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Back to basics : Networking - Part 2

IPV6 Basics:

  • IPV6 uses 32 bit address space whereas IPV6 uses 128 bit address space
  • Represented by eight groups of hexadecimal quadrants and uses Classless Interdomain Routing(CIDR)
  • First 48 bits of the address are the network prefix, next 16 characters are subnet ID and last 64 characters are interface identifiers
  • There are three kinds of IPV6 addresses  are Unicast,Multicast and Anycast
  • Unicast: Identifies a single interface, equalent to IPV4 address of a machine
  • Multicast: Identifier for Multiple network interfaces. Commonly used for sending signals to a given group of systems or for braodcasting videos to multiple computers etc
  • Anycast: The pacaket is delivered to the nearest(in terms of routing) device
  • IPV6 does not have broadcast messages
  • Unicast and Anycast addresses have the following scopes:
  • Link-local: Scope is local link(ie nodes on same subnet).Prefix for link-local addresses is FE80::/64
  • Site-Local:Scope is organization ie private site addressing.Prefix is FECO::/48
  • Global: Used for IPV6 internet addresses, which are globally routable
Difference between TCP and UDP:

  • TCP is connection oriented protocol, Data will be delivered even if the connection is lost, because the server will requiest the lost part. Also there will not be any corruption while  transferring a message. Whereas UDP is a connection less protocol, in the sense that you send it and forget it. There is no guarentee of corruption free transmission
  • TCP:If they messages are send one after the other, the message that is sent first will reach first. In case of UDP, you cannot be sure of the order in  which the data arrives
  • TCP: Data is sent as as a stream with nothing distinguising where the packet starts or ends. UDP(dats is sent as datagrams and will be whole when they reach
  • TCP examples: world wide web.SMTP.FTP,SSH
  • UDP examples: DNS,VOIP,TFTP etc
Spanning tree protocol: Ensures that there are no loops while creating redundant paths in your network


One switch is selected as root switch, which take decisions such as which port to put in forwarding mode and which port in blocking mode etc is taken by this switch

Command to set root switch for a vlan: 
set spantree root vlan_id 


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