Motorola V186 - Cell Phone - GSM System Planner Manual page 110

• Static IP address mode
• Dynamic (DHCP)
With static IP address mode, the user is required to set the link ID, IP address, subnet
mask and default gateway. If DNS or NTP servers are required, these must be defined as
well. DNS servers are only required if this port is to be accessed via a host name rather
than a numeric IP address. In this case the operator assigns a host domain name to the
FEP or RTU. The IP conversion table must include the domain name well. If an NTP
server is to be used to obtain the time, the numeric IP address or domain name of the
NTP server must be defined.
In DHCP address mode, the user is only required to set the link ID for this port. If DNS
servers are required there is no need to set them, since they are learned from the network.
If NTP servers are required, the user must set them since they are not learned from the
network.
As an option, user can set a full host domain name for an Ethernet port that is configured
as a dynamic DHCP client. Each port should be set with a different name. This option
allows the network DNS servers to be updated when the DHCP server changes its IP
address, keeping its name up to date. This is called FQDN and is not always supported by
the DHCP server (in this case a warning is logged.)
MDLC over IP Site Paging
A paging mechanism is available in each site (peer) to make MDLC over IP more
reliable. (This feature is the same as in Toolbox V9.54 and MOSCAD V9.25.) Paging a
site before transmitting MDLC data to it over IP, guarantees that the site is reachable.
This is necessary because MDLC over IP does not have a confirmed type of link in which
the peer acknowledges received packets (as opposed to other types of MDLC ports). It
relies on the radio to have a link layer that will guarantee a 'best effort' delivery, and thus
avoids overloading the channel with excessive traffic.
A site is paged by sending it a poll request and awaiting a poll reply. During this time, the
RTU can continue to transmit to other sites (and receive transmission from other sites). If
the site responds with a poll reply, or any other MDLC data, it is considered as reachable
and all pending transmissions are sent to it immediately. Further transmissions will be
sent to it as well without paging until the site is declared as failed.
If an 'ICMP Destination Unreachable' message is received or if the site does not respond
to paging for a configurable poll interval, it will be polled again for a maximum number
of polls. If there is still no response, the site is considered to be failed, and the network
layer is notified so any pending transmissions can be redirected to an alternative route. If
subsequent transmissions are to be sent to the site through an MDLC over IP port, paging
will be performed again before actual transmission takes place. The Site Paging
mechanism can be enabled or disabled.
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Communications