OSPF,
Reference: https://blog.csdn.net/qq_33789722/article/details/80610827
https://wenku.baidu.com/view/efb32a1ab7360b4c2e3f6449.html
the ISIS - CLNP (strong expansion) - Integrated isis: for MAN
OPEN SHORTEST PATH FIRST Open Shortest Path First
Ospfv2 / 3 - ipv4 / 6
belonging to the link-state routing protocol (LS), and is the total of the standard
theory, there is no network size limit of
hierarchical design support network, the network can be is divided into two layers: the backbone layer; non-backbone layers, each layer must be non-backbone communication backbone layer, is distinguished by gratitude to "area"
backbone area: routing information for the inter-area propagation of
non-backbone area
of all non- backbone must be directly connected to the backbone, for communication
channel region because of the presence in particular, may be divided into different types:
backbone router: all links of the backbone routers belong to
the non-backbone router: all links are non- routers in the backbone area
area border router (ABR, area border router): must connect the backbone area and non-backbone area
boundary routers) (ASBR): a router with the introduction of external road ability, called ASBR ospf the
working principle
1, establish neighbor
a) only use hello packets, ospf routing, just ospf
2 Database Synchronization
a) LSA-link state advertisement, the link state advertisement
3, a routing table is calculated (for spf lsa calculated by the algorithm to obtain the final routing entry)
Establishing an adjacency broadcast network: constituting n (n-1) / 2 neighbor relationships
routing roles: DR (designated router); BDR (backup designated router); other routers
other and only the DR and BDR adjacencies
role election according to ID route 
the route ID: uniquely identifies the region ospf router
router id selection rules
- Command to specify the router ID
- If no manual configuration, the priority select router loopback interface highest IP address; if no loopback interface, then selecting the physical ports highest IP address
metric Ospf of (cost)
Cost = 10 ^. 8 / BW: Shortest Path the interface is based on the specified cost (cost) calculated
Ospf packets:
the Hello: establish the neighbor relationship (multicast)
DBD: dstabase the Description Database Description packets (unicast)
Lsu: Link State Update Link-State Update packet (unicast)
Lsr: Link State Request Link State requests packet (unicast)
LSAck: link state link state acknowledgment packets ACK (unicast) 
Tips: router virtual port
the loopback: loopback port: virtual port, steady state, configured to: test port; management ip (X) of the switch ; OSPF as the ID route
the Null0: null None (hop specified for this data, it is clear data packet)
Ospf邻居建立影响因素：
1、 确保最小范围内链路是互通的
2、 确保设备端口可以发送报文（network；端口不能设置为被动端口/静默端口不收不发；acl设置只对进来的流量，）
3、 确保设备端口可以接受报文（network；端口不能设置为被动端口/静默端口不收不发；acl设置只对进来的穿越流量）
4、 确保ospf hello包中的关键参数一致（ospf id；aera id一致；route id不同；认证必须成功；子网掩码必须相同【特殊情况下：ospf network-type p2p】；hello/dead时间{端口模式下设置}要一致；特殊标记位必须完全相同；DR优先级不能全为0【特殊情况下】；3层MTU必须完全一致）
Configuration command:
Neighbor (neighbors and friends) / adjancy (adjacent to the husband and wife)
neighbor state changes: down - init - 2way (neighbor relationship) - exstart (exchange start) - exchange - loading - FULL ( establishing adjacency state )
global mode
1, ospf 1 (process-id default process ID. 1)
2, area 0 (region established)
. 3, 192.168.10.0 0.0.0.255 Network (declared between ports can be precisely specified route 192.168.10.1 0.0.0.0)
into the ospf area 0; then the port: g0 / 0 / X, is enabled ospf1;
network three functions:
may send packets ospf1
may ospf1 received packets
may be part of the IP address of the network to change the port, package placed ospf1 , transfer out to neighboring routers
verification:
Display ospf 1 the Brief (see itself ospf information)
Display ospf the peer (see ranking order information)
Display the Brief ospf the peer (neighbor simple information)
reset ospf process: after the reset ospf 1 process parameters change 
options (option) it is a special mark in this position, reflecting the ability of a router, scalable open