Tag Archives: IOS

Cisco Order of Operations

Existem 2 tabelas importantes que indicam a ordem das operações no IOS são a do NAT e QoS.

Operações no NAT:

Inside-to-Outside Outside-to-Inside
  • If IPSec then check input access list
  • decryption – for CET (Cisco Encryption Technology) or IPSec
  • check input access list
  • check input rate limits
  • input accounting
  • redirect to web cache
  • policy routing
  • routing
  • NAT inside to outside (local to global translation)
  • crypto (check map and mark for encryption)
  • check output access list
  • inspect (Context-based Access Control (CBAC))
  • TCP intercept
  • encryption
  • Queueing
  • If IPSec then check input access list
  • decryption – for CET or IPSec
  • check input access list
  • check input rate limits
  • input accounting
  • redirect to web cache
  • NAT outside to inside (global to local translation)
  • policy routing
  • routing
  • crypto (check map and mark for encryption)
  • check output access list
  • inspect CBAC
  • TCP intercept
  • encryption
  • Queueing

Operações no QoS:

Inbound Outbound
  1. QoS Policy Propagation through Border Gateway Protocol (BGP) (QPPB)
  2. Input common classification
  3. Input ACLs
  4. Input marking (class-based marking or Committed Access Rate (CAR))
  5. Input policing (through a class-based policer or CAR)
  6. IP Security (IPSec)
  7. Cisco Express Forwarding (CEF) or Fast Switching
  1. CEF or Fast Switching
  2. Output common classification
  3. Output ACLs
  4. Output marking
  5. Output policing (through a class-based policer or CAR)
  6. Queueing (Class-Based Weighted Fair Queueing (CBWFQ) and Low Latency Queueing (LLQ)), and Weighted Random Early Detection (WRED)

Cisco CLI Shortcuts

Capability
Purpose

Move around the command line to make changes or corrections.

Ctrl-B or the left arrow key

Move the cursor back one character.

Ctrl-F or the right arrow key

Move the cursor forward one character.

Ctrl-A

Move the cursor to the beginning of the command line.

Ctrl-E

Move the cursor to the end of the command line.

Esc B

Move the cursor back one word.

Esc F

Move the cursor forward one word.

Ctrl-T

Transpose the character to the left of the cursor with the character located at the cursor.

Recall commands from the buffer and paste them in the command line. The wireless device provides a buffer with the last ten items that you deleted.

Ctrl-Y

Recall the most recent entry in the buffer.

Esc Y

Recall the next buffer entry.

The buffer contains only the last 10 items that you have deleted or cut. If you press Esc Y more than ten times, you cycle to the first buffer entry.

Delete entries if you make a mistake or change your mind.

Delete or Backspace

Erase the character to the left of the cursor.

Ctrl-D

Delete the character at the cursor.

Ctrl-K

Delete all characters from the cursor to the end of the command line.

Ctrl-U or Ctrl-X

Delete all characters from the cursor to the beginning of the command line.

Ctrl-W

Delete the word to the left of the cursor.

Esc D

Delete from the cursor to the end of the word.

Capitalize or lowercase words or capitalize a set of letters.

Esc C

Capitalize at the cursor.

Esc L

Change the word at the cursor to lowercase.

Esc U

Capitalize letters from the cursor to the end of the word.

Designate a particular keystroke as an executable command, perhaps as a shortcut.

Ctrl-V or Esc Q

Scroll down a line or screen on displays that are longer than the terminal screen can display.

Note The More prompt appears for output that has more lines than can be displayed on the terminal screen, including show command output. You can use the Return and Space bar keystrokes whenever you see the More prompt.

Return

Scroll down one line.

Space

Scroll down one screen.

Redisplay the current command line if the wireless device suddenly sends a message to your screen.

Ctrl-L or Ctrl-R

Redisplay the current command line.

Diagnosticar a cablagem através do IOS

Por vezes existe a necessidade de durante o troubleshooting efetuar testes á cablagem, trocando o cabo por exemplo. Agora antes de trocar o cabo é possível confirmar se existe algum defeito através do IOS.

Segue o exemplo de um teste a 2 interfaces com estados distinto, o 1º apresenta-se como Up/Up sendo que o 2º como Down/Down. Pretende-se essencialmente identificar as diferenças entre os resultados.

Confirmar o estado das interfaces antes de efetuar o teste

Switch-A#sh int desc
Interface                      Status         Protocol Description
Vl1                            admin down     down
Gi0/1                          up             up       Server1
Gi0/2                          down           down     Server2

Efetuar o teste a uma interface com o estado Up/Up

Switch-A#test cable-diagnostics tdr interface Gi0/1
TDR test started on interface Gi0/1
A TDR test can take a few seconds to run on an interface
Use 'show cable-diagnostics tdr' to read the TDR results.

Após alguns segundos é possível verificar o resultado do teste

Switch-A#show cable-diagnostics tdr interface g0/1
TDR test last run on: September 22 14:57:38

Interface Speed Local pair Pair length        Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi0/1     1000M Pair A     4    +/- 10 meters Pair B      Normal
                Pair B     4    +/- 10 meters Pair A      Normal
                Pair C     4    +/- 10 meters Pair D      Normal
                Pair D     4    +/- 10 meters Pair C      Normal

Efetuar o teste a uma interface com o estado Down/Down

Switch-A#test cable-diagnostics tdr interface Gi0/2
TDR test started on interface Gi0/2
A TDR test can take a few seconds to run on an interface
Use 'show cable-diagnostics tdr' to read the TDR results.
Switch-A#show cable-diagnostics tdr interface g0/2
TDR test last run on: September 22 14:58:05

Após alguns segundos é possível verificar o resultado do teste

Interface Speed Local pair Pair length        Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi0/2     auto  Pair A     0    +/- 10 meters N/A         Open
                Pair B     1    +/- 10 meters N/A         Open
                Pair C     0    +/- 10 meters N/A         Open
                Pair D     0    +/- 10 meters N/A         Open
Switch-A#