"Walk" is not a strictly speaking an SNMP operation. When you talk about "walking the MIB" you are talking about sequentially retrieving values from the MIB. To sequentially retrieve MIB values, you can use:

• GET-NEXT requests in protocol versions 1, 2 or 3

"Walk" is not a strictly speaking an SNMP operation. When you talk about "walking the MIB" you are talking about sequentially retrieving values from the MIB. To sequentially retrieve MIB values, you can use:

• GET-NEXT requests in protocol versions 1, 2 or 3

takes an OID and returns the OID following the requested MIB with the value associated with it

• GET-BULK requests in protocol versions 2 and 3

also takes an OID and then returns MaxRepetitions number of MIB entries following the requested OID

If you have any choice at all, you should always use GET-BULK. It results in fewer requests and much better retrieval speed.

SNMP Version 1 GET-NEXT Example

using System;
using System.Net;
using SnmpSharpNet;
 
namespace sharpwalk
{
    class Program
    {
        static void Main(string[] args)
        {
            // SNMP community name
            OctetString community = new OctetString("public");
 
            // Define agent parameters class
            AgentParameters param = new AgentParameters(community);
            // Set SNMP version to 1
            param.Version = SnmpVersion.Ver1;
            // Construct the agent address object
            // IpAddress class is easy to use here because
            //  it will try to resolve constructor parameter if it doesn't
            //  parse to an IP address
            IpAddress agent = new IpAddress("127.0.0.1");
 
            // Construct target
            UdpTarget target = new UdpTarget((IPAddress)agent, 161, 2000, 1);
 
            // Define Oid that is the root of the MIB
            //  tree you wish to retrieve
            Oid rootOid = new Oid("1.3.6.1.2.1.2.2.1.2"); // ifDescr
 
            // This Oid represents last Oid returned by
            //  the SNMP agent
            Oid lastOid = (Oid)rootOid.Clone();
 
            // Pdu class used for all requests
            Pdu pdu = new Pdu(PduType.GetNext);
 
            // Loop through results
            while (lastOid != null)
            {
                // When Pdu class is first constructed, RequestId is set to a random value
                // that needs to be incremented on subsequent requests made using the
                // same instance of the Pdu class.
                if (pdu.RequestId != 0)
                {
                    pdu.RequestId += 1;
                }
                // Clear Oids from the Pdu class.
                pdu.VbList.Clear();
                // Initialize request PDU with the last retrieved Oid
                pdu.VbList.Add(lastOid);
                // Make SNMP request
                SnmpV1Packet result = (SnmpV1Packet)target.Request(pdu, param);
                // You should catch exceptions in the Request if using in real application.
 
                // If result is null then agent didn't reply or we couldn't parse the reply.
                if (result != null)
                {
                    // ErrorStatus other then 0 is an error returned by 
                    // the Agent - see SnmpConstants for error definitions
                    if (result.Pdu.ErrorStatus != 0)
                    {
                        // agent reported an error with the request
                        Console.WriteLine("Error in SNMP reply. Error {0} index {1}", 
                            result.Pdu.ErrorStatus,
                            result.Pdu.ErrorIndex);
                        lastOid = null;
                        break;
                    }
                    else
                    {
                        // Walk through returned variable bindings
                        foreach (Vb v in result.Pdu.VbList)
                        {
                            // Check that retrieved Oid is "child" of the root OID
                            if (rootOid.IsRootOf(v.Oid))
                            {
                                Console.WriteLine("{0} ({1}): {2}",
                                    v.Oid.ToString(), 
                                    SnmpConstants.GetTypeName(v.Value.Type), 
                                    v.Value.ToString());
                                lastOid = v.Oid;
                            }
                            else
                            {
                                // we have reached the end of the requested
                                // MIB tree. Set lastOid to null and exit loop
                                lastOid = null;
                            }
                        }
                    }
                }
                else
                {
                    Console.WriteLine("No response received from SNMP agent.");
                }
            }
            target.Close();
        }
    }
}
</pre>
<h2>SNMP Version 2 GET-BULK Example</h2>
<pre xml:lang="csharp">using System;
using System.Net;
using SnmpSharpNet;
 
namespace sharpwalk
{
    class Program
    {
        static void Main(string[] args)
        {
            // SNMP community name
            OctetString community = new OctetString("public");
 
            // Define agent parameters class
            AgentParameters param = new AgentParameters(community);
            // Set SNMP version to 2 (GET-BULK only works with SNMP ver 2 and 3)
            param.Version = SnmpVersion.Ver2;
            // Construct the agent address object
            // IpAddress class is easy to use here because
            //  it will try to resolve constructor parameter if it doesn't
            //  parse to an IP address
            IpAddress agent = new IpAddress("127.0.0.1");
 
            // Construct target
            UdpTarget target = new UdpTarget((IPAddress)agent, 161, 2000, 1);
 
            // Define Oid that is the root of the MIB
            //  tree you wish to retrieve
            Oid rootOid = new Oid("1.3.6.1.2.1.2.2.1.2"); // ifDescr
 
            // This Oid represents last Oid returned by
            //  the SNMP agent
            Oid lastOid = (Oid)rootOid.Clone();
 
            // Pdu class used for all requests
            Pdu pdu = new Pdu(PduType.GetBulk);
 
            // In this example, set NonRepeaters value to 0
            pdu.NonRepeaters = 0;
            // MaxRepetitions tells the agent how many Oid/Value pairs to return
            // in the response.
            pdu.MaxRepetitions = 5;
 
            // Loop through results
            while (lastOid != null)
            {
                // When Pdu class is first constructed, RequestId is set to 0
                // and during encoding id will be set to the random value
                // for subsequent requests, id will be set to a value that
                // needs to be incremented to have unique request ids for each
                // packet
                if (pdu.RequestId != 0)
                {
                    pdu.RequestId += 1;
                }
                // Clear Oids from the Pdu class.
                pdu.VbList.Clear();
                // Initialize request PDU with the last retrieved Oid
                pdu.VbList.Add(lastOid);
                // Make SNMP request
                SnmpV2Packet result = (SnmpV2Packet)target.Request(pdu, param);
                // You should catch exceptions in the Request if using in real application.
 
                // If result is null then agent didn't reply or we couldn't parse the reply.
                if (result != null)
                {
                    // ErrorStatus other then 0 is an error returned by 
                    // the Agent - see SnmpConstants for error definitions
                    if (result.Pdu.ErrorStatus != 0)
                    {
                        // agent reported an error with the request
                        Console.WriteLine("Error in SNMP reply. Error {0} index {1}", 
                            result.Pdu.ErrorStatus,
                            result.Pdu.ErrorIndex);
                        lastOid = null;
                        break;
                    }
                    else
                    {
                        // Walk through returned variable bindings
                        foreach (Vb v in result.Pdu.VbList)
                        {
                            // Check that retrieved Oid is "child" of the root OID
                            if (rootOid.IsRootOf(v.Oid))
                            {
                                Console.WriteLine("{0} ({1}): {2}",
                                    v.Oid.ToString(), 
                                    SnmpConstants.GetTypeName(v.Value.Type), 
                                    v.Value.ToString());
                                if (v.Value.Type == SnmpConstants.SMI_ENDOFMIBVIEW)
                                    lastOid = null;
                                else
                                    lastOid = v.Oid;
                            }
                            else
                            {
                                // we have reached the end of the requested
                                // MIB tree. Set lastOid to null and exit loop
                                lastOid = null;
                            }
                        }
                    }
                }
                else
                {
                    Console.WriteLine("No response received from SNMP agent.");
                }
            }
            target.Close();
        }
    }
}

Result of both examples

When I run either of the above examples on my notebook, I get following output:

1.3.6.1.2.1.2.2.1.2.1 (OctetString): Software Loopback Interface 1
1.3.6.1.2.1.2.2.1.2.2 (OctetString): WAN Miniport (L2TP)
1.3.6.1.2.1.2.2.1.2.3 (OctetString): WAN Miniport (PPTP)
1.3.6.1.2.1.2.2.1.2.4 (OctetString): WAN Miniport (PPPOE)
1.3.6.1.2.1.2.2.1.2.5 (OctetString): WAN Miniport (IPv6)
1.3.6.1.2.1.2.2.1.2.6 (OctetString): WAN Miniport (IP)
1.3.6.1.2.1.2.2.1.2.7 (OctetString): RAS Async Adapter
1.3.6.1.2.1.2.2.1.2.8 (OctetString): WAN Miniport (SSTP)
1.3.6.1.2.1.2.2.1.2.9 (OctetString): WAN Miniport (Network Monitor)
1.3.6.1.2.1.2.2.1.2.10 (OctetString): Realtek RTL8101E Family PCI-E FE NIC
1.3.6.1.2.1.2.2.1.2.11 (OctetString): Intel(R) PRO/Wireless 3945ABG Network Connection
1.3.6.1.2.1.2.2.1.2.12 (OctetString): Teredo Tunneling Pseudo-Interface
1.3.6.1.2.1.2.2.1.2.13 (OctetString): VMware Virtual Ethernet Adapter for VMnet1
1.3.6.1.2.1.2.2.1.2.14 (OctetString): isatap.{5D34A036-E8DD-4344-9CE3-58B461D1CB2A}
1.3.6.1.2.1.2.2.1.2.15 (OctetString): VMware Virtual Ethernet Adapter for VMnet8
1.3.6.1.2.1.2.2.1.2.16 (OctetString): isatap.{9195335D-923C-42BB-AC88-F54BC4501539}
1.3.6.1.2.1.2.2.1.2.17 (OctetString): isatap.hsd1.il.comcast.net.
1.3.6.1.2.1.2.2.1.2.18 (OctetString): Microsoft 6to4 Adapter
1.3.6.1.2.1.2.2.1.2.19 (OctetString): Microsoft ISATAP Adapter
1.3.6.1.2.1.2.2.1.2.20 (OctetString): WAN Miniport (IPv6)-QoS Packet Scheduler-0000
1.3.6.1.2.1.2.2.1.2.21 (OctetString): WAN Miniport (IP)-QoS Packet Scheduler-0000
1.3.6.1.2.1.2.2.1.2.22 (OctetString): WAN Miniport (Network Monitor)-QoS Packet Scheduler-0000
1.3.6.1.2.1.2.2.1.2.23 (OctetString): Realtek RTL8101E Family PCI-E FE NIC-QoS Packet Scheduler-0000
1.3.6.1.2.1.2.2.1.2.24 (OctetString): Intel(R) PRO/Wireless 3945ABG Network Connection-QoS [..]
1.3.6.1.2.1.2.2.1.2.25 (OctetString): Intel(R) PRO/Wireless 3945ABG Network Connection-Native [...]