Comtech EF Data MM200 - Manual (Page 62)

User Interfaces MM200 High-Speed Microwave Modem
4-38 TM086 - Rev. 4.1
4.5.7 RLLP Summary
The RLLP is a simple send-and-wait protocol that automatically re-transmits a packet
when an error is detected, or when an acknowledgment (response) packet is absent.
During transmission, the protocol wrapper surrounds the actual data to form information packets.
Each transmitted packet is subject to time out and frame sequence control parameters, after
which the packet sender waits for the receiver to convey its response. Once a receiver verifies
that a packet sent to it is in the correct sequence relative to the previously received packet, it
computes a local checksum on all information within the packet excluding the character
and the fields. If this checksum matches the packet , the receiver
processes the packet and responds to the packet sender with a valid response (acknowledgment)
packet.
The response packet is therefore either an acknowledgment that the message was received
correctly. If the sender receives a valid acknowledgment (response) packet from the receiver, the
increments and the next packet is transmitted as required by the sender.
If an acknowledgment (response) packet is lost, corrupted, or not issued due to an error and is
thereby not returned to the sender, the sender re-transmits the original information packet; but
with the same . When the intended receiver detects a duplicate packet, the packet is
acknowledged with a response packet and internally discarded to preclude undesired repetitive
executions. If the M&C computer sends a command packet and the corresponding response
packet is lost due to a system or internal error, the computer times out and re-transmits the same
command packet with the same to the same receiver and waits once again for an
acknowledgment.
Refer to Appendix A for RLLP.
4.6 Simple Network Management Protocol (SNMP)
Simple Network Management Protocol (SNMP), as its name suggests, is a relatively simple
protocol by which management information for a network device may be inspected and/or altered
by remote administrators.
4.7 The Management Information Base (MIB)
Management objects are defined in the Management Information Base (MIB), which uses a
hierarchical naming scheme. Within this scheme, each object is identified by an Object Identifier
(OID), a sequence of non-negative integers that uniquely describes the path taken through the
hierarchical structure.
MIB objects may then be specified either from the Root (which has no designator), or alternatively
from anywhere within the hierarchical structure.
For example: 1.3.6.1.4.1.2591.4 is equivalent to {iso(1). org(3). dod(6). internet(1). private(4).
enterprises(1). Radyne(2591). RCS10L(4)} (See Figure 1).
In general, we are mainly concerned with just two groups that reside in the internet subtree,
namely the mgmt, and private groups. For completeness however, the four major groups are
discussed below:
4.8 Directory {internet 1} 1.3.6.1.1
This area was reserved to describe how the OSI directory structure may be used in the Internet.
To date this has not been implemented and therefore is of little interest to us.