October 29, 2012 at 10:36Cisco CCNA Quick Notes (Part of ICND1)
- Tutorial
Greetings!
In this post, I structured the notes created with the students in the courses in the process of repeating the material covered. Initially, all this was done in a notebook. There are no detailed descriptions in the post, etc. Added a few charts and designed in order. In general, consider the information as short cheat sheets that you can read in the evening before passing the exam to quickly refresh everything in your memory. If it is interesting, then you can lay out ICND2, and there are many other things in the same vein.
Address classes and first octet rule:
The problem of the lack of IP addresses and its solutions:
1. Private / Public addresses
a. A 10.xxx
b. B 172.16.xx - 172.31.xx
c. C 192.168.xx
2. Subnet Mask / VLSM / CIDR
3. NAT
4. IPv6
The process of forming a TCP connection (3-Way Handshake):
TCP-Window:
Boot process:
Configuration Methods:
1. CLI
a. Console
b. AUX (Routers)
c. VTY (Telnet / ssh)
2. GUI
a. Web Server (horror)
b. SDM
3. SNMP
Configuration Modes:
Getting help:
Verification:
Saving the configuration file:
Metric - route selection within the protocol.
Administrative distance (AD) - choice of a route between protocols. From 0 to 255. Less = better.
Protocol Classes:
Example 1:
192.168.2.0/24
11000000.10101000.00000010. 00000000 192.168.2.0 / 24 network
11111111.11111111.11111111. 00000000 255.255.255.0 mask
11000000.10101000.00000010. 00000001 192.168.2.1 1 host
11000000.10101000.00000010. 11111110 192.168.2.254 Last host
11000000.10101000.00000010. 11111111 192.168.2.255 Broadcast
Example 2:
This range is 195.1.1.0 / 24 divided into visits:
Terminology:
Configuring RTR-DHCP:
RTR-RELAY Setup:
PPP:
Configuring Serial Interfaces:
For check:
Protocols at level 3:
Routing Protocols:
Routing Protocol Classes:
VLSM / CIDR Support:
Setup Steps:
Rip:
Rtr-a
RTR-B:
Verification:
Search for iOS during the boot process:
Configuration Register:
View and edit:
If there is no free space for copying a new iOS:
If there is free space:
In this post, I structured the notes created with the students in the courses in the process of repeating the material covered. Initially, all this was done in a notebook. There are no detailed descriptions in the post, etc. Added a few charts and designed in order. In general, consider the information as short cheat sheets that you can read in the evening before passing the exam to quickly refresh everything in your memory. If it is interesting, then you can lay out ICND2, and there are many other things in the same vein.
Network layer: IP
- 32-bit Address Length
- The notation Dotted-Decimal is used for recording. We beat it in octets of 8 bits, write it in decimal, separate it with a dot: 10.1.1.1
Address classes and first octet rule:
| Class | Address range (first octet) | Network / Host Length | First octet rule |
|---|---|---|---|
| A | 1-127 | 8.24 | 0xxxxxxx |
| B | 128-191 | 16.16 | 10xxxxxx |
| C | 192-223 | 24.8 | 110xxxxx |
| D | 224-239 | Multicast | 1110xxxx |
| E | 240-255 | Experimental | 1111xxxx |
The problem of the lack of IP addresses and its solutions:
1. Private / Public addresses
a. A 10.xxx
b. B 172.16.xx - 172.31.xx
c. C 192.168.xx
2. Subnet Mask / VLSM / CIDR
3. NAT
4. IPv6
Transport Layer: UDP / TCP
| Protocol | Specifications | |
|---|---|---|
| TCP | Reliable | Forms a pre-connection (Connection-oriented) |
| UDP | Unreliable (Best-Effort) | Connection does not form (Connectionless) |
The process of forming a TCP connection (3-Way Handshake):
TCP-Window:
- Ability to send N-data segments and get a single ACK.
- Fixed (window size is fixed) & Scaling (exchange changes during the session) Window.
Work with Cisco IOS
Boot process:
- BIOS> POST
- BIOS> Bootstrap
- Bootstrap> iOS
- IOS> Startup-config
Configuration Methods:
1. CLI
a. Console
b. AUX (Routers)
c. VTY (Telnet / ssh)
2. GUI
a. Web Server (horror)
b. SDM
3. SNMP
Configuration Modes:
| Title | Description | Invitation | Deep into | Up |
|---|---|---|---|---|
| USER EXEC | User mode. Almost no rights. | > | enable | exit logout |
| PRI EXEC | Privileged mode. Administrator rights. Logging, debug. Transition to configuration modes. | # | configure terminal | Exit Logout Disable |
| GLOBAL CONFIG | Global configuration mode. Parameters that affect the device as a whole are configured. | (config) # | Interface ... Vlan ... Router ... Controller ... | Exit CTRL-Z (immediately in PRI EXEC) |
| SUB CONFIG | We configure interfaces, vlana, routing protocols, etc. | (config-if) # (config-line) # And etc. | Exit CTRL-Z (immediately in PRI EXEC) |
Getting help:
- ? - all mode commands
- ab? - teams starting with ab
- command? - arguments to command
Basic Switch Configuration
! ! Set the device name and domain name. FQDN is required to configure SSH. ! hostname SW1 ip domain-name CISCO.LOCAL ! ! Create a virtual L3 interface. We throw it in the 1st vlan. Assign IP. ! Turn on. ! For the interface to go up, at least 1 active interface in the specified Vlan is required. ! interface vlan 1 ip address 1.1.1.1 255.0.0.0 no shutdown ! ! Default Gateway in global mode. To administer the switch from other ! networks. ! ip default-gateway 1.1.1.254 !
Basic Security
! ! Connection Protection (USER EXEC). ! ! Console Port Security ! line console 0 login - enable password authentication password PASSWORD - password for authentication ! ! Network connection protection. Virtual Terminals (vty). ! We configure and enable only the SSH protocol. ! ! User Creation ! username ROOT secret CISCO username ADMIN secret OCSIC ! ! Enabling SSH and key generation ! crypto key genereate rsa ! ! Configuring vty ports ! line vty 0 15 login local - authentication based on user and password database transport input ssh - allow only SSH connections ! ! Preferred Mode Protection ! enable password OCSIC - the password is stored in clear text enable secret CISCO - password is stored as a hash ! ! Encrypt passwords stored in clear text ! service password-encryption ! ! Banner creation ! banner motd @ -------------------------------------------------- ---- Unauthorized access is blah-blah-blah -------------------------------------------------- - @ ! ! Port Security ! interface fa0 / 1 switchport mode access ! We define safe (legal) addresses: ! - maximum number of legal addresses switchport port-security maximum 10 ! - static indication of a legal address switchport port-security mac-address 0001.0002.0003 ! - dynamic determination of legal addresses and their entry in running-config switchport port-security mac-address sticky switchport port-security violation shutdown - in case of violation, disable the port switchport port-security - enable port-security on the interface
Verification:
show running-config - current configuration file show startup-config - boot configuration file show int - interface information show int vlan 1 show int fa0 / 1 show ip int brie show port-security - port security check show port-security int fa0 / 1 show port-security address show version - device information
Saving the configuration file:
copy running-config startup-config
Routing
Metric - route selection within the protocol.
Administrative distance (AD) - choice of a route between protocols. From 0 to 255. Less = better.
| Protocol | Metrics | AD |
| Connected | - | 0 |
| Static | - | 1 |
| EIGRP | Metric = 256 * (BW + Delay) | 90 |
| OSPF | Cost = 100 / BW Mbps | 110 |
| Rip | Hop count | 120 |
Protocol Classes:
- Distance Vector (RIP, IGRP, EIGRP)
- Link-State (OSPF, IS-IS)
Masking
Example 1:
192.168.2.0/24
11000000.10101000.00000010. 00000000 192.168.2.0 / 24 network
11111111.11111111.11111111. 00000000 255.255.255.0 mask
11000000.10101000.00000010. 00000001 192.168.2.1 1 host
11000000.10101000.00000010. 11111110 192.168.2.254 Last host
11000000.10101000.00000010. 11111111 192.168.2.255 Broadcast
Example 2:
This range is 195.1.1.0 / 24 divided into visits:
- 2 networks of 30 hosts
- 4 networks of 6 hosts
- 2 transport networks
1.30 hosts 2 ^ n-2> = 30 n = 5
---------
11000011.00000001.00000001.000 00000 195.1.1.0 / 27 Subnet Zero
11111111.11111111.11111111.111 00000 255.255.255.224
11000011.00000001.00000001.000 00001 195.1.1.1 / 27 1 host
11000011.00000001.00000001.000 11110 195.1.1.30 / 27 last host
11000011.00000001.00000001.000 11111 195.1.1.31 / 27 broadcast
11000011.00000001.00000001.001 00000 195.1.1.32 / 27 Second network
11000011.00000001.00000001.001 00001 195.1.1.33 / 27
11000011.00000001.00000001.001 11110 195.1.1.62 / 27
11000011.00000001.00000001.001 11111 195.1.1.63 / 27
11000011.00000001.00000001.010 00000 195.1.1.64 / 27 Third ...
11000011.00000001.00000001.010 00001 195.1.1.65 / 27
11000011.00000001.00000001.010 11110 195.1.1.94 / 27
11000011.00000001.00000001.010 11111 195.1.1.95 / 27
11000011.00000001.00000001.011 00000 195.1.1.96 / 27
11000011.00000001.00000001.011 00001 195.1.1.97 / 27
11000011.00000001.00000001.011 11110 195.1.1.126 / 27
11000011.00000001.00000001.011 11111 195.1.1.127 / 27
...
11000011.00000001.00000001.111 00000 195.1.1.224 / 27
11000011.00000001.00000001.111 00001 195.1.1.225 / 27
11000011.00000001.00000001.111 11110 195.1.1.254 / 27
11000011.00000001.00000001.111 11111 195.1.1.255 / 27
2.6 hosts 2 ^ n-2> = 6 n = 3
11000011.00000001.00000001.010 00 000 195.1.1.64 / 29
11111111.11111111.11111111.111 11 000 255.255.255.248
11000011.00000001.00000001.010 00 001 195.1.1.65 / 29
11000011.00000001.00000001.010 00 110 195.1.1.70 / 29
11000011.00000001.00000001.010 00 111 195.1.1.71 / 29
11000011.00000001.00000001.010 01 000 195.1.1.72 / 29
11000011.00000001.00000001.010 01 001 195.1.1.73 / 29
11000011.00000001.00000001.010 01 110 195.1.1.78 / 29
11000011.00000001.00000001.010 01 111 195.1.1.79 / 29
11000011.00000001.00000001.010 10 000 195.1.1.80 / 29
11000011.00000001.00000001.010 10 001 195.1.1.81 / 29
11000011.00000001.00000001.010 10 110 195.1.1.86 / 29
11000011.00000001.00000001.010 10 111 195.1.1.87 / 29
11000011.00000001.00000001.010 11 000 195.1.1.88 / 29
11000011.00000001.00000001.010 11 001 195.1.1.89 / 29
11000011.00000001.00000001.010 11 110 195.1.1.94 / 29
11000011.00000001.00000001.010 11 111 195.1.1.95 / 29
3.2 hosts n = 2
11000011.00000001.00000001.010 10 0 00 195.1.1.80 / 30
11111111.11111111.11111111.111 11 1 00 255.255.255.252
11000011.00000001.00000001.010 10 0 01 195.1.1.81 / 30
11000011.00000001.00000001.010 10 0 10 195.1.1.82 / 30
11000011.00000001.00000001.010 10 0 01 195.1.1.83 / 30
11000011.00000001.00000001.010 10 1 00 195.1.1.84 / 30
11000011.00000001.00000001.010 10 1 01 195.1.1.85 / 30
11000011.00000001.00000001.010 10 1 10 195.1.1.86 / 30
11000011.00000001.00000001.010 10 1 11 195.1.1.87 / 30
Terminology:
195.1.1.0 / 24 Network (Mask = Class) 195.1.0.0 / 16 Summary (Mask <Class) 195.1.1.0 / 30 Subnet (Mask> Class) 195.1.1.1 / 32 Host (Mask = 32) 0.0.0.0 / 0 Default Route
Using a router as a DHCP server
Configuring RTR-DHCP:
! Exclusive range (router addresses) ! ip dhcp excluded-address 1.1.1.1 ip dhcp excluded-address 2.1.1.2 2.1.1.20 ! ! Creating an address pool for the network 1.1.1.0 (connected) ! ip dhcp pool NET1 network 1.1.1.0 255.255.255.0 - address pool default-router 1.1.1.1 - default gateway dns-server 1.1.1.1 8.8.8.8 - DNS server ! ! ! Creating an address pool for the 2.2.2.0 network (remote, via relay) ! ip dhcp pool NET2 network 2.2.2.0 255.255.255.0 - address pool default-router 2.2.2.1 - default gateway dns-server 1.1.1.1 8.8.8.8. - DNS server Verification: Sh ip dhcp bindings Sh ip dhcp conflicts Sh ip dhcp s
RTR-RELAY Setup:
! Forward broadcast packets to the specified address int fa0 / 1 ip address 2.2.2.1 255.255.255.0 - interface on the remote network 2.2.2.0 ip helper-address 1.1.1.1 - where to forward (DHCP address) ! ! Forward only UDP67 Broadcasts Ip forward-protocol udp 67
Remote Access (telnet / ssh)
| Customer teams | Description |
| 1.1.1.1 HOSTNAME telnet 1.1.1.1 ssh -l USERNAME 1.1.1.1 | Open connection |
| CTRL + SHIFT + 6 - X | return to local session |
| show sessions | view connections |
| ENTER-ENTER | return to the last active session (*) |
| 2 Resume 2 | return to connection # 2 |
| disconnect 2 | close connection # 2 |
| Server Commands | Description |
| Show users | who is connected |
| Send | Chat |
| Clear line vty 1 | disable vty 1 |
| Show ssh | view ssh connections |
Wan
PPP:
1. LCP = Link Control Protocol
a. Compession
b. Error detection
c. Authentication
2. NCP = Network Control Protocol
a. IPCP
b. IPV6CP
c. CDPCP
Configuring Serial Interfaces:
show controllers - defined by DCE or DTE ! interface serial 1/0 clock rate 64000 - speed in bps (on the DCE interface) bandwidth 64 - used to calculate the metric (kbps) encapsulation ppp - set encapsulation ip address 4.4.4.1 255.255.255.252 no shutdown !
For check:
Sh interface s1 / 0 Sh controllers s1 / 0
RIP Protocol
Protocols at level 3:
- Routing (RIP, OSPF, EIGRP)
- Routed (IP, IPv6, IPX, AppleTalk)
Routing Protocols:
- IGP - Inside AS (RIP, OSPF, EIGRP)
- EGP - Between AS (BGP)
Routing Protocol Classes:
- Distance-Vector: RIP, IGRP
- Advanced Distance-Vector: EIGRP, BGP
- Link-State: OSPF, IS-IS
VLSM / CIDR Support:
- Classfull (RIPv1, IGRP)
- Classless (RIPv2, BGP, OSPF, EIGRP, IS-IS)
Setup Steps:
- 1. Enable routing protocol
- 2. Select local interfaces. Choosing an interface means that:
- a. Interface sends updates
- b. Interface receives updates
- c. Interface network will be included in updates
Rip:
| Rip1 | Rip2 |
| Class | Classless |
| UDP520 | UDP520 |
| Updates sends to 255.255.255.255 | Updates sends to 224.0.0.9 |
| Supports authentication | |
| Supports Manual Summation |
Rtr-a
sh ip interface brief - looked at interfaces ! router rip - enable RIP version 2 - enable RIPv2 network 1.0.0.0 - select local interfaces. In RIP, Class Networks network 2.0.0.0 no auto-summary - disable auto-summarization (the router will transmit ! subnets, instead of class network addresses)
RTR-B:
router rip version 2 network 2.0.0.0 no auto-summary
Verification:
show ip protocols show ip route rip show ip rip? debug ip rip
Control
Search for iOS during the boot process:
- NVRAM: config-register
- NVRAM: startup-config (boot system commands)
- First iOS file from Flash:
- If not found, then 3 times tries to find iOS on tftp (Broadcast)
- ROMMON
Configuration Register:
• 16 bit
• Each bit somehow affects the boot process
• For the IOS search, bits c 0 through 3 are responsible:
o 0x0 ROMMON
o 0x1 Boot IOS from ROM
o 0x2-F Standard boot
View and edit:
Show version Config-register 0x2100 - boot to ROMMON (last 0) Ios update sh flash - make sure you have free space dir flash
If there is no free space for copying a new iOS:
#copy flash: ios.old tftp: //1.1.1.1 - Backup old IOS (just in case) ! Free up space: ! Formatting flash (if not sorry) #erase flash: ! Or delete individual files #del flash: ios.old ! #copy tftp: //1.1.1.1/newios flash: - Copy the new iOS ! #reload - Reboot
If there is free space:
#copy tftp: //1.1.1.1/newios flash: - Copy the new iOS (config) #boot system flash: newios - instruct to boot into the new iOS #copy running startup - Save the config #reload - Reboot
IOS Recovery:
ROMMON> tftpdnld
Password Recovery:
- Reboot (turn off)
- Click CTRL-Break
- We get into ROMMON
! In ROMMOM, we change the 6th bit (2142) in the configuration register. The value of the bit is ! ignore boot config ROMMON> confreg 0x2142 ! We are overloaded ROMMON> reset ! Startup-config will be ignored at boot. We restore it. #copy startup runn ! We return the configuration register (config) # config-register 0x2102 ! Change password (config) #enable secret cisco ! Save the config #copy runn start
Additional monitoring and management teams
show tech-support | redirect tftp: //1.1.1.1/filename - show all show processes - CPU and RAM usage show processes cpu history