Posts tagged cisco

Cisco Tricks

Feb 6th

Posted by admin in General

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Have an unsupported gbic module ?

enable
show interfaces status err-disabled

conf t
no errdisable detect cause gbic-invalid
service unsupported-transceiver
wr

 

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Hot adding or removing a Cisco 3750 from a stack

Sep 19th

Posted by admin in General

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When using a Cisco 3750 stack connected through stackwise technology you can add or remove a Cisco switch while the stack stays on. If you are adding or removing a switch from the stack, it is very important that the switch is turned OFF. The rest of the stack can keep doing its business.

For adding a switch to the stack follow these steps:

Step 1) On the new switch give the global command: switch stack-member-number provision type

Type is the type of switch you are adding to the stack.

When adding for example a third Cisco switch to the Cisco stack, use the following command:

switch 3 provision ws3750g-24t

Step 2) Power off the new stack member

Step 3) Connect the new member to the Cisco stack using the stacking cables, 1 loop at a time.

Step 4) Power on the new stack member. The switch will come alive and will receive the Cisco IOS version from the master, when that is completed it will be ready to service network requests.

For removing a member switch from the stack use the following steps:

Step 1) Power off the stack member to be removed.

Step 2) Remove the stackwise cable from the switch.

Step 3) Issue the following command on the stack master: no switch stack-member-number provisiontype

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Cisco – Port mirroring

Sep 13th

Posted by admin in General

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Voilà comment faire pour mirrorer un port:

 

conf t
monitor session 1 source interface fastethernet 0/23
monitor session 1 destination interface fastethernet 0/24

Il est également possible de mirrorer un VLAN

 

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Cisco IOS Tips and Tricks

Jul 7th

Posted by admin in General

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Il est toujours utile de connaitre les raccourcis clavier. Cela permet d’aller plus vite :)

 

Keyboard Shortcuts

Voici celles que j’utilise le plus

Ctrl+A Move cursor to the beginning of the line
Ctrl+E Move cursor to the end of the line
Up Retrieve last command from history
Down Retrieve next command from history
Ctrl+W Erase previous word
Ctrl+U Erase the entire line
Ctrl+C Exit configuration mode
Ctrl+Z Apply the current command and exit configuration mode

Modifying output

On peut modifier la sortie d’un show à l’aide des commandes “begin, include, exclude et section”.

Router# show run | begin bgp
router bgp 65500
 no synchronization
...
!
end

 

Il est aussi possible d’utiliser des expressions régulières dans les show

Router# sh ip int | inc line protocol|access list is [^ ]+$
FastEthernet0 is up, line protocol is up
  Inbound access list is deny10
FastEthernet1 is up, line protocol is up
  Inbound access list is 11
FastEthernet2 is up, line protocol is up
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google search ios

Cisco IOS – Google power

May 19th

Posted by admin in General

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Google power search

By the “Power of Google”, you can do anything and averything you want:-).

Juste copy paste this command to find IOS

intitle:index.of ios parent directory bin

or just click below

http://www.google.com/search?hl=en&q=intitle:index.of+ios+parent%20directory+bin

 

 

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Cisco feature set upgrade

May 17th

Posted by admin in General

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Error: The image in the archive which would be used to upgrade Error: system number 1 does not support the same feature set.

Cisco it seems included this sanity check,as of 12.2(35), to prevent you from accidentally changing the feature set during a IOS upgrade, not a nice thing to happen on a production switch, when things go belly up.

You will get the above error when upgrading the IOS and changing the feature set. IE if you upgrade the image from IPBASE 12.2(35)SE5 to ADVIPSERVICESK9 12.2(25)SEE4.

So to bypass this, you can add the /allow-feature-upgrade parameter, to the archive download-sw command.

Example :

#archive download-sw /overwrite /allow-feature-upgrade tftp:10.1.1.1/c3560-advipservicesk9-tar.122-25.SEE4.tar

If you need more info on how to upgrade the IOS on a Cisco 3560, visit http://www.cisco.com/en/US/products/hw/switches/ps5023/products_configuration_example09186a00804799d7.shtml#cfbin1.

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Cisco – Spanning Tree

May 10th

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Identifying a Bridging Loop

Suspect a loop if you see the following:

  • You capture traffic on a link and see the same frames multiple times.
  • All users in a bridging domain have connectivity problems at the same time.
  • There is abnormally high port utilization.

To remedy a loop quickly, shut redundant ports and then enable them one at a time. Some switches enable debugging of STP to help in diagnosing problems. The following commands are useful for isolating a bridging loop

 

show interfaces
show spanning tree
show bridge
show process cpu
debug spanning tree
show mac address-table aging-time vlan#
show spanning-tree vlan vlan# detail

Spanning-Tree Best Practices

To optimize data flow in the network, design and configure Spanning Tree in the following ways:

  • Statically configure switches to be the primary and secondary root bridges by setting priority values.
  • Consider which interfaces will become designated and root ports (possibly set port priorities/path cost).
  • Tune STP using the tools detailed in this section.
  • Enable UDLD aggressive mode on all fiber interfaces.
  • Design STP domains that are as simple and contained as possible by using multilayer switches and routed links.
  • Use PVRST+ or MST for the fastest convergence times.
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