CISCO 默認配置簡述

  Hi,
however its reasonably to see official cisco IOS definition of these 
commands
I try to write some notes from my head and cco.


> no service pad
switch off pad protocol on the router.

Packet Assembly and Disassembly (PAD) is used for sending and
receiving "raw" data over IP networks. The modem takes care of
establishing IP network connections, as well as the encapsulation
of data within UDP or TCP packets. This eliminates the need for a
TCP/IP stack running on the host device.

> service timestamps debug uptime
switch on the service of timestamping each debug log (when you type any 
debug command) the router produces.
But in opposed to "datetime" you use "uptime".

> service timestamps log datetime

The same what above, but applied to regular log data.

> service password-encryption
switch on cisco algorithm to hide clear text password (enable, telnet etc)
and instead show this password as a meaningless string (ggtrg9543ygtrhth).
In opposed to hash algorithm (e.g. MD5) its eassy to decipher this string to 
original password.

> service sequence-numbers

To enable visible sequence numbering of system logging messages, use the 
service sequence-numbers command in global configuration mode.
Each system status messages logged in the system logging process have a 
sequence reference number applied. This command makes that number visible by 
displaying it with the message. The sequence number is displayed as the 
first part of the system status message.

For example:

000066: .Mar 22 15:35:57 PST: %SYS-5-CONFIG_I: Configured from console by 
console

> no aaa new-model
You do not going to use AAA model (authentication, authorization and 
accounting).


> clock timezone UTC 1
You set UTC time zone.
UTC is Coordinated Universal Time.
"1" after UTC means one hour shift, i.e. this is UTC+1=CET (and some others, 
BST, IST, WEST)
CET is Central European Time.


> clock summer-time UTC recurring last Sun Mar 2:00 last Sun Oct 3:00

Configure the system to automatically switch to summer time (daylight saving 
time).

> ip subnet-zero
You want to save and use the first subent (subnet zero).
This sybnet has the same network address what main network (the subnetted 
one) but longer subnet mask
For example:

10.0.0.0/8 is main network
10.0.0.0/24 is subnet zero of this network.
With the commands "no ip subnet-zero" You are not allowed to use this 
subnet.
Then You can use 10.0.1.0/24 subnet as the first usable subnet.


> no file verify auto

switch off automatic verification of cisco files.
When You copy some files to your router its safe to verify theirs control 
sum.
For example:

copy /verify tftp://10.1.1.1/jdoe/c7200-js-mz disk0:
verify disk0:c7200-js-mz
reload /verify

With this feature switch on You do not need to do this, insted router do 
this automatically.


> spanning-tree mode pvst

You want to run pvst (per-Vlan spannig tree) mode od spanning tree protocol. 
It means that in every vlan throughout your switched network
seperate instance of STP frames will be running. Its good only for small 
number of vlans. In other cases its safe to use MST (multiple spanning tree)

> spanning-tree extend system-id

Enable the extended system ID feature on a chassis that supports 1024 MAC 
addresses.Releases 12.1(13)E and later support chassis with 64 or 1024 MAC 
addresses. For chassis with 64 MAC addresses, STP uses the extended system 
ID plus a MAC address to make the bridge ID unique for each VLAN.

> vlan internal allocation policy ascending
It configures the Internal Vlan allocation policy. You can choose between 
"ascending" and "descending".
Enter the ascending keyword to allocate internal VLANs from 1006 and up.
Enter the descending keyword to allocate internal VLAN from 4094 and down.
1006-4094 - this is extended range of etherenet-only vlans, they are not 
propagated by vtp protocol.


> control-plane

switch on control plane policing.
The Control Plane Policing feature allows users to configure a quality of 
service (QoS) filter that manages the traffic flow of control plane packets 
to protect the control plane of Cisco IOS routers and switches against 
reconnaissance and denial-of-service (DoS) attacks. In this way, the control 
plane (CP) can help maintain packet forwarding and protocol states despite 
an attack or heavy traffic load on the router or switch.

***
More about these you can find on cisco.com in public area without CCO 
access.

http://www.cisco.com/univercd/home/home.htm


Regards,
Wlodek.