CISCO Router Commands

Basic

# write = copy running-config startup-config
# write erase

Ctrl-R = refresh line Ctrl-Z = end Ctrl-A = beginning of a line Ctrl-E = end of the line Ctrl-D = Delete previous char Ctrl-W = delete previous word

IP Address, subnetting

Class A: starts with 0x0xxxxxxx (0-127), 127=128-1 Class B: starts with 0x10xxxxxx (128-191), 191 = 128+64-1 Class C: starts with 0x110xxxxx(192-223), 223 = 128+64+32-1 Class D: starts with 0x1110xxxx(224-239), 239= 128+64+32+16-1 Class E: starts with 0x11110xxx(240-255) not used.

List DHCP lease and clients

show dhcp server
show dhcp lease
show ip dhcp binding

NAT

config t
interface gigabitethernet 0/1
ip nat inside
end

# forward ssh
ip nat inside source static tcp 192.168.10.1 22 interface BVI3 22
# turn it off
no ip nat inside source static tcp 192.168.10.1 22 interface BVI3 22

SVI - Switch Virtual Interface

There is no physical interface for the VLAN and the SVI provides the Layer 3 processing for packets from all switch ports associated with the VLAN. - There is one-to-one mapping between a VLAN and SVI

# int vlan 1
# ip address 192.168.0.254 255.255.255.0
# int vlan 2
# ip address 192.168.1.254 255.255.255.0

# ip default gateway 192.168.1.254

IP Routing

# ip routing 
# no ip routing

Static Routing

# ip route 0.0.0.0 0.0.0.0 192.168.1.5
# ip route 192.168.0.0 255.255.255.0 192.168.2.5
# show ip route 192.168.0.1

RIPv2

# conf t
# router rip
# version 2
# no auto-summary
# network 192.168.1.0
# network 192.168.3.0

Router on a Stick, sub-interfaces

On the switch, configure the link to router as trunk

# switchport trunk encapsulation dot1q
# switch mode trunk
# show interfaces trunk

On the router interface, remove IP on the main interface

# int fa0/0
# no ip address
# int fa0/0.2
# encapsulation dot1Q 2
# ip address 192.168.1.1 255.255.255.0
# int fa0/0.4
# encapsulation dot1Q 4
# ip address 192.168.3.1 255.255.255.0
# show ip route