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15 votes
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SNMP v2: What is the difference between SNMP v2c and SNMP v2u

SNMPv2u is a user-based security model, as specified in RFC 1909 and RFC 1910. SNMPv2c is a common community-based security model. SNMP 2u offers per-user authentication, similar to SNMPv3. SNMPv2u ...
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9 votes

net-snmp Creating my own MIB: No Such Instance currently exists at this OID

I think your issue is coming from a simple misconception of how SNMP data (OIDs) is structured, and how snmpwalk, snmpget, and snmpgetnext interact with it. SNMP organizes the OIDs into related ...
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9 votes
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What exact does MIB represent in SNMP? How is it different from OID?

The MIB is the entire catalog of OIDs (for a particular device). An OID is a specific reference to an individual item within the MIB. An analogy: The MIB is like the phone book for my city. The OID ...
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8 votes
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Generate list of subnets on switch using SNMP?

Interfaces/IP Addressing: If you're looking to poll a device's IP address, subnet mask and corresponding interface you can use the following OIDs from the IP-MIB and IF-MIB MIBs: .1.3.6.1.2.1.4.20.1....
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8 votes
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Is there an SNMP MIB for Cisco Track Objects

I don't believe there is a way to directly poll the results of the OR via SNMP, but you can certainly poll for the IP SLA results and calculate it yourself. Using the CISCO-RTTMON-MIB (1.3.6.1.4.1.9....
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6 votes
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Measurement of Traffic Parameters using SNMP

First, do 'Octets' in ifInOctets and ifOutOctets actually refer to packets? Can someone explain in detail? ifInOctets and ifOutOctets refer to bytes received and transmitted (respectively) by the ...
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6 votes
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SNMP IF-MIB stats export interval in Cisco IOS

Is this native to the 1900 series to only update the SNMP agent (forgive me if this is the wrong terminology) like it is doing at the moment. What you're seeing is expected behavior. IOS has ...
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6 votes
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Unpredictable Juniper SNMPv3 Access Error

This issue is a result of the engine-id changing. If you run into this syslog message, that is the exact definition of the problem. Nov 6 09:44:35 MHN00416AN01 snmpd[1260]: SNMPD_ENGINE_ID_CHANGED:...
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6 votes
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When does the Cisco IOS SNMP "ifCounterDiscontinuityTime" counter change?

The ifCounterDiscontinuityTime is triggered when interfaces are dynamically removed from a device and then that same interface is dynamically re-added. I tested this using a loopback interface but I ...
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6 votes
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Under which circumstances Cisco IOS interface SNMP counters start from zero?

SNMP counters will not be cleared while the device is up. The idea is that the software polling the counters will keep a tally of the current counter and simply looks at the delta since the last poll. ...
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  • 1,373
6 votes

What is the length of SNMP sysUpTime counter?

sysUpTime is a 32-bit counter and will roll over after 496 days. snmpEngineTime (.1.3.6.1.6.3.10.2.1.3) which returns the uptime in seconds and should not roll over for 135 years. snmpwalk -v2c -c ...
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  • 293
6 votes
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Juniper EX4200 How to read SNMP traffic counters for specific VLAN id from trunk interface?

Sadly the EX4200 (or any EX) is not able to do this. You would need a separate logical unit for the VLAN which has its own VLAN counters. This works for example on Junipers MX routers but not on EX. ...
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6 votes
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Is there a test/example/dummy SNMP trap OID?

As jonathanjo said in his answer and the comments afterwards, there are no special test traps for testing connectivity. Often, one of the RFC-defined traps (like linkup, linkdown or warmstart) is used....
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6 votes
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SNMP object not in the MIB

is it possible to add support for an OID that is not there by default? Unfortunately, adding support for these OIDs would require each of your vendors (Brocade and Dell) to implement them in their ...
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6 votes
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Why can't get host's mac address on l2 switch through snmp? But can get it on l3 router

A layer-2 switch does not look at the layer-3 IP address on a packet to switch the layer-2 frames, and it only uses the MAC addresses on the frames for switching. The layer-3 interface on the switch ...
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5 votes

Is there an SNMP MIB for Cisco Track Objects

We had the same issue and I found solution for it: It is called Expression MIB as per RFC 2982. You can do logical OR on this level by creating of new SNMP OID object which will be calculated at the ...
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5 votes

monitoring bandwidth with ifHCOutOctets / ifHCInOctets

The unit for ifSpeed is bits per second. This is in the description of the ifSpeed OID, down at the bottom of the link you supplied.
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  • 525
5 votes
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Incoming/Outgoing Traffic of LACP trunk

Your SNMP index may not match your port number. On some platforms, the indexes are not even persistent across reloads unless configured to be. I'd expect to find an interface speed of 2Gbps in your ...
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5 votes

Getting the successor of a switch depending on its spanning tree

STP has a series of steps it uses to determine which paths are used and not used. Your question has already been asked and answered here: "Not sure how much you know about switching and spanning ...
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5 votes
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Getting the successor of a switch depending on its spanning tree

If you can't access the switches there's not much you can do. Switches don't modify the Ethernet frames. Even if you could query snmp mibs (to me, that's called having access), you would have to ...
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5 votes
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What is the length of SNMP sysUpTime counter?

Did a quick test and it looks like the data is a type 'Timeticks' which is a 32 bit integer. From the RFC: The TimeTicks type represents a non-negative integer which represents the time, modulo 2^32 (...
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5 votes
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Under which circumstances SNMP interface index(ifIndex) in Cisco IOS changes?

Adding or removing physical interfaces Adding or removing logical interfaces (vlan, dialer, tunnel, etc.) In short, anything that changes the number (or order) of IDB entries. The index starts at one ...
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5 votes
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How do I monitor traffic on a subinterface Cisco 1941W

rtr1841#show snmp mib ifmib ifindex Loopback1: Ifindex = 10 Tunnel0: Ifindex = 5 Serial0/0/0: Ifindex = 7 FastEthernet0/1: Ifindex = 2 FastEthernet0/0.2: Ifindex = 8 Loopback0: Ifindex = 6 Null0: ...
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5 votes
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LAN side 1Gb link showing WAN 4Mbps throughput in SNMP

So why isn't the bandwidth capture reflect at port1 on the LAN side showing more then 4Mbps ? Because your traffic is mostly TCP, and TCP will slow down as the ISP drops traffic (due to the cap). So ...
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5 votes
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Unable to see packet drops on tunnels

The bandwidth command is simply a label for things like routing protocols and QoS. It does not change the bandwidth on the interface. If you want it to drop packets above 10 Mbps, you can create a ...
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5 votes

IfInDiscards and IfOutDiscards counters

As RFC2863 / IF-MIB describes: The number of inbound/outbound packets which were chosen to be discarded even though no errors had been detected to prevent their being deliverable to a higher-layer ...
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5 votes
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what are the difficulties of configuring switches through SNMP?

Questions that generate mostly opinion-based answers are off limits here, so we can’t really talk about why someone should or shouldn’t do something like this. As far as purely technical points go, if ...
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  • 4,436
4 votes

What do input discards on switch ports indicate and how can one track down their cause?

Unknown VLANs are the primary cause of Input Discards (ifInDiscards) in my environment; usually from inappropriate VLANs spanning a trunk port. Depending on the services active in the VLAN in ...
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  • 5,449
4 votes
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Troubleshoot SNMP - NPEG2 - Purpose of snmp mib community-map <community> engineid command

snmp mib community-map To associate a Simple Network Management Protocol (SNMP) community with an SNMP context, engine ID, or security name, use the snmp mib community-map command in global ...
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4 votes
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Need help to understand whats transmited over SNMP when i use the ipNetToPhysicalEntry OID

In addition to Ricky's answer, you can also use the snmptranslate utility to dump information about SNMP tables and how table entries are indexed, etc. The -Tp -IR flags will tell snmptranslate to ...
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