- Cabletron IP Router Reference Guide

Introduction
1-5
1.4 SNMP PRIMITIVES
The major software interface between the NMS and ELS10-26
consists of one simple mechanism – the exchange of SNMP (Simple
Network Management Protocol, RFC 1157) datagrams over any
available physical media. The following restrictions apply:
• All datagrams must obey SNMP format.
• All datagrams must be sent via UDP and IP. Thus, all datagrams
will have UDP and IP headers.
• Datagrams may be sent over any of the following physical
media:
- Ethernet/802.3 LAN - the datagram must have an Ethernet
MAC header, with an Ethernet frame type of IP; or, the
datagram must be in 802.3 format with IP-encapsulation as
defined by RFC 1042.
- UART (out-of-band management port) - the datagram must
have a PPP header, which indicates that the datagram
contains an IP packet. (The ELS10-26 automatically detects
the presence of a PPP connection versus being connected to
a non-intelligent terminal.)
The NMS must rely on IP, rather than MAC addressing for all
datagrams sent to an ELS10-26. Therefore:
• All datagrams from the ELS10-26 are addressed to either an
NMS or the broadcast IP address.
• Within the context of this document, the terms “datagram,”
“packet,” and “PDU” are synonymous.