Switch Configuration

 Swithch>show ? ----Lists all commands. If you enter show? It will shows just "show".

If yo type "enable" it will change to Switch# from Swich>

Switch#debug ?

Switch#configre ?

Switch#configure terminal ?

Switch#conf t

Swtich(config)#hostname HAL

HAL(config)#hostname SW1

SW1(config)#^Z

SW1#show config

SW1#wr

SW1#conf t

SW1(config)#no service timestamps

SW1(config)#line console 0

SW1(config-line)#logging ?

SW1(config-line)#exec-timeout 0?

SW1(config-line)#exec-timeout 0 0 --->This negates time out. We will not be kicked out ever. 


VLAN: It helps us group hosts by department, security clearances, locations, etc. It also prevents broadcast storms by limiting the scope of broadcasting. 


HOST_1#pintg10.1.1.2 --->only sends 5

HOST_1#ping

Protocol [ip]:

Target IP address: 10.1.1.2

Repeat count [5]:10

If you enter wrong IP with 1 million ping, you need to type ctrl shift 6 to get out. 


SW1#show vlan

SW1#show cdp neighbor

SW1#show cdp neigh detail

SW1(config)#int fast 4/0/18

SW1(config-if)#switchport mode access vlan 24

Trunking: It is the process of creating a logical path between two physically connected switched, allowing frames to flow between them. 

SW1#show int trunk

SW1# conf t

SW1(config)#int fast 4/0/23

SW1(config-if)#switchport mode dynamic desirable

SW1#show int trunk

Port           Mode               Encapsulation          Status                Native vlan

fa4/0/23    desirable          n-isl                          trunking            1


Trunking Modes:

SW1#conf t

SW1(config)#int fast 4/1/1

SW1(config-if)#switchport mode dynamic

SW1#show int fast 4/1/1 switchport

Name:Fa4/0/1

Operational Mode: static access

Pruning VLANs Enabled: 2-1001

Administrative mode: dynamic auto

SW2#conf t

SW2(config)#int fast 2/0/1

SW2(config-if)#switch port mode dynamic desirable

If you see Line protocol down, wait for a couple of minutes to make sure it doesn't stay up. 


Dynamic Trunking Protocol (DTP): It handles the actual trunk negotiation workload. When this Cisco-proprietary point-to-point protocol is in action, it attempts to negotiate a trunk with the remote port. As with everything in networking, DTP comes with a cost. A port running DTP will send DTP frames out every 30 seconds. 

SW2#conf t

SW2(config)#int fast 2/0/1

SW2(config-if)#sswitchport negotiate

Command rejected: Conflict between 'negotiate' and 'dynamic' status.

SW2#debug dtp all

To stop debug, tap up arrow twice.

SW2#debug dtp packets

Passive dynamic trunking with switchport mode dynamic auto. This means the port will trunk, but the other side has to initiate the process. If the remote port is in desirable or on mode, you've got to trunk. If both sides are in auto, no trunk will form as each end of the trunk is waiting for the other side to get that party started. 

Per-VLAN Traffic Filtering: 

SW1(config-if)#switchport trunk allowed vlan except 20

SW1(config-if)#switchport trunk allowed vlan all


VLAN.DAT File: Delete this file to delete the vlan 

SW1#write erase

reload

Switch>en

Switch#show vlan flash

Directory of flash: 

Swith#del vlan.dat
























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