SNMP Agent Implementation
This feature implements a Simple Network Management Protocol (SNMP) agent on each IP card that runs the ss7ipgw, ipgwi, iplim, or iplimi applications. SNMP is an industry-wide standard protocol used for network management. SNMP agents interact with network management applications called Network Management Systems (NMSs).
Supported Managed Object Groups
The SNMP agent maintains data variables that represent aspects of the IP card. These variables are called managed objects and are stored in a management information base (MIB). The SNMP protocol arranges managed objects into groups. Table 2-6 shows the groups that are supported.
Table 2-6 SNMP Object Groups
| Group Name | Description | Contents |
|---|---|---|
|
system |
Text description of agent in printable ASCII characters |
System description, object identifier, length of time since reinitialization of agent, other administrative details |
|
interfaces |
Information about hardware interfaces on the IP card |
Table that contains for each interface, speed, physical address, current operational status, and packet statistics |
|
ip |
Information about host and router use of the IP |
Scalar objects that provide IP-related datagram statistics, and 3 tables: address table, IP-to-physical address translation table, and IP-forwarding table |
|
icmp |
Intranetwork control messages, representing various ICMP operations within the IP card |
26 scalar objects that maintain statistics for various Internet Control Message Protocol (ICMP) messages |
|
tcp |
Information about TCP operation and connections |
14 scalar objects that record TCP parameters and statistics, such as the number of TCP connections supported and the total number of TCP segments transmitted, and a table that contains information about individual TCP connections |
|
udp |
Information about UDP operation |
4 scalar objects that maintain UDP-related datagram statistics, and a table that contains address and port information |
|
snmp |
Details about SNMP objects |
30 scalar objects, including SNMP message statistics, number of MIB objects retrieved, and number of SNMP traps sent |
Supported SNMP Messages
The SNMP agent interacts with up to two NMSs by:
- Responding to Get and GetNext commands sent from an NMS for monitoring the IP card.
- Responding to Set commands sent from an NMS for maintaining the IP card and changing managed objects as specified.
- Sending Trap messages to asynchronously notify an NMS of conditions such as a link going up or down. Traps provide a way to alert the NMS in a more timely fashion than waiting for a Get or GetNext from the NMS. Two hostnames, DCMSNMPTRAPHOST1 and DCMSNMPTRAPHOST2, are utilized to specify the SNMPNMS to which traps are sent. In this release, only the following traps are supported:
- coldStart, sent one time only when the IP stack initialization occurs on the IP card as part of boot processing
- linkUp, sent when one of the ports on the IP card initially comes up or recovers from a previous failure
- linkDown, sent when one of the ports on the IP card fails
When a trap occurs at the IP card agent, the agent sends the trap to each of the SNMP specific host names that can be resolved to an IP address. Resolution is based on configuration data in the chg-ip-card command (or default data) which specifies DNS search order and DNS information.
Deviations from SNMP Protocol
Table 2-7 shows how the EAGLE deviates from the standard SNMP protocol definition.
Table 2-7 Deviations from SNMP Protocols
| Group | Variable Name | Usage | Deviation |
|---|---|---|---|
|
system |
sysContact |
Text identification of contact information for agent |
Cannot be set by
Set command; may be set only by
|
|
sysLocation |
Physical location of agent |
Cannot be set by Set command; internally set using configuration data already available; set to <CLLI>-<slot of IP card> |
|
|
sysName |
Administratively assigned name for agent |
Cannot be set by Set command; internally set using configuration data already available; set to <CLLI>-<slot of IP card> |
|
|
interface |
ifAdminStatus |
Desired state of the interface |
Cannot be set by Set command (to ensure that an NMS does not disrupt SS7 traffic by placing an IP interface in a nonoperable state) |
|
ip |
ipForwarding ipDefaultTTL ipRoute Dest ipRouteIfIndex ipRouteMetric1-5 ipRouteNextHop ipRouteType iprouteAge ipRouteMask |
IP route-specific values |
Cannot be set by Set command |
|
ipNetToMediaIfIndex ipNetToMediaPhysAdress ipNetToMediaNetAddress ipNetToMediaType |
IP-address specific information |
Can be set by Set command, but not saved across IP card reloads |
|
|
tcp |
tcpConnState |
State of a TCP connection |
Cannot be set by Set command |
|
snmp |
snmpEnableAuthenTraps |
Indicate whether agent is permitted to generate authentication failure traps |
Cannot be set by Set command |