c# 利用snmp中OID值获取VALUE值

using System;
using System.Collections.Generic;
using System.Text;
using SnmpSharpNet;
using System.Net;

namespace BankProject
{
    class SnmpUtil
    {
        private SimpleSnmp snmp = null;

        private Dictionary<Oid, AsnType> result = null;

        public SnmpUtil()
        {
            
        }

        public SnmpUtil(string host, string community)
        {
            host = host == "" ? ReadyAppConfig.ConfigManager("snmp_host") : host;
            community = community == "" ? ReadyAppConfig.ConfigManager("snmp_community") : community;
            snmp = new SimpleSnmp(host, community);
        }

        private bool isValid()
        {
            bool bol = true;
            if (!snmp.Valid)
            {
                bol = false;
                return bol;
            }
            return bol;
        }

        private Dictionary<Oid,AsnType> SnmpClient(string oid)
        {
            result = snmp.Walk(SnmpVersion.Ver1, oid);
            return result;
        }

        public List<object> excuteInit(SnmpDao oid)
        {
            List<object> list = null;
            if(isValid())
            {
                Dictionary<Oid,AsnType> result=SnmpClient(oid.Oid);
                if(result!=null)
                {
                    list = new List<object>();
                    foreach (KeyValuePair<Oid, AsnType> entry in result)
                    {
                        string ss = string.Format("{0}|{1}|{2}", entry.Key.ToString(), SnmpConstants.GetTypeName(entry.Value.Type),
                          entry.Value.ToString());
                        list.Add(ss);
                    }
                }
            }
            return list;
        }


    }
}

 网上下载SNMPSHARPNET第三方DLL文件，引入工程中，根据他现有的API进行测试

以下是我的DAO文件，用于存放OID值 

using System;
using System.Collections.Generic;
using System.Text;

namespace BankProject
{
    class SnmpDao
    {
        private string oid;

        public string Oid
        {
            get { return oid; }
            set { oid = value; }
        }
        
    }
}

 建一个WINFORM，测试一下

private void snmpCLientGet() 
        {
            SimpleSnmp snmp = new SimpleSnmp(host, community);
            
            if (!snmp.Valid)
            {
                Console.WriteLine("SNMP agent host name/ip address is invalid.");
                return;
            }
            //Dictionary<Oid, AsnType> result = snmp.Walk(SnmpVersion.Ver1, "1.3.6.1.2.1.25.2.3.1.4.2");
            
            Dictionary<Oid, AsnType> result = snmp.Get(SnmpVersion.Ver1, new string[] { ".1.3.6.1.2.1.25.3.2.1.3.1" });
            if (result == null)
            {
                Console.WriteLine("No results received.");
                return;
            }

            foreach (KeyValuePair<Oid, AsnType> kvp in result)
            {
                string s=string.Format("{0}= {1}: {2}", kvp.Key.ToString(), SnmpConstants.GetTypeName(kvp.Value.Type), kvp.Value.ToString());

                richTextBox1.Text =richTextBox1.Text+"\n"+s;
            }
            
        }

        private void snmpClientWalk()
        {
            SimpleSnmp snmp = new SimpleSnmp(host, community);
            Dictionary<Oid, AsnType> result = snmp.Walk(SnmpVersion.Ver1, ".1.3.6.1.2.1.25.3.5.1.1");
            if (result == null)
            {
                Console.WriteLine("Request failed.");
            }
            else
            {
                foreach (KeyValuePair<Oid, AsnType> entry in result)
                {
                    string ss = string.Format("{0} = {1}: {2}", entry.Key.ToString(), SnmpConstants.GetTypeName(entry.Value.Type),
                      entry.Value.ToString());
                    richTextBox1.Text = richTextBox1.Text + "\n" + ss;
                }
            }
        }

        private void runInfo_Click(object sender, EventArgs e)
        {

            //string func = System.Reflection.MethodBase.GetCurrentMethod().Name+"()";
            
            //this.panel3.Controls.Add(new TestControl());
            //snmpClientWalk();
            //snmpCLientGet();
            
            SnmpDao sd = new SnmpDao();
            sd.Oid = ".1.3.6.1.2.1.25.3.5.1.1";
            SnmpUtil snmp = new SnmpUtil("","");
            List<object> list=snmp.excuteInit(sd);
            foreach(string s in list)
            {
                richTextBox1.Text = richTextBox1.Text + "\n" + s;
            }
            
        }

        private void snmpSetPdu()
        {
            string community = "private";
            SimpleSnmp snmp = new SimpleSnmp(host, community);
            List<Vb> vblist = new List<Vb>();
            Oid setOid = new Oid("");
            OctetString setValue = new OctetString("");
            vblist.Add(new Vb(setOid,setValue));
            Dictionary<Oid, AsnType> result = snmp.Set(SnmpVersion.Ver1, vblist.ToArray());
            if(result==null)
            {
                Console.WriteLine("发送失败");
            }
            else 
            {
                Console.WriteLine("发送成功");
            }
        }

 经测试成功获取

但为什么有的OID只能用GET获取到，有的OID只能用WALK获取到，没有理解，哪位大神可以给俺解释下，谢谢了