Udp Relay - Vocality V100 Technical Manual

C H A P T E R 4 F E A T U R E S

4.13.9 UDP Relay

Standard IPV4 router operation does not allow for the forwarding of subnet broadcasts. However certain
network applications rely on the relay of UDP packets sent to the subnet broadcast address. For example
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Windows browsing service relies on Netbios datagram service packets (addressed to UDP port 138 and
the IP subnet broadcast address) reaching all stations within the browsing domain. To allow seamless
operation of such applications across the IP ports of a V100 network, the ability to relay UDP subnet
broadcasts has been provided. To enable such operation the UDPGw configuration must be turned to "On"
for each port that we wish the relay operation to work on. Additionally, an entry in the UDP relay table
must be added for each service that must be relayed. Some well-known service types are pre-configured
for addition to this table – other services require the appropriate UDP port number to be configured. The
example configurations shown in below show the configuration required to relay NetBIOS datagrams (UDP
port 138) and subnet broadcasts to UDP port 200 between the Ethernet and V100 channel 0:11 (but not
to 0:10). Note the "NetBIOS Name" and "Domain Name" ports have also been included since they will be
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required to get legacy Windows networking working smoothly:
Example IP Network configuration for UDP relay
When using UDP relay care must be taken to ensure that broadcast loops are not introduced into the
network. The V100 will ensure that the affects of such loops are minimized through TTL reduction, but
network operation will still be adversely affected.
V100 Versatile Multiplexer Technical Manual Version 2.2
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