Preface - Experience, Issue134(Data Products).pdf · Preface Maintenance Experience Editorial Committee Maintenance Experience Newsroom ... that EAPS takes less time than 50ms to

PrefaceMaintenance ExperienceEditorial Committee

Maintenance ExperienceNewsroom

Address: ZTE Plaza, Keji Road South, Hi-Tech

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Director: Qiu Weizhao

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Editors:Jiang Guobing, Zhang Shoukui, Wu Feng,

Yuan Yufeng, Tang Hongxuan, Chen Huachun,

Li Gangyi, Gu Yu, Song Jianbo, Tian Jinhua,

Du Jianli, Qu Ruizheng, Liu Xianmin, Wang

Zhaozheng, L iu Wenjun, Lei Kun, Wang

Tiancheng, Cai Hongming, Wang Yapping

Technical Senior Editors:Hu Jia, Bai Jianwen

Executive Editor:Zhang Fan

Maintenance Experience Editor CommitteeZTE CorporationOctober, 2008

In this issue of ZTE's "Maintenance Experience", we continue to pass on various field reports and resolutions that are gathered by ZTE engineers and technicians around the world.

The content presented in this issue is as below: One Special Document Seven Maintenance Cases of ZTE's Data Products

Have you examined your service polices and procedures lately? Are you confident that your people are using all the tools at their disposal? Are they trained to analyze each issue in a logical manner that provides for less downtime and maximum customer service? A close look at the cases reveals how to isolate suspected faulty or mis-configured equipment, and how to solve a problem step by step, etc. As success in commissioning and service is usually a mix of both discovery and analysis, we consider using this type of approach as an example of successful troubleshooting investigations.

While corporate leaders maintain and grow plans for expansion, ZTE employees in all regions carry out with individual efforts towards internationalization of the company. Momentum continues to be built, in all levels, from office interns to veteran engineers, who work together to bring global focus into their daily work.

If you would like to subscribe to this magazine (electronic version) or review additional articles and relevant technical materials concerning ZTE products, please visit the technical support website of ZTE Corporation (http://ensupport.zte.com.cn).

If you have any ideas and suggestions or want to offer your contributions, you can contact us at any time via the following email: [email protected].

Thank you for making ZTE a part of your telecom experience!

Maintenance ExperienceBimonthly for Data Products

No.55 Issue 134, October 2008

Contents

ZESR Configuration 2

Master Node Remote Login on ZESR Ring Network 17

ZESR Millisecond Convergence 20

Double Independent Main Rings on ZESR 21

Address Superposition 22

Switch CPU Utilization Ratio Abnormity 24

Lighting Stroke Damage on Broadband Device 26

A Tip of Batch Pasting on Hyper Terminal and SecureCRT 27

October 2008 Issue 134

Maintenance Experience2

ZESR Configuration⊙ Zhu Changfei / ZTE Corporation

1 ZESR PrincipleZTE Ethernet Smart Ring (ZESR) is a

technique of Ethernet ring based on EAPS

protocol (RFC3619). ZESR allows network

administrators to create Ethernet rings.

It is like Fiber Distributed Data Interface

(FDDI) or SONET/SDH ring. When a link or a

node malfunction occurs, the switches which are

configured ZESR can recover within 50ms. The

exact time for recovering depends on the number

of nodes in the ring.

Ethernet Automatic Protection Switching

(EAPS) is a solution introduced by Extreme

Networks Corporation for Layer-2 loop problem.

Comparing with STP, the advantage of EAPS is

that EAPS takes less time than 50ms to hand

over the l ink and to resolve the problem of

communication when a link is down on the ring.

ZTE introduces ZESR, which is a technique

that has additional information based on EAPS

protocol. ZESR has the advantage of EAPS, that

is, the fast Layer-2 constringency capability. In

addition, ZESR has the networking capability in

complicated ring environments.

As shown in Figure 1, in the Ethernet ring, S1

is a master node, and other switches are transit

Key words:ZESR, Ethernet ring, EAPS

Figure 1. ZESR Principle

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3Data Products

nodes. On the master node, one port is primary

and the other is secondary.

In the process of initialization, the secondary

port is blocked to prevent loop. When a transit

node finds that fault occurs in an adjacent link,

it will send a Link Down message to the master

node.

When the master node receives the Link

Down message, it clears FDB table and opens

secondary port to send RING-DOWN-FLUSH-FDB

messages to the transit nodes. The transit nodes

clear their FDB tables. After that, the switches learn

addresses again in a common way.

To prevent the master node from missing the

Link Down message, the master node sends

Health frames from primary port periodically. The

Health frame goes along the ring and it is received

by the master node on the secondary port.

If the secondary port does not receive the

frame within a designated time, the master

node considers that a link on the ring is broken.

Therefore, the master node takes action as if it

receives a Link Down message.

After that, master node still sends Health

frames periodically. If the Health frame is received

on the secondary port, the master node considers

that the link has recovered. Then the master node

clears the FDB table and sends RING-UP-FLUSH-

FDB messages to transit nodes again.

Before the master node f inds that l ink

recovers, the transit node adjacent to the link

finds that link recovers first. If the transit node

enables the corresponding port immediately, a

loop will generate. To avoid this situation, when

the transit node adjacent to the link finds that link

recovers, it does not enable the corresponding port

immediately. This state is called preforwarding.

This state is kept until the transit node receives the

RING-UP-FLUSH-FDB message from the master

node.

All Health frames, Link-Down messages, RING-

DOWN-FLUSH-FDB messages and RING-UP-

FLUSH-FDB messages are transmitted in

an independent control VLAN.

2 Basic Terms

2.1 ZESR Domain

A ZESR domain comprises a group of

switches with the same domain ID, control

VLAN and different protected VLANs. The

switches in the group connect to each

other, as shown in Figure 2. It is allowed to

be one or multiple ZESR domains on the

same physical ring. Each ZESR domain

can define the master node, transit nodes

and edge node of its own.

A ZESR domain may comprise one or

multiple rings connecting with each other.

A ring may include one or multiple ZESR

domains.

2.2 ZESR Ring

A physical ZESR ring is corresponding

to a ring Ethernet topology. When a ZESR

domain comprises multiple ZESR rings

that connect with each other, one of the

rings is the main ring of Level 0. Other

rings are segment links of different levels

on the main ring. When a ZESR domain

includes only one ring, the ring can be

configured as the main ring.

Figure 2. ZESR Domain



2.3 Control VLAN

Protocol messages of ZESR are

transmitted in the control VLAN. Each

ZESR domain has a control VLAN.

2.4 Protected VLAN

Protected VLAN is also a service

VLAN. There are mult iple protected

VLANs in each ZESR domain. The

messages of user services are transmitted

in the protected VLANs. Layer-2 service

protection of service traffic is implemented

through pruning.

2.5 Master Node

Master node is the policy and control

node on a ZESR ring. There is a master

node on the main ring and each segment

link of different levels. These master nodes

control the main ring and segment links.

2.6 Transit Node

Except the master node on a ZESR

ring, other nodes are transit nodes. They

help the master node to detect the status

of ZESR ring and hand over the services under the

control of the master node.

2.7 Edge Node

On a ZESR ring, the node that connects with

more than two segment links is called edge node.

On the segment link with higher level, the edge

node is a master node or a transit node (including

two ports). On the segment link with lower level,

the edge node is an edge assistant node or an

edge control node (including only one port).

2.8 Edge Assistant Node

An edge assistant node is a transit node that

only has one port on the corresponding segment

link. It helps the master node or edge control node

on the segment link to detect the status of ZESR

ring and hand over the services. There mast be

one or two edge assistant nodes on different

segment links, but there may be no edge control

node. When there is only one edge assistant node,

the master node should be the edge control node.

2.9 Edge Control Node

An edge control node is the master node that

only has one port on the corresponding segment

link. It carries out policy and control on the

corresponding segment link together with the other

edge assistant node.

As shown in Figure 3, switches S1~S8 are

in a ZESR domain. Switches S1, S9 and S10

are in another ZESR domain. The two domains

are tangent on node S1 and they use the same

protected VLAN.

In ZESR domain 1, there is a main ring and

three segment links. The main ring comprises S1,

S2, S3 and S4. S2 acts as master node and others

are transit nodes.

Level 1-Seg 1 comprises S3, S4, S5 and S6.

S5 acts as master node. S6 acts as transit node

and others are edge assistant nodes.

Level 1-Seg 2 comprises S3, S4 and S8. Figure 3. ZESR Network Topology

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5Data Products

S3 acts as edge control node. S4 acts as edge

assistant node and S8 acts as transit node.

Level 2-Seg 1 comprises S5, S6 and S7. S7

acts as master node and others are edge assistant

nodes.

2.10 Link Down Message

When a transit node finds that fault occurs on

an adjacent link, it will send a Link Down message

to the master node. After the master node receives

the Link Down message, it clears FDB table and

opens secondary port to send RING-DOWN-

FLUSH-FDB messages to the transit nodes. The

transit nodes clear their FDB tables. After that, the

switches learn addresses again in a common way.

2.11 Healthy Frame & Healthtime & Failtime

When the ring works normally, the master node

sends Health frames from primary port periodically.

The interval to send the frames is healthtime. When

the master node receives the Health frame on its

secondary port, it knows that the ring is working

normally, and then it refreshes its timer. The time

on the timer is failtime. Once the secondary port

does not receive the frame within failtime, the

master node considers that a link on the ring is

broken. Therefore, the master node takes action

as if it has received a Link Down message. The

failtime should be configured at least three times of

healthtime.

2.12 RING-DOWN-FLUSH-FDB

When the master node begins to hand over

the ring, it clears its FDB table and enables its

secondary port. Meanwhile, it sends RING-DOWN-

FLUSH-FDB messages to the transit nodes to

inform them to clear FDB tables and learn MAC

addresses again.

2.13 RING-UP-FLUSH-FDB

After the link fault occurs, if the master receives

Health frame on the secondary port again, the

master node considers that the link has

recovered. Then the master node clears

its FDB table and disables the secondary

port. It also sends RING-UP-FLUSH-FDB

messages to transit nodes to inform them

to clear their FDB tables.

2.14 Pre-Forwarding & preforwardtime

The transit node adjacent to the fault

link finds that link recovers earlier than

the master node. To avoid loop, the transit

node does not enable the corresponded

port immediately. Instead, it forwards

service data through its port until the

master node receives RING-UP-FLUSH-

FDB message.

However, if the transit node does not

receive the message indicating that master

node has received the RING-UP-FLUSH-

FDB message within a certain time period;

the transit node will enable its port. The

waiting time is called preforwardtime.

During the preforwardtime, the transit node

is in Pre-Forwarding state.

2.15 Pre-Up & preupdelaytime

To avoid loops caused by continual

link changes, master node does not block

its secondary port immediately when it

receives Health frame send by itself. It

waits for a duration time until it is certain

that the link is steady. The duration time

is called preupdelaytime. During the

preupdelaytime, the master node is in Pre-

Up state.

3 ZESR Detailed Introduction

3.1 Nonzero Level Segment Link

For complicated network, hierarchical

ZESR technique is introduced. When there



is no link down on main ring or segment

that is one level higher than the segment

link, ZESR can run normally on the certain

segment link. That is, the status of the last

ring is shielded to the next level segment

link.

As shown in Figure 4, level 1-Seg 1

comprises S3, S4, S5 and S6. S3 and S4

are edge assistant nodes. S5 is a master

node. Level 1-Seg 1 always considers that

the main ring which S3 and S4 are on is

connected. When the links on level 1-Seg

1 are Up, S5 blocks its secondary port.

When there is a link down on level 1-Seg 1,

S5 will enable its secondary port.

However, if the link between S3 and S4 is

down, S5 will not enable its secondary port. It is

because level 1-Seg 1 always considers that the

main ring is connected. The information that the

link between edge nodes is down is only sent to

the main ring.

3.2 Master Node on Main Ring

There is a master node on the main ring of a

ZESR domain. As shown in Figure 3, S2 is the

master node that initiates Polling mechanism, and it

is also the decision-maker that takes corresponding

actions after the topology is changed.

The master node sends Hello messages from

its primary port periodically. The messages are

transmitted along the transit nodes, as shown in

Figure 5. If the master node receives the Hello

messages on its secondary port and does not

receive Link Down messages, the links are normal.

Otherwise, the master node considers that a

certain link is down.

The master node on main ring has two states:

ring complete state and ring failed state.● Ring Complete State

In this state, there is no link down on the main

ring. The master node disables its secondary

port to forward service data in corresponding

protected VLAN. This prevents storm caused by

loop. The master node sends Hello messages

from its primary port periodically and receives

the messages on its secondary port.● Ring Failed State

When certain link on the ring is down, and when

the master node receives the link down event

or the master node finds that Hello message

is overtime, the master node is in ring failed

state. At this time, the master node enables

its secondary port to forward service data in

corresponding protected VLAN. As the topology

of the ring is changed, the master node sends

Flush-FDB messages on primary port and

secondary port to the transit nodes to inform

Figure 4. Nonzero Level Segment Link

Figure 5. Master Node on Main Ring

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7Data Products

them to clear their FDB tables that are related

to protected VLAN.

The states changes are shown in Figure 6.

3.3 Master Node on Segment Link

There is a master node (master node of the

segment link) on each segment link. As shown

in Figure 3, S8 is the master that initiates Polling

mechanism. It is also the decision-maker that

takes corresponding actions after the topology is

changed.

The master node sends Hello messages from

its primary port and secondary port periodically.

The messages are transmitted along the transit

nodes. At last, the Hello messages arrive at the

edge assistant node. The edge assistant node is

responsible for sending the Hello messages back

to the master node through its access ports, as

shown in Figure 7. If the master node receives the

Hello messages on its primary port and secondary

port, and it does not receive Link Down messages,

the links are normal. Otherwise, if the master does

not receive Hello messages on either of the two

ports, the master node considers that a certain link

is down.

The master node on segment link has two

states: Seg complete state and Seg failed state.● Seg Complete State

In this state, there is no link down on the

segment link. The master node disables its

secondary port to forward service data in

corresponding protected VLAN. This prevents

storm caused by loop. The master node sends

Hello messages from its primary port and

secondary port periodically. The messages are

transmitted along the transit nodes. At last, the

Hello messages arrive at the edge assistant

node. The edge assistant node sends the Hello

messages back to the master node through its

access ports. The Hello messages return to

master node on the primary port and secondary

port.

● Seg Failed State

When certain link on the segment link

is down, and when the master node

receives the link down event or the

master node finds that Hello message

is overtime, the master node is in Seg

Failed State. At this time, the master

node enables its secondary port to

forward service data in corresponding

protected VLAN. As the topology of the

Figure 6. State Changes

Figure 7. Hello Messages on Segment Link



nodes on main ring or segment link for turning

to Complete state, the transit node transfers to

forwarding state automatically.

3.5 Edge Assistant Node

An edge assistant node is a transit node that

only has one port accessed to segment link. It

is responsible for monitoring the state of master

node on segment link. When the edge assistant

node finds it is out of touch with the master node, it

becomes the temporary master and sends RING-

DOWN-FLUSH-FDB messages, indicating that the

segment link is in Failed state.

Besides the three states of common transit

node, edge assistant node has another two states.● Master-Up state

Edge assistant node receives Hello messages

from master node and sends echo messages

on the access port periodically. If the timer is

not overtime, the edge assistant node is in

Master-Up state.● Master-Down state

When edge assistant node does not receive

Hello messages from master node on the

access port within designated time, or when

edge assistant node receives events about link

intermitting and port is in Links-Down state, the

edge assistant node is in Master-Down state.

Once it turns to Master-Down from Master-Up,

if the segment link is in Complete state, the

link will turn to Failed state. Meanwhile, edge

assistant node sends RING-DOWN-FLUSH-

FDB messages to the nodes on segment link

and upper level.

3.6 Primary Port and Secondary Port

On a master node or a transit node (except

edge assistant node), one of the two ports

accessing to ZESR ring is primary port, the other is

secondary port. The role of the ports is configured

by users. Primary port and secondary port have

different functions.

segment link is changed, the master

node sends Flush-FDB messages on

primary port and secondary port to the

transit nodes on the segment link and

corresponding nodes of upper level to

inform them to clear their FDB tables

that are related to protected VLAN.

For edge control node, it is similar with

the master node on segment link. The

difference is that the edge control sends

Hello messages only on its access ports

and it only monitors the link at its access

port side.

3.4 Transit Node

A transit node detects the state of

ZESR links connecting to itself directly. It

informs the master node and edge nodes

of the link changes.

Transit node has the following states.● Links-Up state

I n n o r m a l s i t u a t i o n , t h e p o r t s

connecting to the ZESR link are in

Links-Up state.● Links-Down state

When transit node is in Links-Down

state, the main ring (or segment link) is in

Failed state. At least one of the two ports

that connect to the ZESR link is DOWN. ● Pre-Forwarding state

This is an instantaneous state before

the l ink recovers. When a transit

node is in this state, the port that was

down becomes up and the service

forwarding function of protected VLAN

is disabled. When the main ring (or

segment link) is in Complete state, the

transit node can forward service data.

ZESR provides a backup mechanism

to recover the temporary-blocked port

and trigger state switch. If the transit

node does not receive messages from

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9Data Products

Master node on main ring sends loop-state

detection message from its primary port. If master

node receives the message on its secondary port,

the ring is complete and the secondary port should

be blocked to prevent a loop. If master node does

not receive the loop-state detection message

within designated time, there is fault on the main

ring. At this time, the secondary port should be

enabled to ensure smooth communication. When

the secondary port is blocked, master node does

not forward flush messages that it receives from

segment links of different levels. Otherwise, it

forwards these flush messages.

Master node on segment link sends loop-

state detection message from its primary port

and secondary port. If it receives the message

on its primary port and secondary port, the ring

is complete and the secondary port should be

blocked to prevent a loop. If master node does not

receive the loop-state detection message within

designated time, there is fault on the main ring. At

this time, the secondary port should be enabled to

ensure smooth communication.

The primary port and secondary port on a

transit node have the same functions. The role of

the ports is also configured by users.

3.7 Access Port

Only one port on an edge assistant port (edge

control port) is on the segment link. This port is

called access port. The port is responsible for

receiving (sending) Hello messages from master

node on segment link, receiving intermitting

events and flush messages. Edge assistant

node judges the state of master node on the

segment link according to the Hello messages and

intermitting events that it receives. Besides, it also

helps to maintain flush messages. No matter the

flush messages are received on access port or

generated by the segment link the node locates,

the messages are sent to corresponding ports on

upper level segment link or the main ring to hand

over service.

3.8 ZESR Convergence Speed

The ZESR convergence speed is

related to the following factors.● Refreshing speed and capacity of MAC

address table● The number of ports that need to

refresh address table● STP handover speed on a port● The number of ports that participate in

STP handover● The number of ZESR domains when

there are multiple domains

4 Configuring ZESRTo conf igure ZESR, perform the

following steps.

1. To configure ZESR protect ion

instance binding, use the fol lowing

command.

ZXR10(config)#zesr ctrl-vlan <vlan-

id> protect-instance <0-16>

This binds the control VLAN to STP

instance that needs protection. The STP

instance is configured in STP module.

2. To configure the role of ZESR main

ring, use the following command.


id> major-level role < master | transit >

<port1> <port2>

This configures the role of ZESR

main ring. For the master node, the first-

configured port is the primary port, and the

second-configured port is the secondary

port. For transit node, the role of the two

ports is the same.

3. To configure the role of master node

on ZESR segment link, use the following

command.


id> level <1-2> role seg <1-4> master



<port1> <port2>

This configures the role of master node

on ZESR segment link. Parameter level <1-2> identifies the level and parameter

seg <1-4> identifies the segmentp. For

the master node, the first-configured

port is the primary port, and the second-

configured port is the secondary port.

Master node sends Hello messages

and detects whether the link is complete

through the secondary port.

4. To configure the role of transit node

on ZESR segment link, use the following

command.


id> level <1-2> role seg <1-4> transit <port1> <port2>

This configures the role of transit node

on ZESR segment link. Parameter level <1-2> identifies the level and parameter

seg <1-4> identifies the segment. For

transit node, the two ports have the same

role and they forward Hello messages.

5. To conf igure the role of edge

assistant node on ZESR segment link, use

the following command.


id> level <1-2> seg <1-4> role edge-assistant <port1>

This configures the role of edge

assistant node on ZESR segment link.

Parameter level <1-2> identifies the level

and parameter seg <1-4> identifies the

segment. Edge assistant sends Hello

echos.

6. To configure the role of edge control

node on ZESR segment link, use the

following command.


id> level <1-2> seg <1-4> role edge-control <port1>

This configures the role of edge control

node on ZESR segment link. Parameter level <1-2> identifies the level and parameter seg <1-4>

identifies the segment. Edge control node sends

Hello messages and detects whether the link is

complete.

7. To configure preforward parameter and

preup parameter of transit node, use the following

command.

ZXR10(config)#zesr ctrl-vlan < vlan-id >

major-level | level <1-2> seg <1-4> preforward <1-600> preup <0-500>

This configures preforward parameter and

preup parameter of transit node. Parameter

preforward <1-600> is the duration of preforward

state, and preup <0-500> is the duration of preup

state. They are in unit of second. The duration of

preforward state should be the same in the whole

domain. The duration preup state is effective on

control node. The requirement is preforward –

preup >=1.

8. To configure hello parameter and fai l

parameter of transit node, use the following

command.

ZXR10(config)#zesr ctrl-vlan < vlan-id >

major-level | level <1-2> seg <1-4> hello <1-6>

fail <3-18>

This configures hello parameter and fail

parameter of transit node. Parameter hello <1-6> is

the interval for sending Hello messages. Parameter

fail <3-18> is the timeout of Hello messages. They

are in unit of second and are effective on control

node. The requirement is hello*3 <=fail.

9. To configure restart-time parameter of ZESR

node, use the following command.

ZXR10(config)#zesr restart-time <30-600>

This configures restart-time parameter of ZESR

node. When line interface card and the rack are

rebooted, ZESR port is blocked within the restart-

time. It is effective on transit node and edge

assistant node, in unit of second.

10. To view ZESR configuration information,

use the following command.

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11Data Products

ZXR10(config)#show zesrThis displays ZESR conf igurat ion. This

command can be used in all modes.

ZXR10(config)#show zesr briefThis displays brief ZESR configuration. This

command can be used in all modes.

5 ZESR Configuration Examples

5.1 Single Ring Configuration Example

Three T64G switches form a ring, as shown

in Figure 8. The ports of the switches are in

VLAN10-20. It is required to break the loop.

Configure gei_1/1 on T64G-1 as the primary port

and gei_1/2 as the secondary port.

Topology like this is used to implement link

backup.

Configuration on T64G-1:

T64G-1#vlan databale

T64G-1(vlan)#vlan 10-20 /*protected

vlan*/

T64G-1(vlan)#vlan 4000 /*control vlan*/

T64G-1(vlan)#exit

T64G-1(config)#interface gei_1/1

T64G-1(config-if)#switchport mode trunk

T64G-1(config-if)#switchport trunk vlan 10-20

T64G-1(config-if)#switchport trunk vlan 4000

T64G-1(config-if)#exit






T64G-1(config)#spanning enable

T 6 4 G - 1 ( c o n f i g ) # s p a n n i n g - t r e e m s t

configuration

T64G-1(config-mstp)#instance 1 vlans 10-20

T64G-1(config)#zesr ctrl-vlan 4000 protect-

instance 1

T64G-1(config)#zesr ctrl-vlan 4000 major-level

role master gei_1/1 gei_1/2



T64G-2(vlan)#vlan 10-20

T64G-2(vlan)#vlan 4000

T64G-2(vlan)#exit


T64G-2(config-if)#switchport mode

trunk

T64G-2(config-if)#switchport trunk vlan

10-20


4000




trunk


10-20


4000



T64G-2(config)#spanning-tree mst

configuration

T64G-2(config-mstp)#instance 1 vlans

10-20

T64G-2(config)#zesr ctrl-vlan 4000

protect-instance 1


major-level role transit gei_1/1 gei_1/2

Configuration on T64G-3 is the same

Figure 8. Single Ring Configuration Example



as that on T64G-2.

Configuration information on T64G-1 is

shown below.

T64G-1 (config)#show zesr

ZESR domain:

ctrl vlan 4000 /* control

VLAN*/

ports gei_1/1(Primary) gei_1/

2(Secondary) /*primary port and

secondary port on master node*/

node type MASTER /*node

type*/

mode standard /*MAC

address learn ing mode, i t i s here

standard*/

ring Up /*current working

state of ring. It can not be up under mis-

configuration*/

switch times 5 /*handover

times of the ring. Link fault occurred and

recovered twice.*/

healthtime: 1ms /*interval for

sending healthy frames*/

failtime: 3ms /*timeout of healthy

frames*/

Brief configuration information on

T64G-1 and T64G-2 is shown below.

T64G-1 (config)#show zesr brief

ctrl-vlan: 4000 protectinstance: 1

level seg role port port

level-state switch-times

major master gei_1/1(P) gei_1/2(S)

up 1



level seg role port port level-state

switch-times

major transit gei_1/1(P) gei_1/2(S)

up 1

5 . 2 S i n g l e R i n g M u l t i p l e I n s t a n c e s Configuration Example

Four T64G switches form a ring, as shown

in Figure 9. The ports of the switches are in

VLAN10-20 and VLAN30-40. It is required to break

the loop and implement load balance. Service

traffic in VLAN 10-20 goes through T64G-1,

T64G-2 and T64G-4. Service traffic in VLAN 30-40

goes through T64G-1, T64G-3 and T64G-4.

To meet the requirements, configure two

MSTP instances, instance 1 and instance 2. Map

VLAN10-20 to instance 1 and map VLAN30-40

to instance 2. VLAN 4000 protects instance 1, in

which gei_1/1 on T64G-1 is configured as primary

port and gei_1/2 as secondary port. VLAN4001

protects instance 2, in which gei_1/2 on T64G-1

is configured as primary port and gei_1/1 as

secondary port.

Topology like this is used to implement load

balance and link backup.




vlan*/


vlan*/

T64G-1(vlan)#vlan 4000-4001 /*control

vlan*/

T64G-1(vlan)#exit



T64G-1(config-if)#switchport trunk vlan 10-20Figure 9. Single Ring Multiple Instances Configuration Example

www.zte.com.cn

13Data Products

Maintenance Materials

4000-4001




configuration


10-20


30-40


protect-instance 1


protect-instance 2





Configuration on T64G-3 and T64G-4

are the same as on T64G-2.


T64G-1 is shown below.

T64G-1 (config)#show zesr b




major master gei_1/1(P) gei_1/

2(S) up 1





1(S) up 1


T64G-2 is shown below.

T64G-2 (config)#show zesr b




major transit gei_1/1(P) gei_1/

2(S) up 1



T64G-1(conf ig- i f )#switchport t runk vlan

4000-4001







4000-4001




configuration




instance 1


instance 2









T64G-2(vlan)#vlan 4000-4001

T64G-2(vlan)#exit






4000-4001











major transit gei_1/1(P) gei_1/

2(S) up 1

5.3 Multi-Level-Ring Configuration Example

Four T64G switches form a ring, as

shown in Figure 10. The ports of the

four switches are in VLAN10-20, ports

of T64G-1, T64G-2 and T64G-4 are also

in VLAN30-40. It is required that there

is no loop in the network and any link

fault should not affect the services in the

network.

To meet the requirements, use VLAN

4000 as the control VLAN of protected

VLAN10-20 and use VLAN 4001 as the

control VLAN of VLAN30-40. Devide the

network into two levels:● T64G-1, T64G-2 and T64G-4 are in

major-level (level 0), and T64G-1 is the

master node.● T64G-2, T64G-3 and T64G-4 are in

level-1 seg-1, and T64G-2 is the edge

control node.

Configure instance 1 on the four

swi tches, and map VLAN 10-20 to

instance 1. Configure instance 2 on

T64G-1, T64G-2 and T64G-4, and map

VLAN30-40 to instance 2. Configure VLAN 4000

to protect instance 1 and VLAN 4001 to protect

instance 2.





T64G-1(vlan)#vlan 4000-4001 /*control

VLAN*/

T64G-1(vlan)#exit






4000-4001







4000-4001




configuration




instance 1


instance 2









T64G-2(vlan)#vlan 4000-4001Figure 9. Single Ring Multiple Instances Configuration Example

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15Data Products

T64G-2(vlan)#exit






4000-4001












4000-4001




configuration




instance 1


instance 2


role transit gei_1/1 gei_1/3

T64G-2(config)#zesr ctrl-vlan 4000 level 1 seg

1 role edge-control gei_1/2


role transit gei_1/1 gei_1/3

Configuration on T64G-3



T64G-3(vlan)#vlan 4000

T64G-3(vlan)#exit




10-20


4000




trunk


10-20


50-60


4000




configuration


10-20


protect-instance 1


level 1 seg 1 role transit gei_1/1 gei_1/2

Configuration on T64G-4 is similar

with that of T64G-2. The difference is

that T64G-4 is an edge assistant node

instead of an edge control node. The

corresponding command is changed, as

shown below.


level 1 seg 1 role edge-a gei_1/2

Brief configuration information of the

four switches is shown below.






2(S) up 1







level seg role port port level-

state switch-times

master transit gei_1/1(P) gei_1/2(S)

up 1

1 1 edge(A)gei_1/3 up

1



state switch-times

master transit gei_1/1(P) gei_1/3(S)

up 1




state switch-times

1 1 transit gei_1/1(P) gei_1/2(S)

up 1 ■



1(S) up 1





master transit gei_1/1(P) gei_1/

3(S) up 1

1 1 e d g e ( C ) g e i _ 1 / 2

up 1




master transit gei_1/1(P) gei_1/

3(S) up 1

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17Data Products

Master Node Remote Login on ZESR Ring Network⊙Yang Fei / ZTE Corporation

Key words:ZESR, Primary, management VLAN, Telnet

Network TopologyAs shown in Figure 1, three T160G devices

construct ZESR ring network, and they act as HL,

XDJ and NFHY node respectively.

The device T160G on NFHY node is the

MASTER node, and the other two T160G are

Transit node. The port gei_4/10 acts as primary

port, gei_4/12 acts as Secondary port.

The service VLAN are 1~4093, which are

configured on instance 1 of MSTP. VLAN 4094 is

the management VLAN of ZESR ring network.

Malfunction SituationFirstly, engineer accessed XDJ into Internet

network.

Secondly, engineer accessed xgei_6/1 of

HL into xgei_6/1 of XDJ. Gei_4/12 of NFHY was

accessed into gei_3/23 of XDJ.

It was successfully to log on to these three

node devices remotely.

At last, engineer connected the port gei_2/24 of

HL to gei_4/10 of NFHY. The physical ring network

structure of ZESR was completely.

When connecting ports of HL- T160G and

NFHY-T160G, it was failed to log on to NFHY-

T160G remotely through Internet or from XDJ-

T160G.

Figure 1. Network Topology

Malfunction Analysis To find out the problem, the engineers

took the following steps.

1. The engineers logged into the

NFHY-T160G to view the configuration.

ZESR configuration is shown below.

spanning-tree enable

spanning-tree mst configuration

instance 1 vlan 1-4093

interface vlan 22



i p a d d r e s s 1 9 2 . 1 6 8 . 8 1 . 4 2

255.255.255.252

interface gei_4/10

switchport mode hybrid

switchport hybrid vlan 3000-4000 tag

switchport hybrid vlan 4094 tag

switchport qinq normal

interface gei_4/12






ip route 0.0.0.0 0.0.0.0 192.168.81.41

zesr ctrl-vlan 4094 protect-instance 1

zesr ctrl-vlan 4094 major-level role

master gei_4/10 gei_4/12

The ZESR configuration of XDJ-T160G

is shown below.




interface vlan 2

i p a d d r e s s 1 9 2 . 1 6 8 . 8 1 . 3 4

255.255.255.252

interface vlan 21

i p a d d r e s s 1 9 2 . 1 6 8 . 8 1 . 3 7

255.255.255.252

interface vlan 22

i p a d d r e s s 1 9 2 . 1 6 8 . 8 1 . 4 1

255.255.255.252

interface gei_3/23

negotiation auto






interface gei_3/24

description TO_Cisco_12016_3/4

no negotiation auto

switchport mode trunk

switchport trunk native vlan 2

switchport trunk vlan 2


interface xgei_6/1






ip route 0.0.0.0 0.0.0.0 192.168.81.33


zesr ctrl-vlan 4094 major-level role transit

xgei_6/1 gei_3/23

The ZESR configuration of HL-T160G is shown

below.




interface vlan 21

ip address 192.168.81.38 255.255.255.252

interface gei_2/24

negotiation auto





interface xgei_6/1

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19Data Products

6 . The eng ineers examined the

configuration of Primary and Secondary port

on T160G on NFHY and the configuration

of port interconnecting to HL-T160G.

They found that NFHY-T160G device was

MASTER node, the port gei_4/10 was

Primary port, and the port gei_4/12 was

Secondary port. The port gei_4/12 blocked

the service of VLAN 22 (management vlan).

Although the port gei4_10 was not blocked

by ZESR, the VLAN was not configured to

transparently transmit network management

packets on the port gei_4/10. Accordingly,

NFHY-T160G device could not be remotely

logged.

SolutionThe engineer configured VLAN 22

on the port gei_4/10 on NFHY-T160G,

gei_2/24 on HL-T160G and xgei_6/1 on

XDJ-T160G for transparent transmission.

The problem was solved.

Detailed configurations are shown

below.● XDJ-T160G

interface gei_3/23



interface xgei_6/1


switchport hybrid vlan 22 tag● HL-T160G

interface xgei_6/1



interface gei_2/24


switchport hybrid vlan 22 tag● NFHY-T160G

interface gei_4/10


switchport hybrid vlan 22 tag ■






ip route 0.0.0.0 0.0.0.0 192.168.81.37


zesr ctrl-vlan 4094 major-level role transit

xgei_6/1 gei_2/24

2. The engineers logged into the XDJ- T160G

to view the alarm information, and they found that

there was no alarm.

3. The engineers viewed ZESR ring network

working status on XDJ- T160G by using the

command show zesr brief.

XDJ#show zesr brief


level seg role port port level-state

switch-times

major transit x gei_6/1 gei_3/23 up 1

It proved that the working status of ZESR ring

network was UP, the interconnection port was

normal UP. When NFHY- T160G could not be

remotely logged, its interconnection port was UP.

4. The engineers disconnected the link between

HL-T160G and NFHY-T160G, and then remotely

logged into NFHY-T160G to view the alarm

information. They found that there was no alarm

information except an alarm. This alarm showed

ZESR ring network UP/DOWN because of the port

UP/DOWN. It proved that the device on NFHY was

normal.

5. The engineers checked the management

address and the related configuration on device.

They found that the network management packets

were transparently transmitted by NFHY-T160G

to XDJ-T160G. The engineers doubted that the

port was stopped to forward after the ring network

constructing.



ZESR Millisecond Convergence⊙ Zhang Fan / ZTE Corporation

Network TopologyAs shown in Figure 1, T160G-2,

T160G-3 and T160G-4, T160G-5 construct

a ring network and run ZESR protocol.

T160G-5 acts as MASTER node, other

switches act as TRANSIT node. gei_1/1 of

MASTER node is the master port, gei_1/2

is the slave port. The slave port gei_1/2 is

blocked to prevent loop.

Malfunction SituationThe ports of T160G-1, T160G-2 and

T160G-3, T160G-4 and T160G-5, T160G-6

belong to VLAN 10. L3 address is enabled

on each switch.

Eng ineer d isconnected the l ink

between T160G-2 and T160G-5, and

the ring was handed over. The following

situations appear in the transient process

of disconnected ring,● When engineer pinged T160G-1 to

T160G-6, the packet was not lost.● When engineer pinged T160G-3 to T160G-4,

the packet was lost.● When engineer pinged any T160G in the ring to

another T160G, the packet was lost.

Malfunction Analysis● When engineer used T160G-1 to ping T160G-6,

no packet was lost in the transient process of

ring switching and recovering. That is, L2 data

forwarding is normal, ZESR switching is normal.● When Engineer used any T160G to ping

another T160G in the ring, the packet was lost

in the transient process of ring switching. Firstly,

the engineer doubted the fault is related with

the byte number of ping packet. The packet

was 8000 bytes; it was needed to sliced, so

a part of packets was lost. Engineer used the

smaller packet with 35 bytes to ping T160G and

found that 2-5 packets were still lost.● Engineer used the command debug on

T160G-3 to view. In the transient process of

ring switching, a larger number of ARP learning

packets were generated. When the r ing

switching trended to be stable, ARP learning

was stable. Engineer guessed the ARP table

would be updated when ZESR ring switched. A

spot of packets will be lost during the short time

of ARP relearning.

SolutionEngineer ran ARP static binding between

T160G-3 and T160G-4.

Consider T160G-3 as an example to configure

Key words:ZESR, ARP, MAC, convergence, ring network


www.zte.com.cn

21Data Products

ARP static binding on T160G-4 as shown below.

T160G-3(config)# interface vlan 10

T160G-3(config-if)# set arp static 192.168.1.4

xxxx.xxxx.xxxx

/*192.168.1.4 is the vlan10 address of T160G-4,

xxxx.xxxx.xxxx is the related MAC address.*/

Engineer used T160G-3 to ping T160G-4 again

Case Analysis

Double Independent Main Rings on ZESR⊙ Zhu Changfei / ZTE Corporation

Key words:ZESR, Independent main ring, management VLAN, multi-ring multi-domain

Network TopologyAs shown in Figure 1, the service VLAN

packets are transparently transmitted to T160G-1

and T160G-2 by T160G-3, T160G-4 and T160G-5,

T160G-6. At last, the packets uplink to C7609.

T160G-3 and T160G-4 take charge to transparently

transmit VLAN100-VLAN200’s packets. T160G-5

and T160G-6 take charge to transparently transmit

VLAN201-VLAN300’s packets. All VLAN packets

(VLAN100-300) are transparently transmitted

between T160G-1 and T160G-2. Six T160G adopts

VLAN 10 for network management and they enable

L3 address. The packets go to C4507 through

T160G-1, the network management server manage

the devices.

Network RequirementAccording to the requirement of network

structure and service, the network should be

designed as multi-ring multi-domain. That is,

T160G-1, T160G-2 and T160G-3, T160G-4

construct the main ring 1. T160G-1,

T160G-2 and T160G-5, T160G-6 construct

main r ing 2. The main r ing 1 and 2

intersect in T160G-1 and T160G-2.

Create an instance on each main ring.

Instance 1 protects the service VLAN

Figure 9. Single Ring Multiple Instances Configuration Example

and disconnected the link to switch the

ring. No packet was lost when using the

packet with 8000bytes to ping.

Engineer bound ARP table on each

T160G, and used large packet with 8000

bytes to ping each T160G, no packet was

lost. The problem was solved. ■



100-200 of main ring 1.

Instance 2 protects the service VLAN

201-300 of main ring 2. This kind of

network structures is doable.

Considering the network management

VLAN 10 constructs a ring on each main

ring, VLAN also needs an instance to

provide protection.

Network AnalysisAccording to the working principle of

ZESR, two independent main rings can not

protect the same VLAN. That is, VLAN 10

is protected by the instance on the main

ring 1, so it can not be protected by the

instance on main ring 2 (It is not permitted

by actual configuration). However, VLAN

10 also construct a ring on main ring 2, if

it can not be protected, it will be a loop in

VLAN10. The following two methods can

be adopted to solve the problem.wThe VLAN 10 should be a ring on main

ring 1 but not on main ring 2. VLAN 10

is added into the protection instance on

main ring 1, but the packets of VLAN

10 will be not transparently transmitted

between T160G-5 and T160G-6 on

main ring 2. Therefore, VLAN 10

will not be a ring on main ring 2, but it is still

manageable.

However, the ring status will be unstable if this

configuration is adopted. The ring will be switched

continuously. Meanwhile, T160G-5 and T160G-6

can be managed by single l ink only, so the

redundancy protection does not take effect. This

method is not recommended to be used.● C rea te i ns tance 3 on each ma in r i ng

respectively. Instance 3 is used to manage

VLAN 10, and there are 3 domains now. A node

supports 4 domains at most. Too many domains

in a ring will decrease the convergence speed

of ring. (The convergence speed of a single

domain can reach 50ms, the convergence

speed of multi-domain is 50ms~200ms).

Therefore, this method is not suggested either.

SummaryThe main ring and secondary ring is adopted

as network structure to satisfy such requirement.

That is, a ring works as main ring, and another

ring works as secondary ring. These two rings

share one instance to protect all services and

management VLAN. The ring mode is multi ring

single domain.

Double main rings is not scientific in network

structure, so it is not suggested in actual scenario. ■

Address Superposition⊙Yang Fei / ZTE Corporation

Key words:BAS, address superposition, address pool, dial

Network TopologyAs shown in Figure 1, the users of dial-

up services connect to the UAS 10400 and

get on-line after passing the authentication

of the dial-up services.

Malfunction SituationDuring the service rush hour (20:00~21:00)

www.zte.com.cn

23Data Products

everyday, some users could dial successfully but

they failed to access to the Internet. The users

could ping the address of UAS 10400 successfully

but failed to ping other addresses. If the users

hung up and retried to dial for many times, maybe

they could access to the Internet. The problem did

not exist if it was not in service rush hour.

Malfunction AnalysisEngineers solved the problem before by

changing relevant cards. This time, engineers

changed the ports, slots and cards. But the

problem still existed.

Therefore, the problem may be caused by

routes. The engineers took the following steps.

1 . The eng inee rs execu ted the show subscribers active username <username>

command to find an IP address of a user with the

problem (192.168.1.20).2. The engineers logged into another device

and input the trace route 192.168.1.20 command.

3. The engineers logged into another device

and executed the trace route 192.168.1.1

command. The address 192.168.1.1 was the

interface address of the address pool that the user

address (192.168.1.20) was in.

The results of step 2 and 3 showed that the

address was not the address of the UAS 10400). It

was the address of the MA5200.

The engineers logged into the MA5200 and

checked the configuration. They found that

there was a network segment of user address

192.168.1.0/24 which was the same with the

network segment configured on the UAS 10400.

Besides, on the S8016 there was a static route that

designated the next hop of 192.168.1.0/24 to the

MA5200.

Due to the address superposition and there was

no route to the UAS 10400 from 192.168.1.0/24

on the S8016, when the users connecting to the

UAS 10400 obtained the addresses in network

segment 192.168.1.0/24, they failed to access to

the Internet.

SolutionThe engineers deleted the network

segment 192.168.1.0/24 from the address

pool on the MA5200, and then configured

the back route of 192.168.1.0/24 to the

UAS 10400 on the S8016. The problem

was solved.

Experience SummaryAccording to the address distribution

a lgo r i t hm on the UAS 10400 , t he

addresses in the pool are distributed

from top to bottom. The address pool

192.168.1.0/24 was the last but one,

therefore, it was used only during the

service rush hour.

When the users hung up and redialed,

if there were addresses in the pool on the

top released at that time, the users could

obtain the addresses to access to the

Internet normally. ■




Switch CPU Utilization Ratio Abnormity⊙Zhang Fan / ZTE Corporation

Key words:3252, CPU, utilization ratio, ARP, ACL

Network TopologyOne ZXR10 3252 switch works as

the gateway and other two ZXR10 3252

switches work as the access switches. The

users use fixed IP addresses to access to

the network.

Malfunction SituationThe users had to wait for a long time

before they had an access to the Internet

successfully. Sometimes, they were failed

to have an access to the Internet.

The engineers logged into the gateway

switch to check the CPU utilization ratio.

They found that the CPU utilization ratio

was about 50% to 60%. When the users

pinged to the gateway, there was a long-

time delay.

Malfunction AnalysisTo find out the problem, the engineers

took the following steps.

1. The engineers logged into the

gateway switch to check the system

process information, as shown below.

3252#show taskinfo

NAME PRI STATUS MTICKS

Used(%)

------------- --- ------ ------ ------

Protocol 140 PEND 1

41.20

The result showed that the protocol

processes took up about 40% CPU

resources.

2. The engineers executed the show logging alarm command on the gateway switch to display

the alarm information, as shown below.

3252#show logging alarm

An alarm 21768 level 5 occurred at 23:36:01

04/01/2007 UTC sent by MCP %ACL PROTOCOL

PROTECT% Receive too many packets of

'arprequest' from port fei_1/1









……

The result showed that the switch received a lot

of ARP REQUEST messages.

3. The engineers execute the debug arp

command to check the ARP processes on the

switch, as shown below.

3252#debug arp

ARP debugging is on

18:55:48 IP ARP:req filtered src 192.168.11.175

000D.8769.079E, dst 192.168.222.41 wrong cable

vlan308



vlan308



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25Data Products

vlan308

……

The result showed that there were some items

that could not be filtrated by the ARP source

filtration function.

According to the arp source-filtered rule, when

an interface receives an ARP message, the system

searches the route according to the source IP

address. If the route belongs to the local interface,

the device accepts the message; otherwise, the

device discards the message. By default, the ARP

source filtration function is enabled.

In this case, the gateway switch received a

lot of ARP REQUEST messages. The source IP

address of these ARP REQUEST messages was

not in the address range of its subnet. That is,

an illegal user sent the messages. Therefore, the

messages could not pass the ARP source filtration

and were discarded.

Since these messages were discarded,

the gateway switch should not process these

messages. Why did the CPU utilization ratio keep

high? It was because that the ARP source filtration

function was implemented by the software and

CPU took part in the judgment and calculation.

Therefore, these messages cost a lot of CPU

resources.

SolutionThe engineers used ACL to filtrate the illegal

messages, as shown below.

acl basic number 1

rule 1 deny 192.168.11.0 0.0.0.255 /*refuse

the packets with source IP addresses in network

segment 192.168.11.0/24 */

rule 2 permit any

!

Interface fei_1/1

ip access-group 1 0 in /*apply the ACL to

the interface*/

!

Interface fei_1/4

ip access-group 1 0 in

!

The ACL function is implemented by

hardware. When the interface received

the illegal messages, the messages were

discarded directly and did not cost the

CPU resources.

Experience SummaryWith the development of the network,

there are more and more network viruses.

In this case, a host of the user infected

the virus. The virus changed the source IP

address of the messages and sent them

to the switch. This affected the switch and

other users.

The anti-virus ACL can be applied to

interfaces to protect the host effectively.

A common anti-virus ACL configuration is

shown below.

acl extend number 101

rule 1 deny tcp any any eq 135









rule 10 deny udp any any eq 1433









rule 19permit ip any any

! ■



Malfunction SituationThe broadband devices such as

broadband switch, ADSL MODEM, optical

fiber transceiver are usually destroyed by

lighting stroke on thunderstorm season.

This problem should receive much concern

because it causes the communication

interruption and brings a lot of economic loss.

Malfunction AnalysisIt is well known that the lighting stroke

seeks a fast path to release electricity

by conductor. Broadband devices are

adopted by AC power supply, so the AC

power supply cable is the conductor.

For broadband switch, the outdoor

network cables are conductors, the lighting

stroke will be induct to switch by RJ45

port.

For ADSL MODEM, the outdoor cable

and user access line are conductors.

Optical transceiver is connected

with broadband switch by RJ45 port.

The lighting stroke will be inducted and

destroyed optical transceiver by RJ45 port

from broadband switch.

The reasons that broadband devices

are easily destroyed by lighting stroke can

be divided into the following four points.● CMOS application specific integrated

circuits are adopted by broadband

device largely. These integrated circuit

components are sensitive for induction.

Moreover, the conducted l ighting

stroke is stronger and faster. If the lighting

protection circuit is not designed well on port,

the broadband device is easily destroyed.● When the protection earthing terminal of

broadband device is well installed through

the excellent grounding device, it can provide

a release path for l ighting stroke. Some

constructors and maintenance staffs do not

pay attention to grounding installation, some

grounding devices are not installed completely,

and some device’s grounding resistances are

incompetent. ● Most of cable junction boxes do not have

lighting stroke protection.● During the process of laying cables on

residential district, some problems in regard to

the constructors' casual choice of cables, the

cable layout is jumbled and unreasonable. If

a cable is inducted by lighting stroke, a port or

broadband switch will be destroyed.

SolutionThe countermeasures of l ight ing stroke

protection on broadband devices can be divided

into the following five points.● Broadband device manufacturers should

analyze the induction path further and develop

the protection circuit.● The depar tmen t i n charge o f ne twork

construction should develop supervision cause

to assure engineering quality, especially for the

grounding device installation. The unqualified

engineering should be reformed and rectified

until it achieves the qualified level.

Lighting Stroke Damage on Broadband Device ⊙Zhu Shaohua/ China Telecom, Shishou Branch

Key words:lighting stroke, broadband switch, ADSL MODEM, optical transceiver, grounding, lightning

protection

www.zte.com.cn

27Data Products

A Tip of Batch Pasting on Hyper Terminal and SecureCRT⊙Bai Ping / ZTE Corporation

Key words:Hyper Terminal, secureCRT, batch pasting, input delay

Malfunction SituationWhen users perform batch pasting on router or

Ethernet switch by Hyper Terminal or SecureCRT, the

fault occurs. It causes the running configuration error,

and user needs to modify the configuration a lot.

The Hyper Terminal error is shown in Figure 1

The SecureCRT error is shown in Figure 2.

SolutionThe interval is too short when laptop or PC

sends command to router or Ethernet switch. The Figure 1. Hyper Terminal Error

Figure 2. SecureCRT Error Figure 3. Parameter Interface

● On the area where lighting occurs frequently,

the outdoor cable junction box should be

replaced with cable junction box with lighting

stroke protection. Make sure that the grounding

device buried is excellent.● The broadband switch lying on residential

district should be rebuilt designedly and step by

step.

● The department in charge of network

maintenance should arrange the staff

to examine all grounding condition

of broadband devices before each

thunderstorm season, and perform

electrical test on grounding resistance

of earthing cable. Make sure that

grounding resistance is qualified. ■



devices can not response the command in time

that causes the fault occurs.

To solve this fault, modify the value of command

input delay on Hyper Terminal or SecureCRT.● Hyper Terminal

1. Click File → Parameters, an interface

appears as shown in Figure 3.

2. Click ASCII Setup, an interface appears as

shown in Figure 4. Enter 500 milliseconds into line

delay box.● SecureCRT

1. Click Options → Global Options →Category →Options →Advanced, enter 500 into <Line send

delay> box. That is, the line delay is modified into

500 milliseconds, as shown in Figure 5.

After modifying the line delay, the successful

effect of batch pasting about Hyper Terminal is

shown in Figure 6. The successful effect of batch

pasting about SecureCRT is shown in Figure 7.

SummaryWhen lots of commands need to paste, user

can modify the line delay of Hyper Terminal and

SecureCRT firstly, and then paste the commands

to Hyper Terminal or SecureCRT. This improves

the work greatly. ■

Figure 4. Line Delay Interface

Figure 5. SecureCRT Interface

Figure 6. Successful Batch Pasting on Hyper Terminal Figure 7. Successful Batch Pasting on SecureCRT

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Documents

Preface - Experience, Issue134(Data Products).pdf · Preface Maintenance Experience Editorial Committee Maintenance Experience Newsroom ... that EAPS takes less time than 50ms to