Notes on the fifth day

Matching conditions

Specify router --- DR --- and MA Establish adjacency relationship with all other devices in the network      Back up the specified router --- BDR --- and MA All other devices in the network establish adjacency relationships in DR and BDR In the presence of both , One MA You need at least four devices in the network to see the neighbor relationship .

DR and BDR Although it is called designated router ( Back up the specified router ), But its scope of work is One MA In the network , therefore , Its essence is the concept of interface .

Matching conditions --- stay MA In the network , If all equipment is adjacent , There will be a large number of repeated updates , therefore , Need to carry out DR/BDR The election of , All non DR/BDR  (DROther) Only maintain the neighbor relationship between them .

DR/BDR The election of --- 1, Compare interface priorities , The highest priority is DR, Second largest For the BDR.

The initial default value of priority is 1.

[r1-GigabitEthernet0/0/0]ospfdr-priority?

1NTEGER<0-2559

Routerpriorityvalue  ---- If you change the priority of an interface to 0, Then it means that the interface puts Discard DR/BDR The election of .

2, When priorities are the same , Then compare R1D     R1D Big router

The corresponding interface is DR, The next largest is BDR.

DR/BDR The election of --- Non preemptive election --- The time of election is equal to the time of death

<r19reset ospf1process  --- restart OsPF process

ospF Data packets of

ospF The agreement number of --- 89

ospf Message header

edition ---- OsPF Version of protocol ---- OsPFv2 The version field is 2.

type ---- OsPF The type of packet

Hello --- 1

DBD --- 2

LsR --- 3

LsU --- 4

LsACK --- 5

packet length --- Whole OsPF Length of data message , Unit byte .

R1D --- Indicates the router that sent this packet R1D

Area 1D --- Of the area where the interface that sent the packet is located 1D

Certification type and certification data   --- OsPF At the time of certification , You need to compare the authentication class first

type , Only when the authentication type is the same can the authentication data be compared .

Authentication type --- null --- Null authentication --- 0

--- simple --- Plaintext Authentication --- 1

--- MD5 --- Compare summary value authentication --- 2

hello package --- Cycle discovery , Establish and maintain neighborhood relations .  --- DR/BDR Election also

It uses hello package

Subnet mask --- issue hello Package interface ip Mask information corresponding to the address ---- Huawei equipment   The subnet mask must be the same for both sides of setting up neighbors , Otherwise, you will not be able to establish a neighborhood system ( Yes P2P The network does not work )

hello Time and time of death --- Both neighbors hello The time and time of death must be the same , no It will lead to the failure of establishing neighborhood relationship .

optional --- 8 position ,8 Tag bits , Each marking position 1, It means that it conforms to OsPF A certain characteristic of .

There is ospf Mark bit of special area , If the neighbors sign a special area A different , You will not be able to establish a normal neighbor relationship .

The priority of the router --- The interface that sent the packet has DR/BDR Priority in elections level .

Specify the router and backup the specified route --- I'm carrying DR/BDR Interface 1P Address .  ---- stay DR/BDR Before it is selected , Use 0.0.0.0 To fill in .

neighbor --- Local known neighbors R1D.

hello Parameters in the package that restrict the establishment of neighbor relationships

1, Subnet mask

2 ,hell Time

3 ,dead Time

4 ,ospf Marking of special areas

5, authentication

DBD package --- Database description message --- 1, Using non data DBD The package has a master-slave relationship The election ;2, Use... That carries data DBD Package for directory information sharing .

MTu --- Huawei devices are not enabled by default MTu Value detection function , It can be used in the interface ---    [r1-serial4/0/0]ospf mtu-enable  To open ---- If both sides are open MTU It's worth it Detection function , Then both parties MTU Values must be the same , The difference will remain exstart shape      state , Cannot go down .

1 --- init --- This location 1, It stands for this DBD Package is the data for the election of master-slave relationship package , therefore , Such a packet does not contain LsA Head content .   --- In the master-slave relationship Before it is selected , All devices consider themselves Masters

M --- more --- This location 1, It means there are others behind DBD Package to send .   Ms --- Master --- This location 1, It means that the device sending this packet is the main .

Serial number --- stay DBD In the process of message sending and receiving , Will add... One by one 1, Used to ensure that DBD message Order and reliability of transmission .

LsR package --- Link status request message --- be based on DBD Package request local unknown LsA Information

Link state type , Link state 1D, Notify router ----   "LsA A triple " --- through Three parameters can uniquely identify one LsA.

Lsu package --- Link state update message   ---- Really carry LsA Packets of information

LsAcK package --- Link status acknowledgement message

ospF The interface network type of

p2p           MA           BMA           NBMA

ospF The interface network type of --- refer to ospf The interface defaults to Different ways of working .

 

[r2]display ospfinterfaceGigabitEthernet0/0/0 --- see OsPF Interface network of Network type

T1 --- 1.544Mbps

E1 --- 2.048Mbps ---- By default, the serial port of Huawei devices follows E1 standard .

Huawei equipment defines the cost value of the loopback interface as 0, Will not be affected by the outside world , Not referenced

The impact of bandwidth changes .

[r2-LoopBack0]ospf network-typebroadcast  --- Modify the interface network type

If you want to restore the true mask length of the loopback interface , The network type that can be looped back to the interface

It is amended as follows broadcast.

Huawei equipment will tunnel The transmission rate of the interface is defined as 64Kbps ---- Huawei equipment is set like this The main purpose of the design is to increase the overhead value of the tunnel interface , Make the data avoid from The tunnel interface sends , Because the data of tunnel interface , The reality is still sent from the physical interface , But it will increase the complex process of packaging and unpacking , Increase the waste of resources .

stay MGRE In the environment of , There is also a fully connected mesh topology --- mesh, Is all the boundaries The equipment is the center , Also Branch , Built like this MGRE The environment is similar    BMA Network environment .

[r1-ospf-1]peer 12.0.0.2 --- Unicast neighbors , stay NBMA Environment can be manually specified Neighborhood .

Attempt --- Try status --- Transition state --- After the local side manually specifies the neighbor, it will start from      down Reach the trial state , after , After the opposite end is manually specified, it will enter the next state .