Tài liệu Etherchannel LAN Switching Troubleshooting pdf

Your network administrator feels performance would improve if a second 100MB link between the distribution layer switches and the access layer switches were added.. Your network admini

Lab 5.2.9 Etherchannel LAN Switching Troubleshooting

Fa 0/12 FastEthernet

Crossover Connection ALSwitch

10.8.1.1/24 2900XL-Ent

4006 L3

Client 10.8.1.3/24

Objective

The primary function of the spanning-tree algorithm (STA) is to cut loops cre-ated by redundant links in bridged networks The Spanning-Tree Protocol (STP) operates at Layer2 of the OSI model and, by the means of bridge proto-col data units (BPDUs) exchanged between bridges, elects the ports that will eventually forward or block traffic This protocol can fail in some specific cases and troubleshooting the resulting situation can be very difficult, depending on the design of the network The most important part of troubleshooting is done before the problem occurs

For this exercise, utilize a systematic approach to troubleshooting Etherchannel Switch network

Scenario

This network is not part of the International Travel Agency

As the Enterprise Network Administrator, you have a small, switched network with all clients existing in the same VLAN There are currently no fault tolerant links in your network You have several hosts communicating to each other be-tween the distribution layer and access layer switches at 100MB full duplex Your network administrator feels performance would improve if a second

100MB link between the distribution layer switches and the access layer

switches were added Your network administrator adds a new crossover cable between DLSwitch and ALSwitch and reports that communications between both switches has stopped, however, the rest of the network continues to oper-ate DLSwitch indicates the following message:

“STP loop - channel 2/3-4 is disabled in vlan 1”

You must investigate the Spanning-Tree configuration and Port-Channels to ensure proper configuration

Lab Tasks

Build the network according to the diagram above

Cable the lab as shown in the diagram

Clear the DLRouter configuration using the following commands:

Router#erase start

Erasing the nvram filesystem will remove all files! Continue? [confirm]y[OK]

Erase of nvram: complete

Router#reload

Proceed with reload? [confirm]y

Clear the DLSwitch configuration using the following commands:

Console> (enable) clear config all

This command will clear all configurations in NVRAM

This command will cause ifIndex to be reassigned on the next system startup

Do you want to continue (y/n) [n]? y

Console> (enable) reset

This command will reset the system

Do you want to continue (y/n) [n]? y

Clear the ALSwitch configuration and VLAN database using the following com-mands:

ALSwitch#clear start

Erasing the nvram filesystem will remove all files! Continue? [confirm]y[OK]

Erase of nvram: complete

ALSwitch#delete vlan.dat

Delete filename [vlan.dat]?

Delete flash:vlan.dat? [confirm]y

ALSwitch#reload

Proceed with reload? [confirm]y

Load the file called Lab5-2-9-DLSwitchBrokenConfig.txt into the DLSwitch switch Load the file called Lab5-2-9-ALSwitchBrokenConfig.txt into the

ALSwitch switch

Configure the client with the ip address, default gateway, and subnet mask listed in the diagram

Step 1

Define your problem

Step 2

Gather the Facts

Based on the current information you have, issue the following commands to narrow down your possibilities The first thing to check is your connections

On the ALSwitch, check the interfaces

ALSwitch#show ip interface brief

Interface IP-Address OK? Method Status Protocol VLAN1 10.8.1.1 YES NVRAM up up

FastEthernet0/1 unassigned YES unset down down FastEthernet0/2 unassigned YES unset down down FastEthernet0/3 unassigned YES unset down down FastEthernet0/4 unassigned YES unset down down FastEthernet0/5 unassigned YES unset down down FastEthernet0/6 unassigned YES unset down down FastEthernet0/7 unassigned YES unset down down FastEthernet0/8 unassigned YES unset down down FastEthernet0/9 unassigned YES unset down down FastEthernet0/10 unassigned YES unset down down FastEthernet0/11 unassigned YES unset down down FastEthernet0/12 unassigned YES unset up up

(Note that both FastEthernet 0/1 and 0/2 interfaces are down.)

On the DLSwitch, check the interfaces

DLSwitch> (enable) show port 2

Port Name Status Vlan Level Duplex Speed Type

- - - - - - - -

2/1 connected 1 normal full 1000 No Connector 2/2 connected 1 normal full 1000 No Connector 2/3 errdisable 1 normal auto auto 10/100BaseTX 2/4 errdisable 1 normal auto auto 10/100BaseTX 2/5 notconnect 1 normal auto auto 10/100BaseTX 2/6 notconnect 1 normal auto auto 10/100BaseTX 2/7 notconnect 1 normal auto auto 10/100BaseTX 2/8 notconnect 1 normal auto auto 10/100BaseTX 2/9 notconnect 1 normal auto auto 10/100BaseTX - output truncated -

2/34 notconnect 1 normal auto auto 10/100BaseTX Port AuxiliaryVlan AuxVlan-Status InlinePowered PowerAllocated Admin Oper Detected mWatt mA @51V - - - - - - - -

2/1 none none - - - - -

2/2 none none - - - - -

2/3 none none - - - - -

2/4 none none - - - - -

- output truncated -

Port Status Channel Admin Ch Mode Group Id - - - - -

2/1 connected auto silent 22 0

2/2 connected auto silent 22 0

2/3 errdisable on 25 802 2/4 errdisable on 25 802 2/5 notconnect auto silent 23 0

2/6 notconnect auto silent 23 0

2/7 notconnect auto silent 23 0

- output truncated -

Last-Time-Cleared -

Tue Jun 12 2001, 20:28:19

(Note that both ports 2/3 and 2/4 are in a “errdisable” status.)

Step 3

Based on your observations of the ALSwitch, it appears as though the

ALSwitch inputs ports are down On the DLSwitch you see that the DLSwitch is disabling the port due to an error condition Use the following commands to help gather facts about the DLSwitch

Attempt to re-enable the ports on the DLSwitch

DLSwitch> (enable) set port enable 2/3

Port 2/3 enabled

DLSwitch> (enable) set port enable 2/4

Port 2/4 enabled

DLSwitch> (enable) 2001 Jun 12 21:10:03 %PAGP-5-PORTTOSTP:Port 2/3 joined bridge port 2/3-4

2001 Jun 12 21:10:07 %PAGP-5-PORTTOSTP:Port 2/4 joined bridge port 2/3-4

2001 Jun 12 21:10:44 %SPANTREE-2-CHNMISCFG: STP loop - channel 2/3-4 is disabled

in vlan 1

2001 Jun 12 21:10:44 %PAGP-5-PORTFROMSTP:Port 2/3 left bridge port 2/3-4

2001 Jun 12 21:10:44 %PAGP-5-PORTFROMSTP:Port 2/4 left bridge port 2/3-4

DLSwitch> (enable)

Step 4

Consider the possibilities Use the information you have and your knowledge of switches to isolate the problem

Step 5

Create an Action Plan

Step 6

Implement the Action Plan

Step 7

Observe the Results of the Action Plan

On the ALSwitch, check the interfaces using the “show ip interface

On the DLSwitch, check the interfaces using the “show port 2” command Annotate changes from what you saw in step 2

Step 8

Document your work