Delete configuration from nvram :
# erase startup-config
# delete vlan.dat

#show flash :
#show startup-config
#show running-config

Router Reset password :

Step 1) Restart router :
#reload
Step 2) when device is starting :
Cntrl + break
(Go to rommon mode)
rommon> confreg 0x2142
rommon> boot
Please wait until device starting
Step 3 ) copy configuration from nvram to running-config :
# copy startup-config running config
Step 4) change username & password :
(Config)# username <name> pass <num>
(Config)# enable secret <num>
(Config)# do write
Step 5) Restart router :
# reload
Step 6) when device is starting :
Cntrl + break
(Go to rommon mode)
rommon> confreg 0x2102
rommon> boot

Time-based ACL :

Time-range config :
(Config)# time-range <name>
(Config-time-range)# periodic <weekdays or daily> <starting time> to <ending time>

Create ACL :
(Config)# ip access-list <type> <name>
(Config-ext-nacl)# permit <protocol> <source address> <wildcard> <Destination address> <wildcard> time-range <name>

CDP Filtering :

Create tlv-list :
(Config)# cdp tlv-list <name>
(Config-tlv-list)# <feature>

Using tlv-list in interfaces :
(Config)# int fa <num>
(Confif)# cdp filter-tlv-list <name>

Trunk 802.1Q : all vlan tagged except vlan 1
Trunk ISL : all vlan tagged
Native vlan by default = vlan 1 (untagged)
Change native vlan :
(Config)# Int fa <num>
(Config)# switchport trunk native vlan <num>

VTP Advertisements :

1- Summary Advertisements

* Every 5 minutes by a VTP server or client to inform neighboring VTP-enabled switches of the current VTP configuration revision number for its VTP domain

*Immediately after a configuration has been made


2- Subset Advertisements :

A subset advertisement contains VLAN information. Changes that trigger the subset advertisement include:

Creating or deleting a VLAN
Suspending or activating a VLAN
Changing the name of a VLAN
Changing the MTU of a VLAN

3- Request Advertisements:

When a request advertisement is sent to a VTP server in the same VTP domain, the VTP server responds by sending a summary advertisement and then a subset advertisement. Request advertisements are sent if:

The VTP domain name has been changed
The switch receives a summary advertisement with a higher configuration revision number than its own
A subset advertisement message is missed for some reason
The switch has been reset

Etherchannel Configuration :

A) Static (Manual) : no auto negotiate


B) Dynamic : auto negotiate


B-1 ) PAGP (Port Aggregation Protocol) ----> Cisco

B-2 ) LACP ----> Standard


Static Config :
(Config)# int ra fa <num>-<num>
(config-if-range)# channel-group <num> mode on

Dynamic Config Help & Config:
active Enable LACP unconditionally
auto Enable PAgP only if a PAgP device is detected
desirable Enable PAgP unconditionally
on Enable Etherchannel only
passive Enable LACP only if a LACP device is detected

Use LACP Protocol :

switch1:
(Config)# int ra fa <num>-<num>
(config-if-range)# duplex auto
(config-if-range)# channel-group <num> mode active

switch2:
(Config)# int ra fa <num>-<num>
(config-if-range)# duplex auto
(config-if-range)# channel-group <num> mode passive


Change Priority In LACP Protocol :
(config)# lacp system-priority priority <num>
By Default = 32,768
When Priority is similar then Lower mac address is better


Use PAGP Protocol :

switch1:
(Config)# int ra fa <num>-<num>
(config-if-range)# duplex auto
(config-if-range)# channel-group <num> mode auto

switch2:
(Config)# int ra fa <num>-<num>
(config-if-range)# duplex auto
(config-if-range)# channel-group <num> mode desirable


new interface created By Channel-group :
(config)# int port-channel <num>

Show Cmds :
#show etherchannel
#show etherchannel load-balance
#show etherchannel summary
#show etherchannel port-channel

HSRP States :

1) Initial: The beginning state. The initial state indicates that HSRP does not run. This
state is entered via a configuration change or when an interface first comes
up.


2) Listen: The router knows the virtual IP address, but the router is neither the active
router nor the standby router. It listens for hello messages from those
routers.


3) Speak: The router sends periodic hello messages and actively participates in the
election of the active or standby router. A router cannot enter speak state
unless the router has the virtual IP address.


4)Standby: The router is a candidate to become the next active router and sends periodic
hello messages. With the exclusion of transient conditions, there is, at most,
one router in the group in standby state.

5)Active :The router currently forwards packets that are sent to the group virtual MAC
address. The router sends periodic hello messages. With the exclusion of
transient conditions, there must be, at the most, one router in the active state
in the group.


HSRP Configuration :

(config)# int vlan <num>
(config-if)# standby <num> ip <> --------> (Virtual ip)
(config-if)# standby <num> priority <num>
(config-if)# standby <num> preempt
(config-if)# standby <num> preempt delay minimum <num>
(config-if)# standby <num> authentication md5 key-string <num>
(config-if)# standby <num> timers <num> ---> Hello <num> ----> Hold
(config-if)# standby <num> version <num>
(config-if)# standby <num> track fa|gig|... <num>


Default Timers = Hello time 3 sec, hold time 10 sec
HSRP Reserved MAC Address : 0000.0c07.acXX
Default Priority = 100

Show Cmds :
#show standby
#show standby brief

Advanced Redistribution

Basic redistribution routers :

(Config)# router eigrp <num>
(Config-router)# no auto summary
(Config-router)# Redistribute ospf <num> metric <num>

(Config)# router ospf <num>
(Config-router)# redistribute eigrp <num> subnets metric <num>