IP-NAT-MIB

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Organization: CommWorks Corporation, a 3Com Company

Last Updated: 2002-05-05

Category: CommWorks / 3Com Broadband, IP Routing & Forwarding

Description: Defines SNMP management objects for configuring and monitoring Network Address Translation on CommWorks (3Com) broadband gateways.

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What Is IP-NAT-MIB?

IP-NAT-MIB is a vendor-specific MIB from CommWorks, a 3Com subsidiary, defining management objects for Network Address Translation on its broadband gateway/router products. It exposes a NAT session table tracking each active translated flow, including source, destination, and translated IP addresses and ports, the protocol in use, and traffic direction, along with a general NAT version object. This is a software/service-state MIB rather than a hardware-health MIB: it lets an operator monitor the operational status of the NAT function itself, such as how many sessions are active and whether specific translations are behaving as expected, which is useful for diagnosing connectivity failures or session-table exhaustion on a broadband gateway. It is a self-contained vendor MIB with no apparent dependency on standard IETF NAT-MIB definitions, despite covering similar ground. It is typically deployed on 3Com/CommWorks broadband access routers and gateways providing NAT for subscriber or branch-office traffic. Engineers can download the IP-NAT-MIB file directly to load it into their MIB browser.

IPNetwork Monitor allows you to monitor SNMP objects defined in IP-NAT-MIB. Use the built-in SNMP Monitoring Browser to explore available variables, view their current values and descriptions, and select the objects you want to monitor. You can then create SNMP monitors, configure thresholds, and receive alerts when monitored values change.

Supported Devices

3Com/CommWorks broadband gateway/router

Monitoring Examples

An operator would poll ipNatSessTable/ipNatSessEntry, indexed by ipNatSessIndex, to inspect ipNatSessSrcIpAddress, ipNatSessDestIpAddress, and ipNatSessTransIpAddress for a specific session, confirming a client's traffic is being translated to the expected public address. ipNatSessSrcPort/ipNatSessDestPort/ipNatSessTransPort together with ipNatSessProtocol and ipNatSessDirection would reveal whether a particular application's NAT session is established correctly or missing entirely when connectivity fails. A rapidly growing session table could indicate exhaustion of available NAT port/session resources.

What Can Be Monitored

active NAT sessions
source/destination/translated IP address and port per session
NAT protocol and traffic direction
NAT software version

Imported Objects

From SNMPv2-SMI

Counter32
Integer32
IpAddress
MODULE-IDENTITY
OBJECT-TYPE

From USR-DEFINITIONS-MIB

UsrDisplayString
common	OBJECT-IDENTITY

How to Use in IPNetwork Monitor

Example using ipNatStatsSessSuccess OID:

Select a 3Com/CommWorks broadband gateway/router (NAT sessions) as the target host to create a monitor — the SNMP service should be up and running on it. Click New Monitor, then check SNMP Custom on the Favorites tab, click Next, and confirm the host. On the next page, click Select... to open the built-in SNMP MIB Browser and type ipNatStatsSessSuccess into the Find box to locate it in the OID tree, selecting the specific row/instance you want to monitor since this is a table column, then select it and click OK. The number of NAT sessions that have been successfully created. On the monitor's Main parameters page you can set the target's SNMP port (default 161), credentials, polling interval, and other settings — see the SNMP Monitor help for details. On the State conditions and Alerting tabs, configure when the monitor should change state and trigger an alert; since this is a Counter32-type OID, Value bounds is the most useful condition here — trigger an alert if the counter increases sharply between polls relative to its normal baseline, since an unexpected spike often reflects a real change in traffic or activity. Click Finish to create the monitor; you can adjust any parameter later.

OIDs

OID symbolic	OID numeric	Type	Access	Description
usripNat	1.3.6.1.4.1.429.4.78			The commWorks enterprise defined MIB objects for Network Address Translation.
STR ipNatVersion	1.3.6.1.4.1.429.4.78.1	UsrDisplayString	read-only	The current software version of the NAT application.
ipNatSessTable	1.3.6.1.4.1.429.4.78.2		not-accessible	The table of NAT sessions.
ipNatSessEntry	1.3.6.1.4.1.429.4.78.2.1		not-accessible	An entry for one NAT session.
I32 ipNatSessIndex	1.3.6.1.4.1.429.4.78.2.1.1	Integer32	read-only	The index value which indentifies the NAT session to which this entry is applicable.
IP ipNatSessSrcIpAddress	1.3.6.1.4.1.429.4.78.2.1.2	IpAddress	read-only	The source IP Address of the packet that initiated the flow associated with this NAT session.
IP ipNatSessDestIpAddress	1.3.6.1.4.1.429.4.78.2.1.3	IpAddress	read-only	The destination IP Address of the packet that initiated the flow associated with this NAT session.
IP ipNatSessTransIpAddress	1.3.6.1.4.1.429.4.78.2.1.4	IpAddress	read-only	The translation IP Address used by this NAT session.
INT ipNatSessProtocol	1.3.6.1.4.1.429.4.78.2.1.5	INTEGER	read-only	The value of icmp(1) indicates that this NAT session is using ICMP The value of tcp(6) indicates that this NAT session is using TCP The value of udp(17) indicates that this NAT session is using UDP
INT ipNatSessDirection	1.3.6.1.4.1.429.4.78.2.1.6	INTEGER	read-only	The direction of the packet that initiated the flow associated with this NAT session.
I32 ipNatSessSrcPort	1.3.6.1.4.1.429.4.78.2.1.7	Integer32	read-only	For UDP and TCP NAT sessions, the source port number of the packet that initiated the flow associated with this NAT session. For neither UDP nor TCP NAT sessions this value is 0.
I32 ipNatSessDestPort	1.3.6.1.4.1.429.4.78.2.1.8	Integer32	read-only	For UDP and TCP NAT sessions, the destination port number of the packet that initiated the flow associated with this NAT session. For neither UDP nor TCP NAT sessions this value is 0.
I32 ipNatSessTransPort	1.3.6.1.4.1.429.4.78.2.1.9	Integer32	read-only	For UDP and TCP NAT sessions, the translation port number of this NAT session. For neither UDP nor TCP NAT sessions this value is 0.
I32 ipNatSessLifetime	1.3.6.1.4.1.429.4.78.2.1.10	Integer32	read-only	The number of seconds that this translation session has existed.
ipNatStatsTable	1.3.6.1.4.1.429.4.78.3		not-accessible	The table of NAT statistics.
ipNatStatsEntry	1.3.6.1.4.1.429.4.78.3.1		not-accessible	An entry for one NAT session.
I32 ipNatStatsIndex	1.3.6.1.4.1.429.4.78.3.1.1	Integer32	read-only	The index value which indentifies the set of statistics. INCOMING(2) or outgoing(1)
C32 ipNatStatsSessSuccessEx	1.3.6.1.4.1.429.4.78.3.1.2	Counter32	read-only	The number of NAT sessions that have been successfully created.
C32 ipNatStatsSessFail	1.3.6.1.4.1.429.4.78.3.1.3	Counter32	read-only	The number of NAT sessions attempts that have been failed due to either the maximum number of N discarded.
C32 ipNatStatsInTransPkts	1.3.6.1.4.1.429.4.78.3.1.4	Counter32	read-only	The number of INCOMING packets that have been successfully translated.
C32 ipNatStatsInDiscards	1.3.6.1.4.1.429.4.78.3.1.5	Counter32	read-only	The number of INCOMING packets that have been discarded.
C32 ipNatStatsOutTransPkts	1.3.6.1.4.1.429.4.78.3.1.6	Counter32	read-only	The number of outgoing packets that have been successfully translated.
C32 ipNatStatsOutDiscards	1.3.6.1.4.1.429.4.78.3.1.7	Counter32	read-only	The number of outgoing packets that have been discarded.

RFC description

3Com CommWorks Network Address Translation (NAT) MIB for monitoring NAT sessions and translating IP addresses and ports.

Start monitoring 3Com/CommWorks broadband gateway/router (NAT sessions) with a free 30-day trial of IPNetwork Monitor. Import MIBs, browse SNMP OIDs, create custom SNMP monitors, configure alerts, and monitor any SNMP-enabled network device from a single console.

Download IP-NAT-MIB