zebra/quagga ospf and unh test section 4

Calculation of the routing table
1.Calculating the shortest-path tree for an area,

  -yields the set of intra-area routes

  -examine router-LSAs and network-LSAs

  -consider those links between routers and transit networks at first, then the stub networks.

2.Calculating the inter-area routes.

  -The inter-area routes are calculated by examining summary-LSAs.

  -If the router has active attachments to multiple areas, only backbone summary-LSAs are examined.

  -Routers attached to a single area examine that area’s summary-LSAs.

3.Examining transit areas’ summary-LSAs

  -only performed by area border routers attached to one or more non-backbone transit areas(transit  area is different from transit network).

  -updates backbone intra-area routes found in Step 1 and inter-area routes found in Step 2.

  -never makes unreachable destinations reachable.

4.Calculating AS external routes

ospf

  |--new_table(route_table)--ospf_route  (for network route)

  |--new_rtrs(route_table)--list--ospf_route (for ABR/ASBR route)

case 4.1

ospf_spf_calculate_timer

  |--ospf_ia_routing

       |--ospf_examine_summaries

            |--process_summary_lsa

                 |--ospf_ia_network_route

                      |--ospf_route_cmp

                 |--ospf_ia_router_route

                      |--ospf_route_cmp

case 4.2

ospf_spf_calculate_timer

  |--ospf_ia_routing

       |--ospf_examine_summaries

            |--process_transit_summary_lsa

                 |--ospf_update_network_route

                     

                 |--ospf_update_router_route

                

                

case 4.3

ospf_ase_calculate_timer     

  |--ospf_ase_calculate_route         

       |--ospf_find_asbr_route (forwarding address is not set)

      

       |--route_node_match(ospf->new_table) (forwarding address is set)

      

case 4.4      

ospf_ase_calculate_timer     

  |--ospf_ase_calculate_route         

       |--ospf_find_asbr_route

                     

case 4.5

ospf_ase_calculate_timer     

  |--ospf_ase_calculate_route         

       |--route_node_lookup (ospf->new_table)

      

      

case 4.6       

ospf_ase_calculate_timer     

  |--ospf_ase_calculate_route         

       |--ospf_route_cmp (line: 472)

      

case 4.7

ospf_route

  |--cost

  |--u.ext.type2_cost

for type 1 ase, cost is asbr_route->cost + metric

for type 2 ase, cost is asbr_route->cost

ospf_ase_calculate_timer     

  |--ospf_ase_calculate_route  

       |--ospf_ase_calculate_new_route  

       |--ospf_route_cmp      

case 4.8

ospf_ase_calculate_timer     

  |--ospf_ase_calculate_route  

       |--ospf_route_cmp

            |--ospf_asbr_route_cmp

           

           

case 4.9

case 4.10

ospf_ase_calculate_timer     

  |--ospf_ase_calculate_route  

       |--ospf_route_cmp

            |--ospf_asbr_route_cmp

                 

these two cases check for intra-area backbone paths vs inter-area paths, case 4.7 and 4.8 check for intra-area non-backbone paths vs intra-area backbone paths