Hitachi Microlok II, Installation, Operation And Troubleshooting Manual

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Microlok II
®
Serial-to-Ethernet Converter (SEC)
Copyright 2019 SM6800O Rev. 1, March 2019 5-7
In this example, SEC A connects to SEC B at 192.168.1.17 on port 4001 because SEC A's IP
address is less than SEC B's IP address. SEC B accepts a connection from SEC A on port
4001 because SEC B's IP address is greater than SEC A's IP address. (See Section 5.3.2.1.)
In other words, SEC B waits for a TCP connection from 192.168.1.16 on port 4001. SEC A
connects to 192.168.1.17 on port 4001.
Once a TCP connection is established, Peer messages can flow in both directions on the
TCP link.
5.3.2.1 TCP Client/Server Strategy
If the target IP is greater than the local IP, then it will try to connect to the target IP. If the
local IP is greater than the target, then it will accept a connection from the target IP.
MICROLOK II A
STATION_1
MII. ADDRESS: 10
PEER. ADDRESS: 20
MICROLOK II B
STATION_2
MII. ADDRESS: 20
PEER. ADDRESS: 10
SEC
A
SEC
B
192.168.1.16
(IP ADDRESS)
192.168.1.17
(IP ADDRESS)
SEC A connects to SEC B at 192.168.1.17 on port 4001.
SEC B accepts a connection on port 4001 from SEC A at 192.168.1.16.
4001:192.168.1.16:4001 = 000A
6001:192.168.1.17:4001 = 0014
<mlk_ addr_list>
<target_ip_addr>
<target_port>
<local_port>
TCP/IP
NETWORK
Figure 5-1 - An Example of a the Format for TCP Communication
5.4 HMAC Section Options
HMAC, or a Hash-keyed Message Authentication Code, provides a way to check the integrity
of data sent through the communication links. HMAC only works with the (TCP) static routing
table. It provides integrity checking based on “Message Authentication Codes” (MAC). MACs
are used between two parties that share a secret key so that the information transmitted
between these two parties can be validated.
HMAC adds a message authentication protocol on top of the Peer protocol. A Key Server is
required for this function to work. When HMAC is enabled, all messages are sent
encapsulated with the HMAC protocol.