zebra/quagga ospf and unh test section 2

融伯寅

2023-12-01

case 2.1

DR and BDR become adjacent with all other routers.

nsm_twoway_received() changes nbr state from NSM_Init to NSM_ExStart.

two ways can trigger this function.

ospf_hello
|--OSPF_NSM_EVENT_EXECUTE (nbr, NSM_HelloReceived) (NSM_Down-->NSM_NSM_Init)
|--OSPF_NSM_EVENT_EXECUTE (nbr, NSM_TwoWayReceived) (NSM_Init-->NSM_ExStart)

ospf_db_desc
|--OSPF_NSM_EVENT_EXECUTE (nbr, NSM_TwoWayReceived) (NSM_Init-->NSM_ExStart)

case 2.3
ospf_db_desc

case 2.4

ospf_neighbor{}
|--ls_rxmt
|--db_sum
|--ls_req

Negotiation Process refer Page 106 of RFC 2328

Slave router (lower router id) change to NSM_Exchange after received the Initial DD packet from Master.
Master router change to NSM_Exchange after received the ack DD packet from Slave.
OSPF_NSM_EVENT_EXECUTE (nbr, NSM_NegotiationDone) (NSM_ExStart-->NSM_Exchange)

ospf_nsm_event
|--nsm_negotiation_done (add all lsas to database summary list db_sum )

ospf_db_desc
|--ospf_db_desc_proc
|--ospf_ls_request_add (add received lsas to Link State Request list ls_req)

router generates event NSM_ExchangeDone after db_sum is empty.
the slave always generates event NSM_ExchangeDone before the master.
ospf_db_desc_proc
|--OSPF_NSM_EVENT_SCHEDULE (nbr, NSM_ExchangeDone)(NSM_Exchange-->NSM_Loading)
       |--nsm_exchange_done
            |--ospf_ls_req_send

case 2.5
for router lsa
ospf_ls_upd
|--ospf_lsa_more_recent
|--ospf_flood
       |--ospf_lsa_is_self_originated
       |--ospf_process_self_originated_lsa
            |--ospf_router_lsa_timer_add (for router lsa)
            or
            |--ospf_schedule_lsa_flush_area (for network lsa)
            |--ospf_network_lsa_timer_add

for network lsa and router id is changed.
ospf_ls_upd
|--ospf_lsa_flush_area

case 2.6

ospf_ls_upd
|--ospf_ls_upd_send_lsa (nbr, current, OSPF_SEND_PACKET_DIRECT)

case 2.7

ospf_ls_upd

ospf_ls_req

case 2.8
Part A
Slave dont retransmit the non-initial DD packet.
ospf_db_desc
|--OSPF_NSM_EVENT_EXECUTE (NSM_NegotiationDone) (NSM_ExStart-->NSM_Exchange)
       |--nsm_timer_set
          |--if (!IS_SET_DD_MS (nbr->dd_flags)) (the router is slave)
            |--OSPF_NSM_TIMER_OFF (nbr->t_db_desc)


Part B
ospf_db_desc
|--ospf_db_desc_resend

Part C
nbr->t_db_desc is on when nbr change to NSM_ExStart, and is not off when change to NSM_Exchange if the router is master

case 2.9
ospf_db_desc

ospf_db_desc_proc

case 2.10
ospf_ls_upd
|--ospf_flood
       |--ospf_flood_through
            |--ospf_flood_through_area (lsa->area, inbr, lsa)
                 |--ospf_flood_through_interface
                      |--ospf_ls_upd_send_lsa (oi->nbr_self, lsa, OSPF_SEND_PACKET_INDIRECT)


       |--ospf_lsa_install
       |--if (lsa_ack_flag)
       |--ospf_flood_delayed_lsa_ack (nbr, new)


[note]parameter "inbr" will be used to distinguish the called context whether the given LSA was received from the neighbor, or the flooding for the LSA starts from this node (e.g. the LSA was self-originated, or the LSA is going to be flushed from routing domain)

[note]
BDR maybe receive new lsa from DR in the following conditions:
1.the new lsa is originated by DR
2.the new lsa is originated by DR Other and flooded by DR

ospf_ls_upd
|--ospf_flood
       |--ospf_flood_through
            |--ospf_flood_through_area (lsa->area, inbr, lsa)
                 |--ospf_flood_through_interface

lsa_ack_flag will be true in the following conditions:
1. inbr is DR or BDR
2. the router is BDR.(but in ospf_flood_delayed_lsa_ack() only lsa from DR is acked.)


|--ospf_ls_upd_send_lsa (oi->nbr_self, lsa, OSPF_SEND_PACKET_INDIRECT)
     |--ospf_ls_upd_send
          |--if (oi->state == ISM_DR || oi->state == ISM_Backup)
          |--p.prefix.s_addr = htonl (OSPF_ALLSPFROUTERS)

          |--p.prefix.s_addr = htonl (OSPF_ALLDROUTERS)


ospf_flood
|--ospf_flood_delayed_lsa_ack (nbr, new)

implied ack is in
ospf_ls_upd
|--ospf_lsa_more_recent() == 0

Part C (BDR will flood it?)
nsm_timer_set
|--OSPF_NSM_TIMER_ON (ospf_ls_upd_timer)

ospf_flood_through_interface
|--ospf_ls_retransmit_add

case 2.13
ospf_router_lsa_refresh
|--ospf_flood_through_area
       |--ospf_flood_through_interface (lsa->area, inbr, lsa) (inbr is NULL)
            |--ospf_ls_retransmit_add

if RUT and the nbr router are both DR Other, they won't form adjacency and the nbr state is NSM_TwoWay, which is less than NSM_Exchange.
so the new router lsa is not added into ls retransmit list

case 2.14

case 2.16
see case 2.13 and 2.14

case 2.18
Part A
ospf_ls_req

Part B
higher sequence number is added to ls req list in dd exchange process.
ospf_db_desc
|--ospf_db_desc_proc
       |--ospf_ls_request_add
            |--ospf_lsdb_add (new_lsa->lock = 2)
       |--ospf_lsa_discard (new_lsa->lock = 1)

zebra/quagga ospf and unh test section 2

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