CCNA-1. Chapter6. Aderssing the IPv4 network.

Types of IPv4 network addresses:

• Network address - The address by which we refer to the network
• Broadcast address - A special address used to send data to all hosts in the network
• Host addresses - The addresses assigned to the end devices in the network

In an IPv4 network, the hosts can communicate one of three different ways:

• Unicast - the process of sending a packet from one host to an individual host
• Broadcast - the process of sending a packet from one host to all hosts in the network
  
  • Types:
    
    • Directed broadcast (to all hosts on a non-local network. by default Routers do not forward)
    • Limited broadcast.(to the hosts on the local network. Routers do not forward)
• Multicast - the process of sending a packet from one host to a selected group of hosts

IPv4 network specific address types:

• Limited broadcast.(255.255.255.255.) to the hosts on the local network
• Experimental Addresses (240.0.0.0-255.255.255.254) reserved for future use (RFC 3330). Cannot be used.
• Multicast adresses (224.0.0.0 - 239.255.255.255)
  
  • Multicast reserved link local addresses (224.0.0.0-224.0.0.255) . Multicast groups on a local network. (TTL)=1         224.0.0.10 - EIGRP
• Multicast globally scoped addresses (224.0.1.0-238.255.255.255) Multicast across the Internet.                                     224.0.1.1 - NTP

• Private Addresses (10.0.0.0-10.255.255.255;172.16.0.0-172.31.255.255;192.168.0.0-192.168.255.255) Not routed in Internet
• Default Route ( 0.0.0.0) a "catch all" route. The use of this address also reserves 0.0.0.0-0.255.255.255)
• Loopback (127.0.0.1) directs traffic to localhost. The use of this address also reserves 127.0.0.0-127.255.255.255)
• Link-local addresses (169.254.0.0-169.254.255.255) automatically assigned if no IP configuration is available.
• TEST-NET Addresses (192.0.2.0-192.0.2.255) for teaching and learning purposes. Can be used. Not routed in Internet.

Global IP address redistributors:

• Internet Assigned Numbers Authority (IANA) (http://www.iana.net) manages multicast addresses and the IPv6 addresses
• IPv4 address space allocate Regional Internet Registries (RIRs):
  
  • AfriNIC (African Network Information Centre) - Africa Region http://www.afrinic.net
  • APNIC (Asia Pacific Network Information Centre) - Asia/Pacific Region http://www.apnic.net
  • ARIN (American Registry for Internet Numbers) - North America Region http://www.arin.net
  • LACNIC (Regional Latin-American and Caribbean IP Address Registry) - Latin America and some Caribbean Islands http://www.lacnic.net
  • RIPE NCC (Reseaux IP Europeans) - Europe, the Middle East, and Central Asia http://www.ripe.net

IPv6 features:

• Improved packet handling
• Increased scalability and longevity
• QoS mechanisms
• Integrated security

IPv6 offers:

• 128-bit hierarchical addressing - to expand addressing capabilities
• Header format simplification - to improve packet handling
• Improved support for extensions and options - for increased scalability/longevity and improved packet handling
• Flow labeling capability - as QoS mechanisms
• Authentication and privacy capabilities - to integrate security

Formula for calculating subnets: 2^n where n = the number of bits borrowed



Formula for calculating the number of hosts: 2^n - 2 where n = the number of bits left for hosts.



ICMP messages that may be sent include:

• Host confirmation (ICMP Echo Request - ICMP Echo Reply)
• Unreachable Destination or Service
  
  • Unreachable codes are:
  0 = net unreachable (no route in routing table)
  1 = host unreachable (route exist but host unreachable)
  2 = protocol unreachable (host recieved packet but upper protocol is not avaliable)
  3 = port unreachable (host recieved packet but service daemon is not avaliable)
  
  

• Time exceeded  (ICMP Time Exceeded) TTL field of the packet has expired
• Route redirection (ICMP Redirect) If the next hop is attached to the same interface as client - notify to use another gateway
• Source quench (ICMP Source Quench) router reply if it dosnt have enough buffer space to receive incoming packets