3750 Switch Password Recovery

While having a class of CCNP-SWITCH, i had to perform some labs using layer-3 switch, i used cisco-3750 for the lab, i found that two of the switches are password protected as we purchased that few days before so i had to recvoer the password. Connect the PC to the console port of the switch and if switch is power on, unplug the power and again plug power and press the mode button (it depends on series to series for how long you have to press mode button untill the light turn to green then release it, in 3750 you may required to press for around 15-seconds).

The switch should then give you this prompt

switch:

To initialize the flash file system, run the command

switch: flash_init

The switch will now print few messages about the flash memeory, now the next command will be the helper command.

switch: load_helper

Now we have to list the contents of our flash memory using folowing command.switch:

swith: dir flash:

This will display you the output somewhat like this as show below
The switch file system appears:

Directory of flash:
13 drwx 192 Mar 01 1993 22:30:48 c3750-ipservices-mz-122-25.SEB
11 -rwx 5825 Mar 01 1993 22:31:59 config.text
18 -rwx 720 Mar 01 1993 02:21:30 vlan.dat
16128000 bytes total (10003456 bytes free)

Now rename the configuration file to be used later on.

switch: rename flash:config.text flash:oldconfig.text

To further boot the switch run the boot command, this will start the boot you are used to.

switch: boot

When the switch is booted up, you will realize that the configuration is lost But you are enabled on the switch now and we can recover our old configuration as we kept that in flash with different name.

To recover the old configuration:

Switch# rename flash:oldconfig.text flash:config.text

And now to replace the running configuration with the backup

Switch# copy flash:config.text running-config
Destination filename [running-config]?

Press enter, and you will have your old switch configuration back and you are enabled but remember to change your password now.

I hope this will be informative for you.

Cheers :)

Why 3550 and SMI v/s EMI

Before I discuss difference between SMI and EMI ios on Cisco catalyst switch (3550), lets first talk about a big Question WHY 3350 switch ?

1. First Switch which can be a Router
2. Some other features support like Uplink Fast / Backbone Fast / Rapid STP
3. HUGE bandwidth optimization using Layer-2 and Layer-3 Etherchannel
4. Advance QoS Features

Models

1. 3550-24
2. 3550-48
3. 3550-12T
4. 3550-12G

3550-24 and 48 are either 10-Base, 100-Base or 1000-Base. While 3550-12T provides 10-ports of having speed either 10, 100 or 1000 Base while having 2-GBIC ports which is used for Fiber connectivity. On the other hand 3550-12G provides 10-GBIC ports and two Cat-5 ports of respective speed.

Now Lets talk about the ios that 3550 switch has, it will be either 3550-EMI IOS or 3550-SMI IOS so we should know the difference between these two so that we can decide which ios to go for:

The 3550 is either a Layer-2 or Layer-3 switch, which depends on the software version and feature set that you install. The naming conventions for 3550 images can be any one:

ipbase (Formerly SMI): Cisco IOS IP base image and device manager files. This image has Layer 2+ and basic Layer 3 routing (Static, RIP) features.

ipservices(Formerly EMI): Cisco IOS IP services image and device manager files. This image has Layer 2+ and full Layer 3 features.

ipbasek9: Cisco IOS IP base cryptographic image and device manager files. This image has the Kerberos, Secure Shell (SSH), Layer 2+, and basic Layer 3 routing features.

ipservicesk9: Cisco IOS IP services cryptographic image and device manager files. This image has the Kerberos, SSH, Layer 2+, and full Layer 3 features.


The differences between the two are:

SMI

The SMI image is essentially an L2-only image. However, SMI adds basic L3 functionality to the image. This L3 functionality includes static unicast routing, the Routing Information Protocol (RIP), and other features.

EMI

The EMI image is an L2 image in combination with a full L3 feature set. This feature set includes:
Interior Gateway Routing Protocol (IGRP) and Enhanced IGRP (EIGRP)
Open Shortest Path First (OSPF) Protocol
Border Gateway Protocol Version 4 (BGP4)
Hot Standby Router Protocol (HSRP)
Protocol Independent Multicast (PIM)
Other advanced services

I Hope this will be informative for you !

Cheers :)

Configuring Cisco Router as a DHCP Server

Thank GOD, atlast i have done it.....lolz. I was trying from last couple of days to configure cisco router as a DHCP server but there were some problems but anyway today i have done with that. Here is the step wise configuration of the Lab, may be it will help someone. so here we go!

Note: connect the devices as shown in the figure

The configuration on cisco router to be DHCP server as follow:

SERVER(config)# interface fasethernet 0/0
SERVER(config-if)# ip address 192.168.1.1 255.255.255.0
SERVER(config-if)# no shutdown
SERVER(config-if)# exit

SERVER(config)# ip dhcp excluded-address 192.168.1.1 192.168.1.99
SERVER(config)# ip dhcp pool mypool
SERVER(config)# network 192.168.1.0 255.255.255.0
SERVER(config)# default-router 192.168.1.1
SERVER(config)# dns-server 192.168.1.1

Now the configuration on the client side is just simple

CLIENT_1(config)# do show ip interface brief
CLIENT_1(config)#interface fastethernet 0/0
CLIENT_1(config-if)# ip address dhcp
CLIENT_1(config-if)# no shutdown

Now wait for the log message on console, if not seen don't worry after a while CLIENT_1 should obtained ip from DHCP Server.

CLIENT_1# show ip interface brief
CLIENT_1# ping 192.168.1.1

You can check the DHCP bindings by a command

CLIENT_1# show ip dhcp bindings

The output of my lab for this bindings command is as follow:
IP address Client-ID/ Lease expiration Type
Hardware address
192.168.1.100 0001.4303.C501 -- Automatic
192.168.1.101 0004.9A66.B101 -- Automatic
192.168.1.102 000A.41D2.1543 -- Automatic

The same commands are on CLIENT_2 as we did on CLIENT_1. For pc just check the option (ip configuration......DHCP).

Enjoy it!