Architecture of Broadband Network

2 DSLAM Troubleshooting Flow


7/68

7

Huawei


DWDM /METRO

Quidway NE80

Access layer

iManagerTM N2000

L3

Spread users/Old

residential communityDense commercial subscribers

New residential community

LAN

L2

L2 S3026V

MA5600

MA5100MA5300

FE

GE

ADSLFE/GE L2

GE

FE

L2

VDSL

iTELLINTM

BAS

FE/GEFE/GE

LAN

BAS

MA5105

MD5500

PSTN

Networking of Broadband Network

FE/GE


8/68

8

Huawei


DSLAM Troubleshooting Flow

In case of faults, judge whether they occur to DSLAM or to

upper layer equipment first according to the phenomenon. A

correct judgment leads you to the preliminary success. The

troubleshooting flow of DSLAM equipment is detailed below.

For DSLAM equipment faults, the troubleshooting flow is

described at two aspects:

Internet access failure

Slow Internet access


9/68

9

Huawei


DSLAM Fault Internet Access Failure

Check whether allsubscribers on DSLAMfail to access Internet

Y

Upper layer equipmentruns normally

Check whether opticalchannel/transmission is

normal

Check whether maincontrol board/upstream

board runs normally

Restore opticalchannel/transmission

Y

N

Y

Y

Solveproblem

Change slot

position/board

YN

N

N

Check whetherMODEM isactivated

ChangeMODEM/externalline

Test upstream boardwith PC

View port states.If abnormal, reset the

ferrule

Y

N

N

Y

Solveproblem

Y

N

Y

Check/Modify DSLAM dataconfiguration

N

Modify upperlayer data

Y

N

N

Collectinformation

Submit CRMS/Broadband-support Collect

information

Submit CRMS/Broadband-support


10/68

10

Huawei


DSLAM Fault Slow Internet

Whether all subscribers onDSLAM access Internet at

a low speed

Y

Check optical power/workingmode of optical

channel/transmission

Check data/flowinformation of flow

control/CAR and broadcastpacket

Y

N

N

Solveproblem

Y

N

N

Compare accessible rate

with port restricted rate

Punch wires at the near end totest Internet accessing rate

Check subscriber

terminal

Check flow control/CAR

information

Y

N

N

Problem issolved

Y

N

Y

Reset

ferrule/board

N

Y

Capture packet

on upstream

board

Modify CAR/flow

control data

Y

N

Y

N

Modify CAR/flow

control

N

Y

Capture packet on

upstream board

Y

Upper layer equipment

runs normally

Collect

information

Submit CRMS/

Broadband-support

Restore opticalchannel/transmission


11/68

11

Huawei


Fault Information Collection

In collection of fault information, please refer to XXX Product

Fault Information Collection Guide at the website

support.huawei.com, collect the information by service types

and fault phenomenon, and feed back to CRMS or mail to

[email protected].
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]


12/68

12

Huawei


Problems

Which layers are the broadband network divided

into? And which layer is the DSLAM located in?

How to solve the problem that all users cannot

access the Internet/access the Internet at a low

speed when the DSLAM is faulty?


13/68

13

Huawei


Course Content


Chapter 2 MA5100 Troubleshooting Flow




14/68

14

Huawei


MA5100 Troubleshooting Flow

1 LAN upstream Failure Internet

Access Failure

2 LAN upstream Failure

Slow

Internet Access


15/68

15

Huawei


Categories of Internet Access Failures of

LAN upstream Users

Whether data

configurations are correct

Whether the system,

LAN board and ports are

normal

Whether the opposite

equipment works normally

Whether subscriber

side settings are correct

Analyze Internet

access failure causes


16/68

16

Huawei


Working Modes of LAN Board

Application of LAN Board The LAN board converts ATM cells and Ethernet frames when the

MA5100 uses LAN board upstream.

Being used in IP upstream, the LAN board supports three

working modes:

GENERAL mode: The LAN board can process VLANs, and control

transparent transmission of VLAN information, but supports relatively

less VLANs.

IP-DSLAM mode: The LAN board only transmits VLANs transparently,

supports 2K/4K VLANs and isolates users effectively.

IPCASCADE mode: The LAN can process VLANs, control transparent

transmission of VLAN information, support relatively less VLANs, and

supports neighborhood VLANs (only the LAND).


17/68

17

Huawei


Checking Running of Upper Layer Equipment

Check the upper layer equipment

A faulty upper layer equipment usually affects the users greatly,

that is, users on one or multiple MA5100 cannot access the

Internet. In this case, check the upper layer equipment at the

following aspects:

Working states and port states of the upper layer equipment that is

connected with MA5100

Transmission between the MA5100 and upper layer equipment

States of the upper layer BAS, router and switch. You can test the

address of the upper layer equipment by PING or TRACERT, so as

to locate the problems.


18/68

18

Huawei


Checking Running of Upper Layer

Equipment Test Method

Test Method

Categorize the upper port and another port into the same VLAN, and

set the DEFAULT VLAN ID and VLAN ID of the test port identical.

Connect the PC on the test port, and begin the test.

If the PC can be connected to the Internet, it indicates that no faults

occur to the upper layer equipment and LAN board. You should focus on

checking MA5100.

Set the PC address and user address to the same segment, and

execute the PING commands. If the command is executed successfully,

it indicates that no faults occur to MA5100. You should focus on

checking the settings of the upper layer equipment.


19/68

19

Huawei


Checking Running of System and LAN Board

Whether the working states of the system, LAN board and ports arenormal

A faulty MA5100 or a faulty LAN board affects all users on the MA5100.

In this case, check the working state, board states and alarm information

of MA5100. Check the connection LED on the LAN board port. When the green LED is

always on, it indicates that the connection is normal. When the yellow LED

flashes, it indicates that data is being forwarded. At the same time, you can

query whether the port state of the LAN board is ONLINE or ACTIVE through

the console.

View the alarm information of MA5100, so as to make clear whether faults

occur to the MA5100 or its boards.


20/68

20

Huawei


Checking Running of System and LAN

Board Test Method

For the System

To find whether there are problems in data forwarding through the system,

connect the PC to the ASDL port with a PVC, set the PC address and NMS

address to the same network segment, add the PC address to the system

IP-ACCESS list, and ping the NMS address on the PC.

For the LAN Board

Set the two ports of the LAN board to the same VLAN, set their modes to

UNTAGGED, and make the VLAN ID and DEFAULT VLAN ID of the ports

identical. Connect both ports to the PC, set addresses of the ports to the

same network segment, and ping packets mutually, so as to find whether

there are problems in data forwarding through the LAN board.


21/68

21

Huawei


Checking Data Configuration

Check whether data configuration is correct

Incorrect data configuration usually happens in new deployment or addition of

new users. When problems occur to an online equipment, focus on checking

these two items at the following aspects:

Check whether the working modes (TAGGED/UNTAGGED), VLAN ID and

DEFAULT VLAN ID of the ports are correct. When the upper layer equipment does

not support VLAN, it is necessary to make the VLAN ID and DEFAULT VLAN ID of

the ports identical and make the VLAN self terminate on MA5100. To transmit

VLANs transparently through the ports, it is necessary to set the ports to TAGGED

mode and make the VLAN ID and DEFAULT VLAN ID different.

Check whether the information of the upper layer equipment of MA5100 is correct,

such as the accounts, VLANs and route.

Check whether the PVC of the ADSL subscriber port and the RTU on the

subscriber side are set correctly.


22/68

22

Huawei


Checking Subscriber Side Settings

Check whether the settings of subscriber side are correct

When only some subscribers have difficulties in Internet access, focus on

checking the configurations and states of these subscriber sides.

Check the settings of the equipments on the subscriber side such as the

router and switch. Check whether the network adapters of the subscribers work normally and

connections are normal.

For a dialup subscriber, check the installation and settings of the dialup

software. The Enternet 300 or Enternet 500 software is recommended.

Check the settings of the subscriber address, gateway, DNS and route table

entry.

Check whether the PC is infected by viruses.


23/68

23

Huawei


Internet Access Failure of LAN upstream

Subscriber Case 1

Case: An O/E converter only supports 10-network cables, making LAN board

upstream blocked.

[Phenomenon] For MA5100 IP-DSLAM networking, the LAN board has the FE optical

port connected through the O/E converter. The fiber is placed in the transmission

equipment room. There are about 60M from the data equipment room to the

transmission equipment room. Lack of a tail fiber long enough, place the O/E

converter to the transmission equipment room, and connect to the data equipment

room with a network cable. After installation, you can find that the LINK LEDs on the

O/E converter and LAN board are off.

[Handling]

Remake the connectors at both ends of the network cable, check the sequence, and

measure with the cable tester to prove that the network cable is normal. However, Internet

access still fails.

Adjust the DIP switch on the network port of the O/E converter. There is no response.

Connect a laptop with the LAN board. The connection is normal, indicating that the LAN

board is normal.


24/68

24

Huawei



Subscriber Case 1

Connect the PC with the O/E converter on the MA5100, the LINK LED is off. However,

connect the PC with the O/E converter with the attached short network cable in the

transmission equipment room, the connection is normal.

Read the instruction of the O/E converter, and you can find that the network ports of the

O/E converter only supports the network cables that are 10M long at most.

[Analysis]

Connecting equipments through network cables is usually the easiest mode so long as the

equipment works normally, network ports are kept undamaged, and network cables are not

longer than 100M, being wired correctly on two sides and without any broken cable in the

middle.

In principle, there should be no problems so long as connectors are in good contact.

However, this fault was resulted from the length of the category 5 UTP (the O/E converter

can only support up to 10M category 5 UTP).

Be sure to find the indexes of the equipment before use, for example, to use the O/E

converter, query the supported distance, wavelength, transmitting optical power and

receiving sensitivity of its optical ports, as well as the types and supported network cable

length of its network ports.


25/68

25

Huawei



Subscriber Case 2

Case: VLAN IDs are restricted in transmission, resulting in service failure.

[Phenomenon] For one office, networks are networked in IP upstream mode, go

through the 2.5G transmission equipment of vendor Z, and finally are accessed to

MA5200. Two VLANs were previously set on MA5100 LAN board, namely service

VLAN22 and NMS VLAN65, and services and NMS are normal. In recent capacity

expansion, the office is intended to assign other ports of the LAN board to cybercaf subscribers, but subscribers cannot access the Internet after VLANs are

reassigned to the ports.

[Handling]

Check the data configurations of MA5200 and MA5100. The configurations are

correct.

Define a new subscriber on the LAN board, and assign the VLAN ID 10. This

subscriber cannot access the Internet. Define a subscriber on other LAN board,

and assign the VLAN ID 10. This subscriber still cannot access the Internet.


26/68

26

Huawei



Subscriber Case 2

Define new subscribers on this LAN board and other LAN board, and assign the

VLAN ID 22. The subscribers can access the Internet.

Analyze the packets from MA5100 through sniffer, and you can find that packets

are in a standard format, and carry correct VLAN IDs, proving that the LAN board

works normally.

Define a subscriber with the VLAN ID 65 on the LAN board to check whether the

intermediary transmission equipment sets restrictions. The subscriber can access

the Internet normally.

Consult the engineer from the vendor of the intermediary, and you will learn that

the transmission equipment processes VLANs while processing packets, and you

must preset the VLANs.

Coordinate with the engineer to define the corresponding VLANs. Then, the

subscribers on the LAN board can dial up to the Internet normally.

[Analysis]

Most transmission equipments transmit data transparently, but the transmission

equipments of this office only process the VLAN IDs of packets. Therefore, you

should throw away the traditional ideas for troubleshooting.


27/68

27

Huawei


Fault Categories of Slow Internet Access of

LAN Board upstream Subscriber

Whether upper layer

equipments are congested

Whether equipments

control subscriber flows

Whether ports are

corrected to upper layer

equipments normally

Whether LAN board

ports are congested

Analyze slow

Internet access causes


28/68

28

Huawei


Check Congestion among Upper Layer Equipments

Unstable connections or congestions among upper layer

equipments

Unstable connections or congestions among upper layer equipments may

result in slow Internet access, for example, Internet accessing slows downon MA5100 after some time or with more and more subscribers.

Test method: Know networking conditions, ping the address of the

interfaces of upper layer equipments orderly, observe the packet loss ratio

and delay, and compare with the values in normal cases to find whether

faults occur to the upper layer equipments.


29/68

29

Huawei


Checking Flow Control Settings

Check whether upper layer equipments and MA5100 control

the flows of subscribers.

Under flow control, the downloading ratios of subscribers vary unnoticeably and

usually the same. There are some common flow control modes:

Limit port rates for ADSL subscribers

Control flows by upper layer BAS according to accounts, ports and VLANs

Note: With IP upstream, MA5100 does not support PVC flow control. It is

recommended to limit port rates on MA5100 for ADSL subscribers.


30/68

30

Huawei


Checking Operation of System and LAN Board

Check the system, LAN board ports and upper layer equipments areconnected normally.

Query whether the ports on LAN board work in 100M full duplex. If not, set

100M full duplex forcibly. Otherwise, Internet accessing may slow down in

case of great traffic. And traffics are considerable when LAN board upstream

is used, so it inevitably results in slow Internet access if ports does not work

in 100M duplex.

Be sure to make the network cables between LAN board ports and subscriber

equipments strictly according to requirements. Otherwise, network cables

may fail to satisfy high rate requirements, and packets may loss in case of

great traffics, thereby resulting in slow Internet access.

Query the system alarm messages to find whether there are related alarms.


31/68

31

Huawei


Checking Congestions on LAN Board Ports

Check whether the ports on LAN board are congested.

Due to the limited subscriber line rate, subscriber lines must be

congested when a great amount of broadcast packets, multicast

packets or unknown unicast packets are sent to the subscriber, thereby

resulting in slow Internet access. In this case, monitor the traffic over

lines on the subscriber side through Netxrav or Sniffer, and capture the

data to find the congestion causes.

For ADSL subscribers using LAN board upstream, increase the

subscriber bandwidths and observe the faults to find whether

subscriber lines are congested.

When congestion occurs when many subscribers go through upstream

over multiple ports of one LAN board, you can trunk the multiple ports

on the LAN board to share loads and increase effective bandwidth.

Slow Internet Access of LAN upstream


32/68

32

Huawei


Case: The upstream ports are not separated from VLAN, making slow

Internet access of ADSL subscribers.

[Phenomenon] Subscriber networking: FE port on MA5100 LAN board - LAN Switch

O/E converter - O/E converter - LAN Switch - O/E converter router. During some period

in the evening (19:30 21:00), ADSL subscribers access the Internet at a low speed, with

many ping packets lost and many bandwidth occupied by irrelative broadcast packets or

multicast packets.

MA5100 SwitchO/E

converterO/E

converter

O/E

c

onverte

r

Router

Switch

INTERNET


Subscriber Case 1

Sl I t t A f LAN t


33/68

33

Huawei


[Handling]

To find out whether IP address conflicts result in low Internet, the problem still exists

without any IP address conflict.

Check the working modes of the LAN board and O/E converter of MA5100. All work in

100M full duplex.

To find out whether problems occur because VLANs are not allocated by LanSwitch

(LanSwitch is a lower level D-Link, and cannot allocate VLANs, just equivalent to a HUB

over the network), capture packets on the ADSL subscriber port. Many irrelative

broadcast packets and multicast packets are captured, which occupy many bandwidth

and result in slow Internet access.

Separate VLANs of Lan Switch on the upstream ports, and this problem can be nearly

solved.

[Analysis]

When the IP-DSLAM networking upstream is connected with LAN Switch, the VLANs

must be allocated to separate broadcast packets, instead of simply connected. This is

because many irrelevant packets may occupy effective bandwidth of subscribers and

thereby result in slow Internet access when there are many subscribers.


Subscriber Case 1

Sl I t t A f LAN t


34/68

34

Huawei


A faulty O/E converter results in slow Internet access.[Phenomenon] MA5100 uses IP-DSLAM and ATM upstream modes at the same time. One

hundred and forty-four subscribers are uplinked to IP network nodes through LAN, and other

subscribers are uplinked to the ATM network through the MMX board. Not long after using

these two modes, the Internet accessing speed of LAN board upstream subscribers greatly

decreases, falling from 30Kbit/s to 10Kbit/s or so.

[Handling]

As the ATM upstream subscribers can access the Internet normally, so you can sure that

the problem occurs to the LAN board. Through NMS, log in to this MA5100, and you can

find that the port 7 on the LAN board is connected with a new equipment and alarms are

frequently reported. In onsite check, find that the board is connected with an optical

MODEM for downstream VPN subscribers. Because this equipment is not a auto-

negotiation equipment, it reports a lot of alarms and affects normal use of the LAN board.


Subscriber Case 2



35/68

35

Huawei


[Handling] Change the port mode to a fixed mode that corresponds to the optical

MODEM. The alarms on this port disappear.

Test the subscriber line from the office end measurement room, and find that

the downloading rate has been increased to about 36kbit/s. The problem is

solved.

[Analysis]

The optical MODEM makes a lot of LAN board alarms. In addition, the

upstream cell VLAN includes all the eight ports and cannot separate broadcast

packets. In this case, repeated auto-negotiation of a port may slow down

Internet accessing rate of other subscribers.

For use of the LAN board, try to only set VLANs to the required ports to

prevent unnecessary broadcast problems.


Subscriber Case 2



36/68

36

Huawei


Case: The broadcast packets on the subscriber side make ports

congested, resulting in slow Internet access.

[Phenomenon] The MA5100 of one office is uplinked through the LAN board and

directly connected to layer 3 switch. In this case, subscribers are connected to

the Internet by a fixed IP, and each subscriber is allocated with a public network

address. When ADSL subscribers access the Internet, some packets (2%-7%)are lost, resulting in slow Internet access.

[Handling]

There are three possibility for this problem:

The MA5100 and third party equipment have hardware failures.

Faults occur to communication lines.

Network performances are deteriorated, such as the network storm

(resulting in bandwidth congestion) and malicious attack.


Subscriber Case 3



37/68

37

Huawei


Cause 1: Connect a laptop to one port of the LAN board, and allocate this port to

the same cell VLAN as the upstream port.

Ping the subscriber IP address, and no packets are lost, indicating that the LAN board

works normally.

Ping the gateway (interface address of the third party equipment), and some packets are

lost, indicating that communication lines and third party equipment result in slow Internet

access.

Directly connect the laptop to the third party equipment, directly ping the gateway, and no

packets are lost, indicating that the third party equipment is not faulty.

Set the ports of the equipments on both sides to 100M duplex, and the problem still exists.

From this test, you can find that our third party equipment runs normally.

Cause: After a test, there is no error occurring to the communication line (network

cable) from our equipment to third party equipment. The second possibility is

impossible.


Subscriber Case 3



38/68

38

Huawei


Cause 1: Use Netxry to capture packets. Connect the laptop to one port on the LAN board that is in the same cell VLAN as the

upstream port. Capture packets with Netxray, and many packets with the network

segments of private networks, broadcast packets and multicast packets are captured,

80% to 95% of which came from 192.168.0.0/24 network segment and nearly all are

from 4/9, 5/1, 12/14, 10/15 subscribers of MA5100. Check the networking mode on the

port of the subscriber, and you can find that the subscriber is directly connected with the

LAN through ADSL MODEM, and separate private network from public network through

a MODEM that fails to shield the private network address and results in many private

network packets over the network (about 90%).

Test the backbone equipment and MA5100 again: add an Ethernet switch C between

them, connect a laptop to the Ethernet switch C, and then ping the gateway through the

laptop.


Subscriber Case 3



39/68

39

Huawei


In this case, packet loss ratio reaches 3% to 5%, and that for ping subscriber

address is 0%. Disconnect MA5100, and ping the gateway from PC. In this case,

the packet loss ratio is 0%. This indicates that MA5100 and upper layer equipment

work normally. In addition, MA5100, a layer 2 access equipment, only transmits

subscriber packets to the upper layer equipment without any prior processing.

Therefore, it is mostly possible that the backbone equipment, the layer 3 switch,

has a limited processing capability against packets, resulting in packet loss.

Because the router has a powerful processing capability against packets, the

problem of packet loss can be solved by commissioning the MA5100 to one router

over the backbone network.

[Analysis] Subscribers send a lot of broadcast packets and private network packets that

occupy many network resources and affect the overall network performances,

thereby resulting in packet loss and slow Internet access.


Subscriber Case 3


40/68

40

Huawei


Questions

What are the major causes resulting in Internet

access failure when LAN upstream is used?

What are the major causes resulting in slow

Internet access when LAN upstream is used?


41/68

41

Huawei


Course Contents






42/68

42

Huawei



1 Internet Access Failure

2 Slow Internet Access


43/68

43

Huawei


Categories of Internet Access Failures

Whether data


Whether the system,

ESM and ports are normal

Whether theopposite equipment

works normally

Whether subscriber


Analyze Internet



44/68

44

Huawei


Checking Running of Upper Layer Equipment

Check the upper layer equipment

A faulty upper layer equipment usually affects the users greatly,

that is, users on one or multiple MA5300 cannot access the

Internet. In this case, check the upper layer equipment at the

following aspects:

Working states and port states of the upper layer equipment that is

connected with MA5300

Transmission between the MA5300 and upper layer equipment

States of the upper layer BAS, router and switch. You can test the

address of the upper layer equipment by PING or TRACERT, so as to

locate the problems.



45/68

45

Huawei



Equipment Test Method

Test method

If there is an idle port on the main control board, allocate the

upstream and idle port (hereinafter referred to as testport) to

the same VLAN. Then, connect the PC to the test port, and begin

the test. If the PC can be connected to the Internet, it indicates that no faults

occur to the upper layer equipment and ESM. You should focus on

checking MA5300.

Set the PC address and subscriber address to the same segment, andexecute the PING commands. If the command is executed successfully,

it indicates that no faults occur to MA5300. In this case, you should

focus on checking the settings of the upper layer equipment.


46/68

46

Huawei


Checking Running of System and ESM

Check the working states of the system, ESM and ports

A faulty MA5300 or a faulty ESM affects all subscribers on the

MA5300. In this case, check the version configuration, main

control board states and network cable length of MA5300.

Check whether ESM work normally, and versions of the service board,

main control board and ISU are matched.

Check whether the LINK LED is normal on the ESM, and check whether

entries in the MAC table are set correctly.

Check whether the concatenation and upstream network cables of MA5300

are not longer than five meters, but too short network cables may result in

many CRC errors or even blocked service on the interface.


47/68

47

Huawei


Checking Data Configuration

Check data configurations

Incorrect data configuration usually happens in new deployment or

addition of new users. When problems occur to an online

equipment, focus on checking these two items.

Check whether the information of the upper layer equipment of MA5300

is set correctly, such as the accounts, VLANs and routes.

Check whether the PVC of the ADSL subscriber port and the RTU on the

subscriber side are set correctly.

Check whether the encapsulation type of ADSL ports are correct, forexample, if the ADSL port is Auto type by default, and coordinates with

the MODEM of the Auto type, subscribers may fail to access the Internet.


48/68

48

Huawei


Checking Subscriber Side Settings

Check subscriber side settings

When only some subscribers have difficulties in Internet access,

focus on checking the configurations and states of these subscriber

sides.

Check the settings of the equipments on the subscriber side such as therouter and switch.

Check the network adapters and connections.

For a dialup subscriber, check the installation and settings of the dialup

software. The Enternet 300 or Enternet 500 software is recommended.

Check the settings of the subscriber address, gateway, DNS and route

table entry.

Check whether the PC is infected by viruses.


49/68

49

Huawei


The subscriber name and password for PPPOE dialup are correct, but

fail to be authenticated by the server.

[Phenomenon] ADSL subscribers are authenticated with PPOE for Internet accessing.

The correct subscriber name and password are input, but the dialup program returns

the authentication failure alarm. Dial up again after one hour, and the authentication is

successful. The used PPPOE dialup software is ENTERNET300.[Alarm] The dialup software returns the alarm authenticationfail.

[Analysis]

Because the Radius Server restricts the number of the concurrent subscribers with the

same account, and sets the time for checking the accounts that are disconnected and

exit abnormally. In this case, the Radius Server restricts the number of the concurrent

users of this account, and sets a longer time for check and update, so the server still

keeps the access information of this account after the subscriber side was abnormally

terminated due to the computer breakdown or other reasons.

Internet Access Failure Case 1


50/68

50

Huawei


When the subscriber dials up again, the server considers an illegal access (user

number>1) , rejects the access request, and returns an alarm as it already has the

account use information. After the preset update time, the server terminates the

access process of this account when it does not receive any access information, so

the later dialup request is accepted and authenticated.

[Handling Process]

Terminate the access process of the account manually on the Radius Server.

Increase the number of concurrent account users in the account settings on

the Radius Server.

Shorten the user information update time on the Radius Server, for example,

changing it to 5 minutes.



51/68

51

Huawei


An abnormal DNS server results in Internet access failure of ADSL

subscribers.

[Phenomenon] The ADSL subscriber complained about Internet access

failure through his computer or even through another computer.

[Analysis] This problem is caused by the office DNS server, but the

DNS server cannot be pinged only by disconnecting it. In this case,

compare its settings with other computers to find the real cause. If the

domain name cannot be directly input, input the IP address (not through

the DNS).



52/68

52

Huawei


[Handling Process] Observe whether the RTU is deactivated, and you can find that the MODEM

works normally.

Ping the gateway and DNS server. Both operations are successful.

Change a computer, but the problem still exists.

Directly input the IP address, and you can find that accessing the Internet is

successful.

Then, you can sure that the DNS server is faulty.

The Internet is accessed successfully from other IP addresses successfully.

Then, compare the DNS data, and find that there are backup data on other

DNS servers. The Internet is accessed successfully even by changing to

another DNS server. Then, the problem is solved.



53/68

53

Huawei


Categories of Slow Internet Access

Whether the upperlayer equipments are

congested

Whether equipments


Whether ports are

connected to upper layer

equipments normally

Whether ESM

ports are congested

Analyze slow

Internet access causes


54/68

54

Huawei


Check Congestion among Upper Layer Equipments


equipments


equipments may result in slow Internet access, for example,

Internet accessing slows down on MA5300 after some time orwith more and more subscribers.

Test method: Know networking conditions, ping the address of

the interfaces of upper layer equipments orderly, observe the

packet loss ratio and delay, and compare with the values in

normal cases to find whether faults occur to the upper layer

equipments.

Ch ki Fl C l S i


55/68

55

Huawei


Checking Flow Control Settings

Check whether upper layer equipments and MA5300 control

the flows of subscribers.

Under flow control, the downloading ratios of subscribers vary

unnoticeably and usually the same. There are some common flowcontrol modes:

Limit port rates for ADSL subscribers

Control flows by upper layer BAS according to accounts, ports and

VLANs

Ch ki O ti f S t d ESM


56/68

56

Huawei


Checking Operation of System and ESM

Check connections among the system, ESM and upper layerequipment.

If ESM uses FE upstream, query whether the ports on ESM board

work in 100M full duplex. If not, set 100M full duplex forcibly.

Otherwise, Internet accessing may slow down in case of great traffic.

Check whether the concatenation and upstream network cables of

MA5300 are not longer than five meters, but too short network cables

may result in many CRC errors or even blocked service on the

interface.

Query the system alarm messages to find whether there are related

alarms.

Ch ki C ti ESM P t


57/68

57

Huawei


Checking Congestions on ESM Ports

Check whether the ports on ESM are congested.

The MUX VLAN or Smart VLAN is recommended. Otherwise, subscriber lines must

be congested when a great amount of broadcast packets, multicast packets or

unknown unicast packets are sent to the subscriber, thereby resulting in slow Internet

access. In this case, monitor the traffic over lines on the subscriber side through

Sniffer to find out the congestion causes.

If there is an idle port on the main control board, allocate the upstream port and idle

port to the same VLAN. Then, connect the PC to the test port to test the Internet

accessing rate, and compare it with that of the XDSL subscriber.

For the ADSL subscriber using the ESM upstream, add the subscriber bandwidth,

and check whether the faults are gradually removed to judge whether the subscriber

line is congested.

When the ports are congested when many subscribers go through multiple FE

upstream of ESM, convergent multiple ports on the ESM to share loads and add valid

bandwidth.

Sl I t t A C 1


58/68

58

Huawei


Too many broadcast packets result in a high CPU usage of MA5300 main controlboard, unstable Internet access and a high packet loss ratio.

[Phenomenon] ISN8850-MA5300_A-MA5300_BThe CPU usage on the main

control board of MA5300_A is rather high, and its concatenated MA5300_B also

undergoes a high CPU usage reaching 70%. The subscribers for MA5300_B

cannot access the Internet, gain an unstable access or gain a high packet loss

ratio. Networking: ISN8850-MA5300_A-MA5300_B

[Handling]

Check whether there are multiple layer 3 interfaces. Check the data configurations of

two MA5300, and find that only one layer 3 interface is configured.

Check the upstream interface and concatenated interface on MA5300_A, and find

that broadcast packets undergo a great growth rapidly. It is necessary to find out the

equipment that send the broadcast packets.

Slow Internet Access Case 1

Sl I t t A C 1


59/68

59

Huawei


MA5300_A concatenated interface:

MA5300(config)#show interface ethernet 7/2/0

...........................................

74564 packets output, 1274 packets/sec, 98396 bytes/sec

5730844 bytes, 1 multicasts, 15 broadcasts, 0 pauses

76685 packets input, 1309 packets/sec, 134346 bytes/sec



..................................






Sl I t t A C 1


60/68

60

Huawei


MA5300_A upstream interface:


...................................................





Check the input/output the receiving & transmitting broadcast packets, and findthat:

The output broadcast packets grow rapidly on the upstream interface 7/1/0:



The input broadcast packets grow rapidly on the upstream interface 7/2/0:



This indicates that broadcast packets are sent from the interface 7/2/0,

estimating that some subscriber under the frame sends a great amount of

broadcast.


Sl I t t A C 1


61/68

61

Huawei


Set the interface of the MA5300_B that is connected to the slave frame to

shutdown first and then no shutdown. Then, you can find that the CPU

usage of MA5300_A recovers to normal.

Capture the broadcast packets with the capture software to find out the MAC

that sends the packets. Then, find the corresponding subscriber ports, removeviruses on the subscriber machine, and the problem is solved.

[Analysis]

This problem is resulted from too many broadcast packets. Because

broadcast packets should be submitted to CPU for processing, it causes a

high CPU usage and failure in processing normal service packets.


Q ti


62/68

62

Huawei


Questions

What are methods adopted for testing the

upper layer equipment in case of Internet

access failure or slow Internet access from

MA5300?

Why is MUX VLAN or Smart VLAN rather

than alternate VLAN required for deployment

and maintenance?

Course Contents


63/68

63

Huawei


Course Contents







64/68

64

Huawei



1 Internet Access Failure

2 Slow Internet Access



65/68

65

Huawei



Whether data


Whether the

system, SCU and

ports are normal

Whether theopposite equipment

works normally

Whether subscriber


Analyze Internet




66/68

66

Huawei



Whether upperlayer equipments

are congested

Whether equipments


Whether ports are

connected to upper layer

equipments normally

Whether SCU

ports are congested

Analyze slowInternet access

causes

MA5600 Troubleshooting Flow Description


67/68

67

Huawei


MA5600 Troubleshooting Flow Description

The troubleshooting flow of MA5600 is similar to that of

MA5300. For details, please refer to MA5300 Troubleshooting

Flow.

MUX VLAN Configuration


68/68

Huawei

MUX VLAN Configuration

Add Multiple Ports to Different MUX VLAN

Add all ADSL and SHDSL ports to MUX VLANs, with the first

port corresponding to VLAN 2.

MA5600(config)#multi-service-port from-vlan 2 board 0-15 vpi0 vci 35 rx-cttr 2 tx-cttr 2

Documents

01-DSLAM Troubleshooting Training ISSUE1.0