Switches

Sep 8 2009   9:45AM GMT

Remote Telnet useful tips!

Posted by: Yasir Irfan
Switches, Cisco, Cisco Tips, Cisco 3560, Cisco Learning, Network Troubleshooting, IOS commands, Cisco Routers, reload, Cisco Switch, Cisco Troubleshooting, Router Troubleshooting, Telnet, SSH

 

We all work remotely with Cisco routers and Switches, we often do login to do some configuration changes in the Cisco routers and Switches. What if we configured wrongly in the live Cisco routers and Switches which are located in the remote sites, we don’t enjoy the liberty of resetting the devices unless we have control over the power distribution.

 

In this scenario the “reload” command proves to be very handy and useful. Just before making any changes to the configuration we can use the “reload” command as demonstrated below

 

ITKE-Cisco#reload in ?

Delay before reload (mmm or hhh:mm)

 

ITKE-Cisco#reload in 10

 

System configuration has been modified. Save? [yes/no]: no

Building configuration…

[OK]

Reload scheduled in 10 minutes by yasir on vty0 (10.0.0.5)

Proceed with reload? [confirm]

ITKE-Cisco#

ITKE-Cisco#

 

 

***

*** — SHUTDOWN in 0:05:00 —

***

 

The above demonstrated command will reload the device in 10 minutes. After applying the “reload” command we can proceed with the configuration changes. If things go wrong and we lost connectivity

to the device, then try back after 10 minutes as the device will get reloaded with the original startup-configuration which can helps us to restore the connectivity to the device.

 

Once we are sure about the new configuration and its working properly without any hassles there is always a way  “reload cancel” command is there to cancel the reload.

 

ITKE-Cisco#reload cancel

 

I find this command to be very handy and useful especially when we have to telnet or SSH to remote Cisco router or a Switch.

Sep 5 2009   8:07AM GMT

Review for CCNP BCMSN Official Exam Certification Guide (4th Edition)

Posted by: Yasir Irfan
CCNP, CCNP BCMSN, CCNP Books, Cisco BCMSN (642-812) exam, CCNP BCMSN Official Exam Certification Guide, CCNP Official Certification Library, Cisco Press, Review for CCNP BCMSN Official Exam Certification Guide, Yasir, Boson Exams, HSRP, GLBP, David Hucaby, Router, Supervisor and Power redundancy, Switching, Switches, Router Supervisor and Power redundancy, Cisco Exams, CCNP Preparation

 

Hi folks, as I received a CCNP Official Certification Library, fifth edition thanks to Cisco Press (Jamie) for the great support lending on me all the time. To brief about the CCNP Official Certification Library, fifth edition is a comprehensive package for the four Cisco CCNP exams BCMSN, BSCI, ISCW and ONT. Starting from this post I will try my best review all the four Certification books comes with the CCNP Official Certification Library, fifth edition thanks. To start with I will go with the CCNP BCMSN Official Exam Certification Guide, fourth edition.

The CCNP BCMSN Official Exam Certification Guide, fourth edition is a true guide for preparing for the Cisco BCMSN (642-812) exam. The author David Hucaby did a wonderful job by the explaining the material in short concise way that facilitates easy learning.

The CCNP BCMSN Official Exam Certification Guide, fourth edition is divided into six parts , each part is well written and  more over its easy to understand. The most liked chapter for me is the Router, Supervisor and Power redundancy. Thanks to David Hucaby, I was able to migrate our network from HSRP to GBLP succefully. He explained the concept very well like I said it’s really easy to understand.

The CCNP BCMSN Official Exam Certification Guide, fourth edition does have the Scenarios for final preparations  There are nine scenarios covering wide range of concepts and are helpful not only from the exam point of view but also it can be used to troubleshoot the problems in real networks faced by some folks.

One more amazing thing I liked in the CCNP BCMSN Official Exam Certification Guide, fourth edition is the practice exams which are handful for the folks who has little exposure to real world networks, but it’s always recommend to have some hands on experience with Switches configuration and analysis.

Overall an excellent guide which can leads you to taste the success of passing Cisco BCMSN (642-812) exam. I would rate this guide 4.5 out of 5.

Apr 17 2009   4:42AM GMT

VLAN Trunking Protocol (VTP) Overview – Series 5

Posted by: Yasir Irfan
VLAN Trunking Protocol, VTP, Cisco Proprietary, Layer 2, Cisco, IEEE, Cisco Catalyst Switches, Switches, VTP Overview, What is VTP, VTP Domain, GVRP, VTP Modes, VTP Server, VTP Client, VTP Transparent

These days I am in Bangalore with my parents just enjoying my holidays. Guess what today night I am travelling to Singapore and Malaysia with my wife. May be I  will not be in a position post more posts this month as I am relaxing and enjoying the beauty of Nature. For sure I am going to share the natural beauty with all you guys.

Mean while before departing to Singapore I thought let me continue my series on VTP , in this series let s focus on VTP modes. There three type of VTP modes

a)      VTP Server

b)      VTP Client

c)      VTP Transparent

Mar 9 2009   5:14AM GMT

VLAN Trunking Protocol (VTP) Overview – Series 4

Posted by: Yasir Irfan
VLAN Trunking Protocol, VTP, Cisco Proprietary, Layer 2, Cisco, IEEE, Cisco Catalyst Switches, Switches, VTP Overview, What is VTP, VTP Domain, GVRP

What do you think what happens? If a new Cisco Catalyst® switch is placed between any two VTP domains, the Cisco Catalyst® switch will join the VTP domain identified by the first VTP update it receives. Just check the below example.

 

 

The VTP domain can be changed to another in a Cisco Catalyst® switch by using the CLI prompt, this is the only way you can change.

Feb 25 2009   11:23AM GMT

VLAN Trunking Protocol (VTP) Overview – Series 3

Posted by: Yasir Irfan
VLAN Trunking Protocol, VTP, Cisco Proprietary, Layer 2, Cisco, IEEE, Cisco Catalyst Switches, Switches, VTP Overview, What is VTP, VTP Domain, GVRP

In Cisco Catalyst® switches the VTP domain can be added through CLI configuration or else it can be learnt from an adjacent VTP Cisco Catalyst® switch. Let’s see this from the below example

 

Switch C is added to the network connecting via a trunk port to Switch B with no VTP domain configured, in this mode when the Switch C receives the first VTP update from the adjacent Switch B , it will become the part of the VTP domain ITKE as identified in the VTP update.

Feb 23 2009   6:35AM GMT

VLAN Trunking Protocol (VTP) Overview – Series 2

Posted by: Yasir Irfan
VLAN Trunking Protocol, VTP, Cisco Proprietary, Layer 2, Cisco, IEEE, Cisco Catalyst Switches, Switches, VTP Overview, What is VTP, VTP Domain, GVRP

In my previous post I just introduced the VLAN trunking protocol; let’s talk about the VTP domain.

The VTP domain consists of a group of logical group of Cisco Catalyst Switches that are part of the same VTP management domain. A  Cisco Catalyst Switch can belong only to one VTP domain at any time,

 

 

The VTP domain is a logical group of switches that will share VLAN information. Each switch can belong only to one VTP domain in addition to sharing the VLAN information with all other Cisco Catalyst Switches in the same VTP domain. Cisco Catalyst Switches in different VTP domains drops any VTP updates received from Cisco Catalyst Switches.

Feb 21 2009   6:21AM GMT

VLAN Trunking Protocol (VTP) Overview – Series 1

Posted by: Yasir Irfan
VLAN Trunking Protocol, VTP, Cisco Proprietary, Layer 2, Cisco, IEEE, Cisco Catalyst Switches, Switches, VTP Overview, What is VTP, VTP Domain, GVRP

What is a VLAN Trunking Protocol (VTP)?

VLAN Trunking Protocol (VTP) is a Cisco proprietary Layer 2 messaging protocol that manages the addition, deletion, and renaming of VLANs for the Cisco Catalyst Switches in the same VLAN Trunking Protocol (VTP) domain.  VLAN Trunking Protocol (VTP) enables Cisco Catalyst Switches to exchange and maintain consistent VLAN information amongst a group of Cisco Catalyst Switches.

 

For example, information for the VLAN 50 defined in Cisco Catalyst Switch A is propagated via VTP updates to all other Cisco Catalyst Switches (Switches B, C and D) in the same VTP domain, the other Cisco Catalyst Switches B, C and D will all end up adding VLAN 50 in their local VLAN data base. VTP is available on most of the Cisco Catalyst Family products.

The comparable IEEE standard in use by other manufacturers is GVRP.

Feb 18 2009   9:33AM GMT

Cisco Etherchannel Overview and how it can be configured in Cisco Catalyst Switches – Series 9

Posted by: Yasir Irfan
Cisco, Cisco Systems, Cisco Tips, Etherchannel, Etherchannel configuration, Etherchannel restrictions, Switches, Switching, Layer3 EtherChannel Configuration, PAGP EtherChannel Configuration, LACP, Cisco 3560 Catalyst Switch, Cisco online learning module, layer-2-design

Dear Friends

 Here we go,we are coming to the conclusion of the Ether channel series, I my self learned a lot and enjoyed while writing posts. Hope some of you are benifited from this series. Just before concluding this series,  I would stongly recommend you guys to check this wonderful quick learning module from Cisco Systems. which foucses on layer-2-design which might be helpful to you guys.

Feb 7 2009   5:52AM GMT

Cisco Etherchannel Overview and how it can be configured in Cisco Catalyst Switches – Series 8

Posted by: Yasir Irfan
Cisco, Cisco Systems, Cisco Tips, Etherchannel, Etherchannel configuration, Etherchannel restrictions, Switches, Switching, Layer3 EtherChannel Configuration, PAGP EtherChannel Configuration, LACP, Cisco 3560 Catalyst Switch

Now we are reaching towards the end of this series, one more post to go.  

Let’s proceed further and we will see how to configure a Layer 3 Etherchannel using the PAgp Protocol (Port Aggregation Protocol) in Cisco Catalyst Switches.

Here is the scenario which we will follow

 

From the above diagram we have two Cisco 3560 Catalyst Switches named ITKESW01 and ITKESW02.

We will configure a Layer 3 Etherchannel between the Cisco 3560 Catalyst Switches  ITKESW01 and ITKESW02. The  Giga Ethernet ports 0/45, 0/46/,0/47 & 0/48 on a Cisco 3560 Catalyst Switches  ITKESW01 are connected to Giga Ethernet ports 0/1,0/2,0/3 and 0/in Cisco 3560 Catalyst Switch  ITKESW02.

 

The configuration is as follows

 

Configuration in the Cisco 3560 Catalyst Switch  ITKESW01

 

ITKESW01#config t

ITKESW01(config)# interface port-channel 1

ITKESW01(config-if)# no switchport

ITKESW01(config-if)# no shutdown

ITKESW01(config-if)# ip address 192.168.1.1 255.255.255.0

ITKESW01(config-if)# end

 

ITKESW01#config t

ITKESW01(config)# interface range gigabitEthernet 0/45 – 48

ITKESW01(config-if-range)# no switchport

ITKESW01(config-if-range)# no ip address

ITKESW01(config-if-range)# channel-group 1 mode desirable

ITKESW01(config-if-range)#end

Note: This example shows how to configure Gigabit Ethernet ports 0/45 – 0/48   into port channel 1 with PAgP mode desirable

Note: The “no switchport” command is required to change interface from layer2 to layer3 mode.

 

Configuration in the Cisco 3560 Catalyst Switch  ITKESW02

ITKESW02#config t

ITKESW02(config)# interface port-channel 1

ITKESW02(config-if)# no switchport

ITKESW02(config-if)# no shutdown

ITKESW02(config-if)# ip address 192.168.1.2 255.255.255.0

ITKESW02(config-if)# end

 

ITKESW02#config t

ITKESW02(config)# interface range gigabitEthernet 0/1 – 4

ITKESW02(config-if-range)# no switchport

ITKESW02(config-if-range)# no ip address

ITKESW02(config-if-range)# channel-group 1 mode auto

ITKESW02(config-if-range)#end

Note: This example shows how to configure Gigabit Ethernet ports 0/1 – 0/4   into port channel 1 with PAgP mode auto

 

Note: The “no switchport” command is required to change interface from layer2 to layer3 mode.

 

Do use  “show etherchannel” command to display port-channel information after configuration and remember to save the configuration.

Jan 19 2009   5:49AM GMT

Cisco Etherchannel Overview and how it can be configured in Cisco Catalyst Switches – Series 7

Posted by: Yasir Irfan
Cisco, Cisco Systems, Cisco Tips, Etherchannel, Etherchannel configuration, Etherchannel restrictions, Switches, Switching, Layer 2 EtherChannel Configuration, LACP EtherChannel Configuration, LACP, Cisco 3560 Catalyst Switch

Here we go, I will continue the series of Etherchannel overview, in my last post related to Etherchannel I showed how to configure a Layer 2 Etherchannel using the Cisco’s proprietary a PAGP (port aggregation protocol) Protocol in Cisco Catalyst Switches.

Now it’s the time to proceed further and we will see how to configure a Layer 2 Etherchannel using the LACP Protocol (Link Aggregation Protocol) in Cisco Catalyst Switches.

Here is the scenario which we will follow

From the above diagram we have two Cisco 3560 Catalyst Switches named ITKESW01 and ITKESW02.

We will configure a Layer 2 Etherchannel between the Cisco 3560 Catalyst Switches  ITKESW01 and ITKESW02. The  Giga Ethernet ports 0/45, 0/46/,0/47 & 0/48 on a Cisco 3560 Catalyst Switches  ITKESW01 are trunk ports  and they are connected to Giga Ethernet ports 0/1,0/2,0/3 and 0/4 (also trunk ports in desirable mode) in Cisco 3560 Catalyst Switch  ITKESW02.

 

The configuration is as follows

 

Configuration in the Cisco 3560 Catalyst Switch  ITKESW01

 

First run the command “Show interfaces trunk

 

ITKESW01#sho interfaces trunk

 

Port        Mode             Encapsulation  Status        Native vlan

Gi0/45      desirable                n-isl         trunking            1

Gi0/46      desirable                n-isl         trunking            1

Gi0/47      desirable                n-isl         trunking            1

Gi0/48      desirable                n-isl         trunking            1

 

Port        Vlans allowed on trunk

Gi0/45        1-4094

Gi0/46        1-4094

Gi0/47        1-4094

Gi0/48        1-4094

 

Port        Vlans allowed and active in management domain

Gi0/45        1

Gi0/46        1

Gi0/47        1

Gi0/48        1

 

Port        Vlans in spanning tree forwarding state and not pruned

Gi0/45       1

Gi0/46       1

Gi0/47       1

Gi0/48       1

 

ITKESW01#

 

Second Step configure the Giga Ethernet ports 0/45 to 0/48 in the Etherchannel

 

ITKESW01#config t

ITKESW01(config)# interface range gigabitEthernet 0/45 – 48

ITKESW01(config-if-range)# channel-protocol lacp

 

Note: LACP protocol is configured to be used in this channel

 

ITKESW01 (config-if-range)# channel-group 1 mode active

Note: A logical port-channel interface is automatically created when ports are grouped into a channel group.

Configure the mode active to be used in LACP

Configuration in the Cisco 3560 Catalyst Switch  ITKESW02

 

ITKESW02#sho interfaces trunk

 

Port        Mode             Encapsulation  Status        Native vlan

Gi0/1      desirable            n-isl         trunking            1

Gi0/2      desirable            n-isl         trunking            1

Gi0/3      desirable            n-isl         trunking            1

Gi0/4      desirable            n-isl         trunking            1

 

 

Port        Vlans allowed on trunk

Gi0/1        1-4094

Gi0/2        1-4094

Gi0/3        1-4094

Gi0/4        1-4094

 

 

Port        Vlans allowed and active in management domain

Gi0/1        1

Gi0/2        1

Gi0/3        1

Gi0/4        1

 

 

Port        Vlans in spanning tree forwarding state and not pruned

Gi0/1       1

Gi0/2       1

Gi0/3       1

Gi0/4       1

 

ITKESW02#

 

Second Step configure the Giga Ethernet ports 0/1 to 0/4 in the Etherchannel

 

ITKESW02#config t

ITKESW02(config)# interface range gigabitEthernet 0/1 – 4

ITKESW02(config-if-range)#channel-protocol lacp

 

Note: LACP protocol is configured to be used in this channel

 

ITKESW02 (config-if-range)# channel-group 1 mode active

Note: A logical port-channel interface is automatically created when ports are grouped into a channel group.

Configure the mode active to be used in LACP

Now run show command to display the Etherchannel configurations on the Cisco 3560 Catalyst Switches  ITKESW01 and ITKESW02

ITKESW01#sho etherchannel 1 summary

Flags:  D - down        P - in port-channel

        I - stand-alone s - suspended

        H - Hot-standby (LACP only)

        R - Layer3      S - Layer2

        u - unsuitable for bundling

        U - in use      f - failed to allocate aggregator

        d - default port

 

Number of channel-groups in use: 1

Number of aggregators:           1

 

Group  Port-channel  Protocol    Ports

——+————-+———–+———————————————–

1      Po1(SD)          LACP      Gi0/45 (P)   Gi0/46 (P)  Gi0/47 (P)  Gi0/48 (P)  

ITKESW01#

 

ITKESW02#sho etherchannel 1 summary

Flags:  D - down        P - in port-channel

        I - stand-alone s - suspended

        H - Hot-standby (LACP only)

        R - Layer3      S - Layer2

        u - unsuitable for bundling

        U - in use      f - failed to allocate aggregator

        d - default port

 

Number of channel-groups in use: 1

Number of aggregators:           1

 

Group  Port-channel  Protocol    Ports

——+————-+———–+———————————————–

1      Po1(SD)          LACP     Gi0/1 (P)   Gi0/2 (P)  Gi0/3 (P)  Gi0/4 (P)  

ITKESW02#