What is a network protocol? arp Why is an entry-level agreements?
网络协议指的是计算机网络中互相通信的对等实体之间交换信息时所必须遵守的规则的集合When the network has data to send to another network device, it is necessary to know each other's network layer address (i.e., IP address). IP address is provided by the network layer, but only the IP address is not enough, IP packets are encapsulated in frames transmitted over the data link. Data frame comprising a destination MAC address must be available, the transmitter must also be obtained destination MAC address
Role: ip address known to the other party, the other party to get the mac address
because the host before sending the data package will be found in the package to the second floor when the DMAC address this one I can not get my host side sends a request broadcast packets after receiving the reply know out message corresponding host I able to complete the package, and the data sent
Master general arp, free arp, arp proxy role
ARP of ordinary working process
The first step: Host A and Host C want to communicate
Step two: Host A will query its ARP cache table
The ARP cache tables according to different host systems, the time will be different cache, cache time among the windows system is about 20 minutes
The third step: ARP request broadcast by Host A sends (the REQUEST)
Step Four: The target host receives the appropriate reply ARPREPAY
NOTE: At this time the target host is also stored in the corresponding cache host A table inside the IP address and corresponding MAC address
Step five: Host A receives the reply of the target host
Free ARP
Host is assigned an IP address or IP address after the change occurs, you must immediately detect its assigned IP address on the network if only to avoid address conflicts
Function 1: Check the IP address configuration for conflicts
We configured the IP address in AR2 of G0 / 0/2 Interface
[R2-GigabitEthernet0/0/2]ip address 192.168.1.2 24
Nov 13 2019 11:40:42-08:00 R2 %%01IFNET/4/LINK_STATE(l)[0]:The line protocol IP
on the interface GigabitEthernet0/0/2 has entered the UP state.
[R2-GigabitEthernet0/0/2]dis this
[V200R003C00]
#
interface GigabitEthernet0/0/2
ip address 192.168.1.2 255.255.255.0
#R2 is in the G0 / 0/2 interfaces capture
At this time, the IP address of AR1 are also arranged 192.168.1.2/24, to view the following information
[R1-GigabitEthernet0/0/1]ip address 192.168.1.2 24 Nov 13 2019 11:47:59-08:00 R1 %%01IFNET/4/LINK_STATE(l)[0]:The line protocol IP on the interface GigabitEthernet0/0/1 has entered the UP state. [R1-GigabitEthernet0/0/1] Nov 13 2019 11:48:01-08:00 R1 ARP/4/**ARP_IPCONFLICT**_TRAP:OID 16777216.50331648.10 0663296.16777216.67108864.16777216.3674669056.83886080.419430400.2063597568.3355 4432.100663296 ARP detects IP conflict. (IP address=2.1.168.192, Local interface =GigabitEthernet0/0/1, Local MAC=00e0-fc5d-1f32, Local vlan=0, Local CE vlan=0, Receive interface=GigabitEthernet0/0/1, Receive MAC=00e0-fcb1-5891, Receive vlan =0, Receive CE vlan=0, IP conflict type=Local IP conflict). [R1-GigabitEthernet0/0/1] Nov 13 2019 11:48:01-08:00 R1 %%01ARP/4/ARP_DUPLICATE_IPADDR(l)[1]:Received an A RP packet with a duplicate IP address from the interface. (IpAddress=2.1.168.192 , InterfaceName=GigabitEthernet0/0/1, MacAddress=00e0-fcb1-5891) [R1-GigabitEthernet0/0/1]And will find that when the address conflict, the above link will continue to have issued the gratuitous ARP, sent once every 5s
Two functions: MAC address of the switch table refresh (VRRP at the scene)
If the state after the failure of the device occurs becomes Master Master, it sends gratuitous ARP packets to refresh MAC entries on the switch, so that the user traffic to this device up, the whole process completely transparent to users.
Proxy ARP
Huawei is not turned on by default
enable proxy ARP
interface GigabitEthernet0/0/0
arp-proxy enableSolve the problem
In the scene without providing a gateway to achieve access to different network segments
Routed Proxy ARP is possible to enable a feature that communicate with each other on the same subnet is not on the same physical network devices of network
PC1的MAC地址：54-89-98-24-42-29
PC2的MAC地址：54-89-98-B7-79-9D
AR1的G0/0/0接口MAC地址：00e0-fc31-53e4
AR1的G0/0/1接口MAC地址：00e0-fc31-53e5
AR1上面的配置
#
interface GigabitEthernet0/0/0
ip address 172.16.1.254 255.255.255.0
arp-proxy enable
#
interface GigabitEthernet0/0/1
ip address 172.16.2.254 255.255.255.0
arp-proxy enable
#
Analyze the entire process PC1 access PC2 is kind of how?
Static routing uses the interface scene
As shown in FIG: AR1 and AR3 in each static route configured as follows? I ask: AR1 and AR3 be able to access the IP address it?
如果访问不了？请给出说明的原因？需要通过什么方式的修改才能进行访问？
在AR2上面开启arp-proxy功能
#
interface GigabitEthernet0/0/0
ip address 12.1.1.2 255.255.255.0
arp-proxy enable
#
interface GigabitEthernet0/0/1
ip address 23.1.1.2 255.255.255.0
arp-proxy enable
#
R2设备的各个接口的MAC地址
AR2设备接口的G0/0/0的MAC地址：00e0-fc60-2626
AR2设备接口的G0/0/1的MAC地址：00e0-fc60-2627
查看AR1设备的ARP表项：
<R1>display arp
IP ADDRESS MAC ADDRESS EXPIRE(M) TYPE INTERFACE vVpPnN-INSTANCE
VLAN/CEVLAN PVC
------------------------------------------------------------------------------
12.1.1.1 00e0-fc01-5a32 I - GE0/0/0
23.1.1.3 00e0-fc60-2626 17 D-0 GE0/0/0
12.1.1.2 00e0-fc60-2626 17 D-0 GE0/0/0
------------------------------------------------------------------------------
Total:3 Dynamic:2 Static:0 Interface:1
查看AR3的ARP表项
<R3>display arp
IP ADDRESS MAC ADDRESS EXPIRE(M) TYPE INTERFACE vVpPnN-INSTANCE
VLAN/CEVLAN PVC
------------------------------------------------------------------------------
23.1.1.3 00e0-fcf2-675a I - GE0/0/1
23.1.1.2 00e0-fc60-2627 17 D-0 GE0/0/1
12.1.1.1 00e0-fc60-2627 17 D-0 GE0/0/1
------------------------------------------------------------------------------
Total:3 Dynamic:2 Static:0 Interface:1 Encapsulation and decapsulation of data transfer between two computers during the inter-network
