Cisco Tips & Tricks

January 2, 2011

2010 in review

Filed under: Router — ciscotips @ 6:55 am

The stats helper monkeys at WordPress.com mulled over how this blog did in 2010, and here’s a high level summary of its overall blog health:

Healthy blog!

The Blog-Health-o-Meter™ reads Wow.

Crunchy numbers

Featured image

A helper monkey made this abstract painting, inspired by your stats.

The Louvre Museum has 8.5 million visitors per year. This blog was viewed about 150,000 times in 2010. If it were an exhibit at The Louvre Museum, it would take 6 days for that many people to see it.

In 2010, there were 4 new posts, growing the total archive of this blog to 95 posts.

The busiest day of the year was March 18th with 628 views. The most popular post that day was How to block skype.

Where did they come from?

The top referring sites in 2010 were google.com, google.co.in, blog.ioshints.info, stumbleupon.com, and fa.wikipedia.org.

Some visitors came searching, mostly for route summarization, ospf cost, eigrp k values, ospf load balancing, and subnet mask cheat sheet.

Attractions in 2010

These are the posts and pages that got the most views in 2010.

1

How to block skype June 2006
48 comments

2

Route Summarization May 2006
17 comments

3

Configuring a Cisco router as a terminal server June 2006
29 comments

4

Turning the router in to Packet sniffer May 2006
5 comments

5

CCIE notes for EIGRP July 2006
20 comments

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December 2, 2010

IPv6 Experts

Filed under: IPv6, Router — ciscotips @ 7:14 pm

Came across an excellent website for IPv6

www.theipv6experts.net

August 7, 2009

Undocumented IOS commands

Filed under: ccie, cisco, Router — ciscotips @ 1:01 am

Undocumented IOS commands

 

 

Here you can find a collection of undocumented (not on Cisco Dokumentation CD or in online help) IOS commands:

  • csim
  • show interface switching
  • show ip ospf statistics
  • show ip ospf m
  • show ip ospf events
  • debug ip ospf monitor
  • no service password-recovery
  • ttcp
  • if-con
  • no snmp-server sparse-tables
  • who
  • show region
  • ps -c
  • quit
  • test aaa group radius
  • show snmp
  • set option flowcontrol

 

 

 


With the command csim you can emulate a voice call. ItŽs like sombody calls the specified number. Usefull, if you donŽt have physically access to telephone:

Sucessfull call:

wg1r1#csim start 089150
csim: called number = 089150, loop count = 1 ping count = 0
csim err csimDisconnected recvd DISC cid(21)
csim: loop = 1, failed = 1
csim: call attempted = 1, setup failed = 1, tone failed = 0

 

wg1r1#csim start 089151
csim: called number = 089151, loop count = 1 ping count = 0

csim err:csim_do_test Error peer not found

 


With show interface switching you can see in detail, which protocols are process, fast or elsewhere switched. ItŽs helpfull for traffic engineering:

wg1r1#sh interfaces switching
Ethernet0/0

Throttle count          0
Drops         RP          0         SP          0
SPD Flushes   Fast        0        SSE          0
SPD Aggress   Fast        0
SPD Priority  Inputs      5700     Drops        0

Protocol       Path    Pkts In   Chars In   Pkts Out  Chars Out
Other       Process       8821     983982       7806     468360
Cache misses                 0
Fast                         0          0          0          0
Auton/SSE                    0          0          0          0
IP          Process      32228    3339712       5786     611402
Cache misses                 0
Fast                     92667    8980418     133414  189720295
Auton/SSE                    0          0          0         0
DEC MOP     Process          0          0        130      10010
Cache misses                 0
Fast                         0          0          0          0
Auton/SSE                    0          0          0          0
ARP         Process       6440     386380        195      11700
Cache misses                 0
Fast                         0          0          0          0
Auton/SSE                    0          0          0          0
CDP         Process          0          0       1302     404922
Cache misses                 0
Fast                         0          0          0          0
Auton/SSE                    0          0          0          0

 

 


With show ip ospf statistics you get detail informations about OSPF SPF. You can see the reasons for SPF and the calculation times:

London#show ip ospf statistic
Area 0: SPF algorithm executed 15 times

SPF calculation time
Delta T Intra D-Intra Summ D-Summ Ext D-Ext Total Reason
00:45:02 32 0 0 0 0 0 36 R,
00:41:00 28 0 0 0 0 0 28 R, N,
00:40:50 28 0 0 0 0 0 28 R,
00:38:13 28 0 0 0 4 0 32 R, X
00:34:18 24 0 0 0 4 0 32 R, N,SN,SA,X
00:07:37 24 0 0 0 0 0 36 R,
00:05:18 308 0 4 0 28 0 356 R,
00:04:05 24 0 0 0 4 0 28 R,
00:01:31 24 0 4 0 0 0 36 R,
00:01:21 24 0 0 4 0 0 36 R,


With debug ip ospf monitor you can monitor the OSPF SPF.

London#deb ip ospf monitor 

OSPF spf monitoring debugging is on
2d04h: OSPF: 192.168.181.2 address 192.168.181.193 on TokenRing0 is dead, state DOWN
2d04h: OSPF: Schedule SPF in area 0
Change in LS ID 0.0.0.0, LSA type R,
2d04h: OSPF: schedule SPF: spf_time 0ms wait_interval 187489656s
2d04h: %SYS-5-CONFIG_I: Configured from console by console
2d04h: OSPF: Start redist-scanning
2d04h: OSPF: Scan for redistribution
2d04h: OSPF: End scanning, Elapsed time 0ms
2d04h: %LINK-5-CHANGED: Interface TokenRing0, changed state to administratively down
2d04h: OSPF: Begin SPF at 0xB2CF100ms, process time 360ms
2d04h: spf_time 0ms, wait_interval 187489656s
2d04h: OSPF: End SPF at 0xB2CF120ms, Total elapsed time 32ms
2d04h: Intra:24ms, Inter: 0ms, External: 0ms

 


I found that in 12.0(20) Enterprise that show ip os monitor is not available but show ip os m is. Show ip os events is the undocumented command:

tr-Albany-2#sh ip os monitor
^
% Invalid input detected at ‘^’marker.

Rtr-Albany-2# sh ip os m
AS System 1
Maxage delete timer due in NEVER
Rtr-Albany-2#sh ip os events
1 17844 Timer Exp: if_ack_delayed 0x616DDE08
2 40152 Generic: ospf_redist_callback 0x61735760
3 59800 Timer Exp: if_ack_delayed 0x616DD3C8
4 88664 Timer Exp: if_ack_delayed 0x616DDE08
5 88672 Timer Exp: if_ack_delayed 0x616DD3C8
6 100184 Generic: ospf_redist_callback 0x61735760
7 126576 Timer Exp: if_ack_delayed 0x619621AC
8 160216 Generic: ospf_redist_callback 0x61735760
9 164976 Timer Exp: if_ack_delayed 0x616DDE08
10 189256 Timer Exp: if_ack_delayed 0x616DD3C8
….
90 534184 Timer Exp: nbr_retrans_lsa 0xC0A8E425
91 534184 Timer Exp: nbr_retrans_lsa 0xC0A8FC13
92 534188 Timer Exp: nbr_retrans_lsa 0xC0A8FC04

Rtr-Albany-2#

Many thanks for this command goes to Paul.

 


Disable Password Recovery or ROM Monitor Access:

#sh run
Building configuration…
Current configuration:
!
Version 12.1
!
no service password-recovery
!

#rel
Proceed with reload? [confirm]

.Feb 9 12:57:24.013: %SYS-5-RELOAD: Reload requested
System Bootstrap, Version 11.3(2)XA4, RELEASE SOFTWARE (fc1)
Copyright (c) 1999 by cisco Systems, Inc.
TAC:Home:SW:IOS:Specials for info

pressed: 

PC = 0xfff0bba8, Vector = 0x500, SP = 0x680127c8
C2600 platform with 49152 Kbytes of main memory

PASSWORD RECOVERY FUNCTIONALITY IS DISABLED 

PC = 0xfff14dfc, Vector = 0x500, SP = 0x80004864
PC = 0xfff14e08, Vector = 0x500, SP = 0x80004864
PC = 0xfff14df8, Vector = 0x500, SP = 0x80004374
program load complete, entry point: 0x80008000, size: 0x8b9c04

Cisco Internetwork Operating System Software
IOS ™ C2600 Software (C2600-IS-M), Version 12.1(3a)T4, RELEASE SOFTWARE (fc1)

 


Start a TCP data server/receiver for TCP performance testing between two Cisco 7500 router:

sh ver
Cisco Internetwork Operating System Software
IOS ™ RSP Software (RSP-JSV-M), Version 12.0(7), RELEASE SOFTWARE (fc1)

Router#ttcp
transmit or receive [receive]: transmit
Target IP address: 1.1.1.1
perform tcp half close [n]:
send buflen [8192]:
send nbuf [2048]:
bufalign [16384]:
bufoffset [0]:
port [5001]:
sinkmode [y]:
buffering on writes [y]:
show tcp information at end [n]:

ttcp-t: buflen=8192, nbuf=2048, align=16384/0, port=5001 tcp -> 1.1.1.1
%Connect failed: Destination unreachable; gateway or host down

Router#ttcp
transmit or receive [receive]:
perform tcp half close [n]:
receive buflen [8192]:
bufalign [16384]:
bufoffset [0]:
port [5001]:
sinkmode [y]:
rcvwndsize [4128]:
delayed ACK [y]:
show tcp information at end [n]:

ttcp-r: buflen=8192, align=16384/0, port=5001
rcvwndsize=4128, delayedack=yes tcp

Many thanks for this command goes to Thomas Moyses.

 


On Cisco 7500 you can connect you to the VIP boards for VIP commands (memory, cpu,etc.)

Router#if-con 2 con
Entering CONSOLE for VIP2 2
Type “^C^C^C” or “if-quit” to end this session

VIP-Slot2>
VIP-Slot2>?
Exec commands:
clear Reset functions
disable Turn off privileged commands
disconnect Disconnect an existing network connection
enable Turn on privileged commands
exit Exit from the EXEC
help Description of the interactive help system
lock Lock the terminal
login Log in as a particular user
logout Exit from the EXEC
name-connection Name an existing network connection
ping Send echo messages
resume Resume an active network connection
set Set system parameter (not config)
show Show running system information
systat Display information about terminal lines
terminal Set terminal line parameters
traceroute Trace route to destination
where List active connections

VIP-Slot2>en
VIP-Slot2#sh ver
Cisco Internetwork Operating System Software
IOS ™ VIP Software (SVIP-DW-M), Version 12.0(7), RELEASE SOFTWARE (fc1)
Copyright (c) 1986-1999 by cisco Systems, Inc.
Compiled Wed 13-Oct-99 22:05 by phanguye
Image text-base: 0x60010920, data-base: 0x60224000

ROM: System Bootstrap, Version 11.1(11368) [pgreenfi 17], INTERIM SOFTWARE

VIP-Slot2 uptime is 10 minutes
System restarted by power-on
Running default software

cisco VIP2 (R4700) processor (revision 0x02) with 8192K bytes of memory.
Processor board ID 00000000
R4700 processor, Implementation 33, Revision 1.0 (512KB Level 2 Cache)
4 Ethernet/IEEE 802.3 interface(s)
1 FastEthernet/IEEE 802.3 interface(s)

Configuration register is 0x0
VIP-Slot2#?
Exec commands:
cd Change current directory
clear Reset functions
clock Manage the system clock
configure Enter configuration mode
copy Copy from one file to another
debug Debugging functions (see also ‘undebug’)
delete Delete a file
dir List files on a filesystem
disable Turn off privileged commands
disconnect Disconnect an existing network connection
enable Turn on privileged commands
exit Exit from the EXEC
help Description of the interactive help system
lock Lock the terminal
login Log in as a particular user
logout Exit from the EXEC
more Display the contents of a file
name-connection Name an existing network connection
no Disable debugging functions
ping Send echo messages
pwd Display current working directory
reload Halt and perform a cold restart
resume Resume an active network connection
send Send a message to other tty lines
set Set system parameter (not config)
setup Run the SETUP command facility
show Show running system information
systat Display information about terminal lines
terminal Set terminal line parameters
test Test subsystems, memory, and interfaces
traceroute Trace route to destination
undebug Disable debugging functions (see also ‘debug’)
where List active connections
write Write running configuration to memory, network, or terminal

VIP-Slot2#

Many thanks for this command goes to Thomas Moyses.

 


Router(config)# no snmp-server sparse-tables 

Get the complete SNMP MIB table. On controller interface you get without this command e.g. no out bytes counter. With this commands you get every object with SNMP get-next.

 


who is a alias for show user.

Router#who
Line User Host(s) Idle Location
* 0 con 0 idle 00:00:00
1 aux 0 idle 00:01:19


Get more detail IOS informations:

Router#sh region
Region Manager:

Start End Size(b) Class Media Name


0x02700000 0x02FFFFFF 9437184 Iomem R/W iomem
0x60000000 0x60FFFFFF 16777216 Flash R/O flash
0x80000000 0x826FFFFF 40894464 Local R/W main
0x80008088 0x8071A2A3 7414300 IText R/O main:text
0x8071A2A4 0x8097FD93 2513648 IData R/W main:data
0x8097FD94 0x80A4E0CF 844604 IBss R/W main:bss
0x80A4E0D0 0x826FFFFF 30089008 Local R/W main:heap

Many thanks for this command goes to Thomas Moyses.

 


router> ps -c

Will list the process on the router in a “better” way then show process.

Many thanks for this command goes to Thomas Surber.

 


leaving a telnet session: normally with “exit” or “ex”.
do this very fast with “q” (quit)

Many thanks for this command goes to Peter Schmid.

 


test aaa group radius toto titi

To test radius on one router.

CISCO AS5800: This command allow to connect directly to the DSC IOS card from the router Shelf of the
AS5800

dsip con slave “Slot # of the DSC”
ex: dsip con slave 12

Many thanks for this commands goes to Serge Baikoff.

 


These commands have been found in a Cisco 3640 router using the version 12.1(6). It’s very posible that some of these commands are not avalaible in older versions.

— show ip ftp-username

Show the name of the user configured with the comand “ip ftp username”.

–show ip ftp-password

Display the password configured with the command “ip ftp passwword”

— show ip spd

I don’t know the function of this command, but it looks as folow:

sh ip spd
Current mode: normal.
Queue min/max thresholds: 73/74, Headroom: 100
IP normal queue: 0, priority queue: 0.
SPD special drop mode: none

— show ip ospf timers lsa

Show the ospf lsa timers and its output is:

sh ip ospf timers lsa

OSPF Router with ID (215.224.32.13) (Process ID 1)

Group size 5, Head 0, Search Index 4, Interval 240 sec
Next update due in 00:00:15
Current time 64496
Index 0 Timestamp 64511
Index 1 Timestamp 64768
Index 2 Timestamp 65014
Index 3 Timestamp 65258
Index 4 Timestamp 65509

Failure Head 0, Last 0 LSA group failure logged

— show ip eigrp sia-statistics

I don’t know the meaning of this command. When it’s typed shows no useful information:

sh ip eigrp sia-statistic

Many thanks for this command goes to Atreides.

 


Here’s some additional hidden cisco IOS command for debugging ATM on a PA-A3. You need to connect to the VIP first and be in enable mode: (I guess this one is double hidden, first the if-con and then the test atmdx)

syntax: test atmdx PAslotnr (0 or 1)

7507#if-con 0
Console or Debug [C]: c
Entering CONSOLE for VIP2 R5K 0
Type “^C^C^C” or “if-quit” to end this session

VIP-Slot0>enable
VIP-Slot0#test atmdx 0

Main:
1 – VC test
2 – Rx SAR
3 – Tx SAR
q – Quit
Select option : 1

Test VC Section:
1 – Show vc
2 – Show vc statistics
3 – Change vc
q – Quit
Select option : 2
Enter vc number or -1 for all : -1
vcd 1: in_pkts 4, in_drops 0, out_pkts 4, out_drops 0
crc32 0, timeout 0, oversized 0
vcd 2: in_pkts 1, in_drops 0, out_pkts 1, out_drops 0
crc32 0, timeout 0, oversized 0
vcd 3: in_pkts 28, in_drops 0, out_pkts 21, out_drops 0
crc32 0, timeout 0, oversized 0
vcd 4: in_pkts 1, in_drops 0, out_pkts 1, out_drops 0
crc32 0, timeout 0, oversized 0

Many thanks for this commands goes to Rogger Schobben.

 


Tested on 12.22T:

sh snmp host
sh snmp notif
test aaa group policy accounting WORD
test aaa group policy authorization WORD
test aaa group policy authentication WORD
test aaa group priviliges authentication WORD (same for accounting and auth)

In fact there’s a bunch of other stuff you can do behind test aaa group. If you type “a” behind this f.ex., you will also see incomplete command.

Many thanks for this commands goes to Filip Waeytens.

 


If you are overrunning the buffers on ports, at a Cat6500 enable (global) mode, we can enable flow control between the two ASICs on the 6348 card (HW MSFC2) using the command

set option flowcontrol enable

This should help with the out-discards. It may clear it up and it may not. If it doesn’t, you will need more to either create an etherchannel to the router or move to a higher bandwidth connection. The command set option flowcontrol enable allows the COIL ASIC to pass traffic to the Pinnacle ASIC for buffering assistance when the COIL ASIC is overloaded with traffic.

Many thanks for this commands goes to Renato Vilela de Magalháes.

 


bgp common-administration

bgp dynamic-med-interval

bgp process-dpa

clear ip eigrp [as] event Clear IP-EIGRP event logs

clear ip eigrp [as] logging Stop IP-EIGRP event logging

config overwrite

debug dialer detailed

debug ip packet … dump Outputs a hex & ASCII dump of the packet’s contents

debug isdn code

debug sanity

if-con attach to a vip console

if-cons

ip forwarding

ip forwarding accounting

ip forwarding accounting adjacency-update

ip forwarding accounting non-recursive

ip forwarding accounting per-prefix

ip forwarding accounting prefix-length

ip forwarding switch

ip forwarding traffic-statistics

ip forwarding traffic-statistics load-interval

ip forwarding traffic-statistics update-rate

ip igmp

ip igmp immediate-leave

ip igmp immediate-leave group-list

ip local-pool

ip ospf-name-lookup

ip slow-converge

ip spd

ip spd mode

ip spd mode aggressive

ip spd queue

ip spd queue max-threshold

ip spd queue min-threshold

memory scan Parity check for 7500 RSPs

modem-mgmt csm debug-rbs

no service password-recovery

service internal

set destination-preference

show alignment

show asp

show caller

show caller ip

show chunk

show chunk summary

show controller vip log

show controller vip tech

show fib

show fib drop

show fib interface

show fib interface detail

show fib interface loopback

show fib interface null

show fib interface statistics

show fib interface vlan

show fib linecard

show fib linecard detail

show fib not-cef-switched

show fib not-fib-switched

show hardware

show idb

show interface statis

show interface switching

show interfaces stat

show interface stat

show interfaces switching

show int switching

show ip eigrp event [as] [start# end#] IP-EIGRP Events

show ip eigrp sia-event [as] [start# end#] IP-EIGRP SIA event

show ip eigrp timers [as] IP-EIGRP Timers

show ip ospf bad-checksum

show ip ospf delete

show ip ospf delete-list

show ip ospf ev

show ip ospf events

show ip ospf maxage

show ip ospf maxage

show ip ospf statistics

show isdn active

show isdn history

show list

show list nonempty

show llc

show media

show media access-lists

show modem mapping

show parity

show parser

show parser links

show parser modes

show parser unresolved

show profile

show profile detail

show profile terse

show refuse-message

show region

show region address

show rsh

show rsh-disable-commands

show rsp

show slip

show slot

show snmp mib

show sum

show timers

snmp-server priority low

test crash makes the router crash

test ipc misc

test mbus power

ttcp

 

 

router bgp …

bgp redistribute-internal

Usage:

Redistributing BGP into another protocol only redistributes E-BGP routes. Using this command in the BGP configuration will also redistribute I-BGP routes in the other routing-protocol.

 

Source:-http://www.uniberg.com/cisco/undocumented/68.html?session=9c97cccb7190a2eb0f1d0c49d40703c3

February 8, 2009

BGP at 18

Filed under: bgp, ccie, cisco, Router — ciscotips @ 11:49 pm

 

October 27, 2008

Compute an access-list to match even or odd networks

Filed under: Access-lists, ccie, IP Routing, Router, security, Technology and Software — ciscotips @ 10:16 pm

One of my old student who is preparing for CCNP asked me on how to write an access-list for permitting/denying even or odd networks. So I am just pasting my email reply to him

Here is a simple tip to write an access-list for even or odd networks.

Lets say we are asked to permit all odd or permit all even for 192.168.1.0/24 ?

We’ll play the game with last octet or I should say the least significant bit of last octet.

-If it is 0, the IP address will be Even

-If it is 1, the IP address will be Odd 

192.168.1.00000001 = 192.168.1.1 – odd

192.168.1.00000011 = 192.168.1.3  – odd

192.168.1.00000010 = 192.168.1.2   even

192.168.1.00000100 = 192.168.1.4   even

FOR Even Networks

The IP address will be 192.168.1.0

With the wild card mask as 0.0.0.254

254 = 11111110

Here, 0 means DO CARE of the last bit in IP address (must be ZERO)

Hence ACL will be

access-list 1 permit 192.168.1.0  0.0.0.254

For Odd Networks

The IP address will be 192.168.1.1

With the wild card mask as 0.0.0.254

254 = 11111110

Here, 0 means DO CARE of the last bit in IP address (must be ONE)

Hence ACL will be

access-list 1 permit 192.168.1.1 0.0.0.254
 

  

October 15, 2008

Narbik’s Bootcamp Day-2

Filed under: Router — ciscotips @ 4:40 pm

The day started with excellent humor from Narbik 🙂 and then he grilled all of us with OSPF. I must say Now I know why I scored so less in my IGP. Here is what he covered in his OSPF and EIGRP class.

-RID,Areas
-LSA’s
-Adjacency
-N/w Types
-Fast neighbor down detection
-DB overload protection
-Authentication
-Filtering
-Summary
-Area Types

Guys trust me, It just opened my eyes wide. It was not just overview. I simply loved it!

Here are the EIGRP topics we covered
-Update
-Passive-interface
-Summary
-default route
-Authentication
-Metric
-Stub

Last but not least, excellent workbook and bootcamp labs.

October 14, 2008

Narbik’s Bootcamp Day-1

Filed under: ccie, IP Routing, Router — ciscotips @ 7:35 pm

This is my first ever training class of Cisco. I never knew what to expect. Most of the guys have either attended boot-camps from other vendors or have attended other cisco classes in the past. For me its all for the first time. Without bragging I must say Narbik class is full of tips and tricks 🙂 . People say no to experiments AND do exactly what is specified in doc cd but Narbik is different. He recommendsless commands to accomplish the task. Simply do what is meaningful. Don’t do things which doesn’t mean anything?

The first day was 60-70% hands on as Narbik handed us 5 volumes of Advance CCIE R&S workbook. and a seperate bootcamp workbook. First day we did basic switching hands on and then Narbik went through Security topics ( Theory/White board… no slides/projectors). Here is the list

Vlan Mapping
MAC Floding
DHCP snooping
IP source-guard
DAI
MAC ACL’s
VLAN ACL’s
Private VLan’s

And some Great Tips on FR, which I’ll probably share in my later posts.

March 5, 2008

Cisco Graphical Simulator or GNS3

Filed under: cisco, Router, Switching, Technology and Software — ciscotips @ 6:38 pm

What is GNS3 ?

GNS3 is a graphical network simulator that allows you to design complex network topologies and to launch simulations on them.

To allow complete simulations, GNS3 is strongly linked with :

  • Dynamips, an IOS emulator which allows users to run IOS binary images from Cisco Systems.
  • Dynagen, a text-based front-end for Dynamips.

GNS3 is a excellent complementary tool to real labs for administrators of Cisco networks or people wanting to pass their CCNA, CCNP, CCIP or CCIE certifications.

It can also be used to experiment features of Cisco IOS or to check configurations that need to be deployed later on real routers. This project is an open source product that may be used on multiple platforms, including Windows, Linux, and MacOS X.

Features overview

  • Designing high quality complex network topologies.
  • Emulating Cisco routers.
  • Simulating simple Ethernet, ATM and Frame Relay switches.
  • Load and save in Dynagen’s INI-like format.
  • Image export (JPEG, PNG, BMP and XPM).

Important notice: users must provide their own Cisco IOS to use GNS3.

October 24, 2007

E1/E2 routes in OSPF

Filed under: IP Routing, ospf, Router — ciscotips @ 7:41 am

In OSPF we have 2 types of external routes. E1 and E2

For example 

R1#show ip route
Codes: C – connected, S – static, I – IGRP, R – RIP, M – mobile, B – BGP
D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP

Route redistribution is the process of taking routes learned via one routing protocol and injecting those routes into another routing domain. (Static and connected routes can also be redistributed.) When a router running OSPF takes routes learned by another routing protocol and makes them available to the other OSPF-enabled routers it’s communicating with, that router becomes an Autonomous System Border Router (ASBR). Let’s say R1 is running both OSPF and RIP. R4 is in the same OSPF domain as R1, and we want R4 to learn the routes that R1 is learning via RIP. This means we have to perform route redistribution on the ASBR. The routes that are being redistributed from RIP into OSPF will appear as E2 routes on R4:R4#show ip route ospfO E2 5.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet06.0.0.0/32 is subnetted, 1 subnets

E2 is the default route type for routes learned via redistribution. The key with E2 routes is that the cost of these routes reflects only the cost of the path from the ASBR to the final destination.  It will not reflect the correct “Cost” or path. 

Now if  we want the cost of the routes to reflect the entire path, not just the path between the ASBR and the destination network. The routes must be redistributed into OSPF as E1 routes on the ASBR, as shown here.

.
R1(config)#router ospf 1
R1(config-router)#redistribute rip subnets metric-type 1
Now on R4, the routes appear as E1 routes and have a larger metric, since the entire path cost is now reflected in the routing table.O E1 5.1.1.1 [110/94] via 172.34.34.3, 00:33:21, Ethernet06.0.0.0/32 is subnetted, 1 subnets

July 15, 2007

Enabling Full help in User EXEC level

Filed under: Router — ciscotips @ 9:35 pm

Normally with Router>Show ? , you will not see all available show commands at user level but there is a way to see Full help of Show commands at user level. You would need to enable following command

Router> terminal full-help

Enabling full help, you will witness that there are lot more commands available at User EXEC level.

The system administrator can also configure the system to always display full help for connections made to a particular line using the full-help line configuration command

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