Lan Port Mirror; Nat - Draytek Vigor2820 Series User Manual

3 . 2 . 6 L A N P o
3 . 2 . 6 L A N P o
LAN Port mirror can be applied for the users in LAN. Generally speaking, this function copies
traffic from one or more specific ports to a target port. This mechanism helps manager track
the network errors or abnormal packets transmission without interrupting the flow of data
access the network. By the way, user can apply this function to monitor all traffics which user
needs to check.
There are some advantages supported in this feature. First, it is more economical without other
detecting equipments to be set up. Second, it may be able to view traffic on one or more ports
within a VLAN at the same time. Third, it can transfer all data traffics to be mirrored to one
analyzer connect to the mirroring port. Last, it is more convenient and easy to configure in
user's interface.
Port Mirror
Mirror Port
Mirrored port
3 . 3 N A T
3 . 3 N A T
Usually, the router serves as an NAT (Network Address Translation) router. NAT is a
mechanism that one or more private IP addresses can be mapped into a single public one.
Public IP address is usually assigned by your ISP, for which you may get charged. Private IP
addresses are recognized only among internal hosts.
When the outgoing packets destined to some public server on the Internet reach the NAT
router, the router will change its source address into the public IP address of the router, select
the available public port, and then forward it. At the same time, the router shall list an entry in
a table to memorize this address/port-mapping relationship. When the public server response,
the incoming traffic, of course, is destined to the router's public IP address and the router will
do the inversion based on its table. Therefore, the internal host can communicate with external
host smoothly.
The benefit of the NAT includes:
Save cost on applying public IP address and apply efficient usage of IP address.
NAT allows the internal IP addresses of local hosts to be translated into one public IP
address, thus you can have only one IP address on behalf of the entire internal hosts.
Enhance security of the internal network by obscuring the IP address. There are
many attacks aiming victims based on the IP address. Since the attacker cannot be aware
of any private IP addresses, the NAT function can protect the internal network.
r t M i r r o r
r t M i r r o r
Check Enable to activate this function. Or, check Disable to close
this function.
Select a port to view traffic sent from mirrored ports.
Select which ports are necessary to be mirrored.
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Vigor2820 Series User's Guide