CTI Products EXB-IP Ethernet System Extender - Manual (Page 53)

CTI Products, Inc. EXB-IP User Guide
Appendix G - IP Addressing 53
IP Addressing modes
Unicast/Replicated
Unicast/Replicated addressing mode allows point-to-point or point-to-multipoint communications in any IP
network. A table of Target IP Addresses is configured into each of the EXB-IP modules. The table in each
EXB-IP module contains the IP addresses of the other modules in the group. The maximum number of EXB-IP
modules that can be configured into one Unicast/Replicated group is 96.
Each EXB-IP module is programmed with a Host IP Address, a list of Target IP Addresses, and optionally, a
Default Gateway IP Address. The Default Gateway IP Address is the address of the IP router to which the
respective EXB-IP module is attached and allows for IP routers or gateways that may exist between EXB-IP
modules.
Using Unicast/Replicated mode, a single MCN message packet entering any of the EXB-IP modules of the
group will be sent out the Ethernet port of that module as multiple Unicast IP messages, one to each of the other
EXB-IP modules in the group.
Multicast
Multicast addressing mode allows efficient point-to-multipoint communications in a network. Each EXB-IP
module is assigned a Host IP Address, a multicast Target IP Address, and optionally, a Default Gateway IP
Address. A single multicast Target IP Address is assigned to all EXB-IP modules in the network within the
range 224.0.0.1 through 239.255.255.254.
A single MCN message packet entering any one of the EXB-IP modules results in a single multicast IP packet
being sent out the Ethernet port of that module to be received by all other EXB-IPm modules (members)
configured to the same Multicast IP address.
Multicast addressing mode can be used with a very large number of EXB-IP modules. Because only one IP
packet is generated for every MCN message packet, multicast addressing mode uses far less network bandwidth
than Unicast/Replicated.
Before choosing multicast addressing mode, it is important to determine the following capabilities of the IP
network to which the EXB-IP modules will be connected:
• IP routers must be capable of handling IP multicast traffic.
• IP routers must have IP multicast enabled
• IP routers must forward multicast traffic from the Source UDP Port of 1283 and to the appropriate
Destination UDP Port number as configured by EXB Config and.
MAC Addresses
Whereas IP uses Logical Addresses to identify a host (node), other protocols use Hardware Addresses called
Media Access Control addresses, or MAC addresses. MAC addresses are set at the factory at time of
manufacture and cannot be changed. (IP addresses can be changed at any time.) A MAC address consists of
six octets, in hexadecimal notation, separated by colons. An example would be:
00:10:EE:00:02:34.
The first three octets in a MAC address identify the manufacturer. In the above example, 00:10:EE identifies
CTI Products as the manufacturer of this device. The last three octets are sequentially assigned by the
manufacturer to form a type of serial number. In this way, no two devices have the same MAC address.
Multicast addressing is also possible using MAC addresses, just as in IP addressing. MAC addresses reserved
for broadcast messages start at: 00:01:5E:00:00:00.
Address Resolution Protocol (ARP)
Since IP uses Logical Addresses at the OSI Network Layer (Layer 3) and Ethernet uses MAC addresses at the
OSI Data Link Layer (Layer 2), Address Resolution Protocol is used whenever IP is used over the Ethernet.
ARP is needed to convert an IP address to a MAC address. The client then stores this resolved address for a