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Configuring Cisco Switch 3750G POE

This is a set of running notes on configuring a Cisco 3750G POE Switch.  It's very very messy and is meant for me to remember the ins and outs of doing this.  Along the way, it could help someone else too.

First use a console connection to your switch.  The console is unaffected by what we do on the ports so for initial configuration, this is what is recommended.  You'll need a DB9 to RS-232 Cable however some wiring of the DB9 may be needed so it is highly recommended you do that.  Search for the pin placements of a DB9 to an RS-232 for a Cisco switch on this blog.  If all connected well, you'll be rewarded with a nice cold busybox prompt.  Cisco default settings are:

Bits per sec    :  9600 
Data bits       :     8 
Parity          :  none 
Stop bits       :     1 
Flow control    :  none 

In windows go to Device Manager vi a navigation gauntlet to find the COM? port you need for putty while in linux run ls -altri /dev/ttyUSB* to determine the serial port (If you're using a Serial to USB RS-232).  Your reward will be:

mdscisco01>
mdscisco01>

This is good.  On to the fun stuff.  At this point your best friend is the ? charater.  It will show you the help with which you can remember things and get started on.  Turn on previlidged commands.  We'll do most of our work through here:

mdscisco01>enable
mdscisco01#

Not bad.  Now we'll use this list of commands to get by and configure it the way we like.

mdscisco01#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
mdscisco01(config)#

mdscisco01(config)#int GigabitEthernet1/0/28
mdscisco01(config-if)#

mdscisco01#show ip int brief
Interface              IP-Address      OK? Method Status                Protocol
Vlan1                  192.168.0.3     YES NVRAM  up                    down
GigabitEthernet1/0/1   unassigned      YES unset  down                  down

mdscisco01#sh vlan

create some VLAN's that we can use later (not necessary but handy)

mdscisco01(config)#vlan 1,40-50,60-70,100,200

well never mind so let's remove these VLAN's  (At least now you know the syntax for it.  Later we will enable them on a port range.):

mdscisco01(config)#no vlan 40-50,60-70,100,200
mdscisco01(config)#

Set an IP / Gateway on VLAN 1 on the switch (Unremovable VLAN)

mdscisco01#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
mdscisco01(config)#int vlan 1
mdscisco01(config-if)#ip address 192.168.0.3 255.255.255.0
mdscisco01(config-if)#no shut
mdscisco01(config-if)#
01:00:25: %LINK-3-UPDOWN: Interface Vlan1, changed state to up
mdscisco01(config-if)#end
mdscisco01#
01:00:31: %SYS-5-CONFIG_I: Configured from console by console
mdscisco01#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
mdscisco01(config)#int vlan 1
mdscisco01(config-if)#ip default-gateway 192.168.0.1
mdscisco01(config)#ip default-gateway 192.168.0.1
mdscisco01(config)#end
mdscisco01#
01:02:36: %SYS-5-CONFIG_I: Configured from console by console
mdscisco01#show int vlan 1
Vlan1 is up, line protocol is down
  Hardware is EtherSVI, address is 001c.57ae.f840 (bia 001c.57ae.f840)
  Internet address is 192.168.0.3/24
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive not supported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input never, output 00:02:24, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts (0 IP multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     22 packets output, 1459 bytes, 0 underruns
     0 output errors, 1 interface resets
     0 output buffer failures, 0 output buffers swapped out
mdscisco01#

Next we will test the connectivity of our switch to the rest of the network. (Second comment UPDOWN is Amber light and third UPDOWN is Green light on the switch ports to which a cable is connected. )

mdscisco01#
01:06:42: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/13, changed state to up
01:06:43: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/13, changed state to up
mdscisco01#
01:07:11: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to up
mdscisco01#

And validate the ping to some of the equipment you have:

 

mdscisco01#ping 192.168.0.152
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.152, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/203/1007 ms
mdscisco01#

Now let's set the password to enable SSH / Telnet Login:

mdscisco01(config)#enable secret <halbhalb>
mdscisco01(config)#enable password <halbhalb>

The enable password you have chosen is the same as your enable secret.
This is not recommended.  Re-enter the enable password.

mdscisco01(config)#
mdscisco01(config)#
mdscisco01(config)#enable password <blahblah>
mdscisco01(config)#end

Sometimes an interface misbehaves so we can shut it down until we investigate what's wrong:

mdscisco01#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
mdscisco01(config)#int gigabitethernet1/0/3
mdscisco01(config-if)#
mdscisco01(config-if)#shut
mdscisco01(config-if)#
02:45:45: %LINK-5-CHANGED: Interface GigabitEthernet1/0/3, changed state to administratively down
02:45:46: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/3, changed state to down
mdscisco01(config-if)#
mdscisco01(config-if)#
mdscisco01#show interface gigabitethernet1/0/3
GigabitEthernet1/0/3 is administratively down, line protocol is down (disabled)
  Hardware is Gigabit Ethernet, address is 001c.57ae.f803 (bia 001c.57ae.f803)
  MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Auto-duplex, Auto-speed, media type is 10/100/1000BaseTX
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input never, output 00:05:26, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts (0 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     26815 packets output, 3035941 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 PAUSE output
     0 output buffer failures, 0 output buffers swapped out
mdscisco01#

If your configuration is working, don't forget to save it:

mdscisco01#copy running-config startup-config
Destination filename [startup-config]?
Building configuration…
[OK]
mdscisco01#

If you get:

Password required, but none set

It's time to set a password for your Cisco switch:

mdscisco01#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
mdscisco01(config)#aaa
% Incomplete command.

mdscisco01(config)#aaa new-model
mdscisco01(config)#aaa authentication login default local

mdscisco01(config)#aaa authentication enable default enable
mdscisco01(config)#username <USER> password <SECRET>
mdscisco01(config)#enable secret <USER>
mdscisco01(config)#end
mdscisco01#
03:51:16: %SYS-5-CONFIG_I: Configured from console by console
mdscisco01#

And then you need to go back above and enable secret <SECRET> followed by enable password <PASSWORD> 

To discover IP's mapped to their MAC addresses, use these commands:

mdscisco01# show mac-address-table
mdscisco01# show arp
mdscisco01# sh ip arp
mdscisco01#sh int gig 1/0/2   # Short Form

Good stuff!  

Cheers,
TK

 

 

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