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||''Reference -''[http://conferences.sigcomm.org/co-next/2009/workshops/rearch/papers/Feldmann.pdf]||

 == HAIR Hierarchical Architecture for Internet Routing ==
  * Routing table growth 
  * Restrict visibility of Routing updates 
  * Support Traffic Engineering 
  * Mobility and Multipath
  
''' Edge Based Approach '''
 N layer -Hierarchial Structure :

 ||''' *** '''|| ''Group '''core''' networks into level 1 of a hierarchy, '''edge''' or intermediate networks into levels 2 to n − 1, and '''local area networks into level n''', obtaining a '''hierarchy''' consisting of '''n levels'''''
  
 ||'''EDGE'''|| 
 * This would refer to level -n ( directly interact with the end hosts. (bottom layer of hierarchy) [ '' Ethernet LAN''']
 

 ||''' INT'''||
 * This is the intermediate level ( 2 to n-1). 
 * Network of '''routers only'''
 * It provides routing between attached EDGEs or INTs of the next higher level. 

 ||'''CORE'''||
 * Ensures global reachability by routing packets between '''INTs''' (level-2) 

 ||'''''Attachment Points'''''||
 * Levels are connected via ''attachment points'': a level -k (LkAP) connects level-k routing '''domain''' to level k+1 domain
 * Allows '''peering'''


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 ||''' Routing Tables '''||

||Within a INT||
 * Need entries for all routers within the INT, 
 * Routes to the attached EDGEs/INTs, 
 * Default routes to the INTs of the next ''higher level'' or the ''CORE''

|| Within a CORE||
 * All routers within CORE
 * Routes to directly connected ISPs
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||''' LOCATION/IDENTIFIER SEPARATION'''||

  * Separation of location and identity 
  * Locators are variable length (variable path from ''core'' towards ''end host'')
  

  || ''' Note''' | ''Use '''GUID'''  for location and identity separation  ''||


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||''' PACKET DELIVERY'''||  
 
 A packet sent from Host A to Host B 
 * Forward '''to CORE'''
 * Forward '''within CORE'''
 * Forward from '''CORE''' down '''to''' the ''' destination host''' 


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 ||'''Question'''||
 * Is cluster or level based approach is what mobility first requires 
 * How feasible similar approach could be to attain standard routing across varied use cases