Cisco vlans/trunks basic configuration examples

/trunk+navive vlan + encapsulation

interface GigabitEthernet0/15
description xx
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 555
switchport trunk native vlan 555
switchport mode trunk

interface FastEthernet0/9
description yy
switchport trunk allowed vlan 555
switchport mode trunk
spanning-tree portfast
interface FastEthernet0/11
description zz
switchport access vlan 555
switchport mode access
spanning-tree portfast

List of Basic Most Used Network Ports

Most Common Ports:

20 & 21: File Transfer Protocol (FTP)
22: Secure Shell (SSH)
23: Telnet remote login service
25: Simple Mail Transfer Protocol (SMTP)
53: Domain Name System (DNS) service
80: Hypertext Transfer Protocol (HTTP) used in the World Wide Web110: Post Office Protocol (POP3)
119: Network News Transfer Protocol (NNTP)
143: Internet Message Access Protocol (IMAP)
161: Simple Network Management Protocol (SNMP)
194: Internet Relay Chat (IRC)
443: HTTP Secure (HTTPS)
465: SMTP Secure (SMTPS)

1433: Windows SQL Server

Basic Cisco Networking Information

Networking Emulator –

Cisco Reference Manual –

IOS Commands
Privileged Mode
enable – get to privileged mode
disable – get to user mode
enable password <password_here> – sets privileged mode password
enable secret <password_here> – sets encrypted privileged mode password

Setting Passwords
enable secret <password_here> – set encrypted password for privilegedaccess
enable password <password_here>
– set password for privileged access (used when there is no enable secret and when using older software)
Set password for console access:
(config)#line console 0
(config-line)#password <password_here>
Set password for virtual terminal (telnet) access
(password must be set to access router through telnet):
(config)#line vty 0 4
(config-line)#password <password_here>
Set password for auxiliary (modem) access:
(config)#line aux 0
(config-line)#password <password_here>

Configuring the Router
sh running-config –
details the running configuration file (RAM)
sh startup-config –
displays the configuration stored in NVRAM
   setup – Will start the the automatic setup; the same as when you first boot the router
config t – use to execute configuration commands from the terminal
config mem – executes configuration commands stored in NVRAM; copies startup-config to running-config
config net – used to retrieve configuration info from a TFTP server
   copy running-config startup-config – copies saved config in running config (RAM) to NVRAM or “write memory” for IOS under ver.11
   copy startup-config running-config – copies from non-volatile (NVRAM) to current running config (RAM)
   boot system flash <filename_here> – tells router which IOS file in flash to boot from
   boot system tftp – tells router which IOS file on the tftp server to boot from
boot system rom – tell router to boot from ROM at next boot
   copy flash tftp – Copies flash to tftp server
   copy tftp flash – Restores flash from tftp server
   copy run tftp – Copies the current running-config to tftp server
   copy tftp run – Restores the running-config from tftp server

General Commands
no shutdown – (enables the interface)
   reload – restarts the router
sh ver
– Cisco IOS version, uptime of router, how the router started, where system was loaded from, the interfaces the POST found, and the configuration register
sh clock – shows date and time on router
   sh history – shows the history of your commands
sh debug – shows all debugging that is currently enabled
no debug all – turns off all debugging
   sh users – shows users connected to router
   sh protocols – shows which protocols are configured
   banner motd # Your_message # – Set/change banner
hostname <router_name_here> – use to configure the hostname of the router
clear counters  – clear interface counters

Processes & Statistics
   sh processes – shows active processes running on router
sh process cpu
– shows cpu statistics
sh mem
– shows memory statistics
   sh flash – describes the flash memory and displays the size of files and the amount of free flash memory
   sh buffers – displays statistics for router buffer pools; shows the size of the Small, Middle, Big, Very Big, Large and Huge Buffers
   sh stacks – shows reason for last reboot, monitors the stack use of processes and interrupts routines

CDP Commands (Cisco Discovery Protocol uses layer 2 multicast over a SNAP-capable link to send data):
sh cdp neighbor – shows directly connected neighbors
   sh cdp int – shows which interfaces are running CDP
sh cdp int eth 0/0 – show CDP info for specific interface
sh cdp entry <cdp_neighbor_here> – shows CDP neighbor detail
   cdp timer 120 – change how often CDP info is sent (default cdp timer is 60)
cp holdtime 240 – how long to wait before removing a CDP neighbor (default CDP holdtime is 180)
   sh cdp run – shows if CDP turned on
no cdp run – turns off CDP for entire router (global config)
no cdp enable – turns off CDP on specific interface

Miscellaneous Commands
sh controller t1 
– shows status of T1 lines
sh controller serial 1 – use to determine if DCE or DTE device
(config-if)#clock rate 6400 – set clock on DCE (bits per second)
(config-if)#bandwidth 64 – set bandwidth (kilobits)

IP Commands
Configure IP on an interface:
    int serial 0
ip address
int eth 0
ip address 2008.1.1.4

Other IP Commands:
    sh ip route – view ip routing table
    ip route <remote_network> <mask> <default_gateway> [administrative_distance] – configure a static IP route
   ip route <gateway_of_last_resort> – sets default gateway
  ip classless – use with static routing to allow packets destined for unrecognized subnets to use the best possible route
    sh arp – view arp cache; shows MAC address of connected routers
ip address secondary – configure a 2nd ip address on an interface
    sh ip protocol     sh ip interface – Show all IP interfaces
    sh ip interface brief – Show brief overiew of IP interfaces
    sh ip nat translations – Show current IP NAT translations

IPX Commands
Enable IPX on router:
    ipx routing
Configure IPX + IPX-RIP on an int:

    int ser 0
ipx network 4A
Other Commands:
sh ipx route
– shows IPX routing table
    sh ipx int e0 – shows ipx address on int
    sh ipx servers – shows SAP table
    sh ipx traffic – view traffic statistics
    debug ipx routing activity – debugs IPS RIP packets
    debug ipx sap – debugs SAP packets

Routing Protocols
Configure RIP:
    router rip
Other RIP Commands:
debug ip rip
– view RIP debugging info
Configure IGRP:
    router IGRP 200
Other IGRP Commands:
    debug ip igrp events – view IGRP debugging info
    debug ip igrp transactions – view IGRP debugging info

Access Lists (see notes below for details)
sh ip int ser 0 – use to view which IP access lists are applies to which int
sh ipx int ser 0 –
use to view which IPX access lists are applies to which int
sh appletalk int ser 0 –
use to view which AppleTalk access lists are applies to which int
View access lists:
sh access-lists
sh ip access-lists
sh ipx access-lists
sh appletalk access-lists
Apply standard IP access list to int eth 0:
access-list 1 deny
access-list 1 permit any
int eth 0
ip access-group 1 in
Apply Extended IP access list to int eth 0:
access-list 100 deny tcp host host eq 23
access-list 100 deny tcp any eq 80
int eth 0
ip access-group 100 out
Apply Standard IPX access list to int eth 0:
access-list 800 deny 7a 8000
access-list 800 permit -1
int eth 0
ipx access-group 800 out
Apply Standard IPX access list to int eth 0:
access-list 900 deny sap any 3378 -1
access-list 900 permit sap any all -1
int eth 0
ipx access-group 900 out

Wan Configurations (see notes below for more details)

PPP Configuration
encapsulation ppp
ppp authentication <chap_or_pap_here>
ppp chap hostname <routername_here>
ppp pap sent-username <username_here>
sh int ser 0 –
use to view encapsulation on the interface

Frame-Relay Configuration
encapsulation frame-relay ietf – use IETF when setting up a frame-relay network between a Cisco router and a non-Cisco router
frame-relay lmi-type ansi – LMI types are Cisco, ANSI, Q933A; Cisco is the default; LMI type is auto-sensed in IOS v11.2 and up
frame-relay map ip 100 broadcast – if inverse ARP won’t work, map Other IP to Your DLCI # (local)
keepalive 10 – use to set keepalive
sh int ser 0 – use to show DLCI, LMI, and encapsulation info
sh frame-relay pvc – shows the configured DLCI’s; shows PVC traffic stats
sh frame-relay map – shows route maps
sh frame-relay lmi – shows LMI info

Keyboard Shortcuts
   CTRL-P – show previous command
   CTRL-N – show next command
   SHIFT-CTRL-6 – Break


Static and Dynamic Routing

Static Routing – manually assigned by the Admin user entering the routes (Routed Protocols – IP, IPX and AppleTalk)
Dynamic Routing – generated/determined by a Routing Protocol (Routing Protocols – RIP I, RIP II, IGRP, EIGRP, OSPF, NLSP, RTMP)

1) With Dynamic Routing, routers pass information between each other so that routing tables are regularly maintained.
2) The routers then determine the correct paths packets should take to reach their destinations.
3) Information is passed only between routers.
4) A routing domain is called an Autonomous System, as it is a portion of the Internetwork under common admin authority.
5) Consists of routers that share information over the same protocol. Can be split into routing areas.

Basic Network Subneting Info

Subnetting: / / /  (8bits)

128 / 64 / 32 /  16 /  8 / 4 / 2 / 1

2(8) -2 = 254 host available

Class A:

Class B:

Class C:

Division of Subnet mask:

1         1        0       0      0   0    0    0

128 / 64 / 32 /  16 /  8 / 4 / 2 / 1 ( 8 Bits of Device Identifiers 2(8) – 2 = 254

(Network Identifier + Device Identifier)

Network 1 TCP/IP Subnet

Switch  –  (Routing Required)

Network 2 TCP/ip Subnet

Different Subnet cannot speak to each other without routing.