Application Analysis of SNMP in Data Network Monitoring

According to IAB, SNMP, A Simple Network Management Protocol, has become very popular and has become an industrial standard for reporting management data based on IP networks. Here, we will focus on two applications of SNMP in Data Network Monitoring: real-time monitoring of network latency, real-time drawing of ATM/FR Circuit traffic and circuit alarms.

I. SNMP Network Management Framework Overview

The SNMP Network Management framework consists of two types of entities: one is the network management site (NMS) that executes the network management application (NMA), and the other is the management agent (MA) network elements (NE) used to execute NMS requests ). The Simple Network Management Protocol (SNMP) is used to transmit management information between the network management site and the Network Element proxy. Its role is 1.

SNMP manager, that is, NMA usually uses the SNMP protocol to manage data from MA requests. SNMP proxy, that is, the Management Information Library MIB on the IP host where the MA manages it, and provides support for this management information library.

From NMS to NE, all SNMP commands only change (set) or check (get) variables. In another direction, from NE to NMS, a small number of unrequested messages (traps) are used to indicate asynchronous events. SNMP avoids complex information exchange, and RFC1157 stipulates that it uses UDP transmission protocol for transmission.

Netsnmp is one of the most widely used SNMP software on the network host. It can be downloaded from many image sites on www.Sunfreeware.com. As NMA software, it can be through the SNMP protocol (SNMPv1 (RFC1155-1157), SNMPv2 (RFC 1901-1908), SNMPv3 (RFC 2571-2574) commands, call the object identifier OID string of the device MIB library and write scripts to extract the device parameter values, such as CPU utilization, memory utilization, Process status, latency, port traffic, and performance parameters.

During network maintenance, sometimes the snmpagent service of important devices on the network is suspended or the access permission of the snmpaccess service of routers and switches is restricted.

Ii. Real-time Monitoring of network latency

After Netsnmp is installed, start the host's snmpd process. It becomes an SNMP entity with a manager, that is, NMS.

Taking a Cisco device as an example, the host 192.168.1.4 monitors the network latency of the Cisco router 192.168.1.1 in real time.

On a Cisco router, configure the snmpserver and the allowed access list to accept the management of snmpmanager. The data displayed is as follows: snmp-serverengineID local 00000009020000089A9E47FF, snmp-server community <8bit/s string name> RW 81, snmp-server community <8bit/s string name> RO 81, snmp-server enable traps, snmp-server host 192.168.1.4 <one of the aforementioned 8bit/s strings> snmp, snmp-server trap-source loopback 0, access-list 81 permit 192.168.1.4. SNMP monitors network latency in real time.

On NMS (192.168.1.4), the variable of the NE (192.168.1.1) vro is set through the SNMP protocol to obtain the latency from vroa A (192.168.1.1) to vrob B (192.168.1.2) remoteping. NMS uses the SNMP command change (snmpset) to set the extended ping variable from vroa A to vrob B, including the number of packets, package size, and timeout time. Through the SNMP check (snmpwalk ), get the returned latency result. The data is shown as follows: snmpset-v1-cprivate 192.168.1.1. 1.3.6.1.4.1.9.9.16.1.1.1.16. 331 integer 6 (damage the previous setting), snmpset-v 1-c private 192.168.1.1.1.3.6.1.4.1.9.16.1.1.1.16.331 integer 5 (re-create), snmpset-v 1-c segment "GSR12012" (set CiscoPingEntryOwner ), snmpset-v 1-c private 192.168.1.1. 1.3.6.1.4.1.9.16.1.1.1.2.331 integer 1 (set the Protocol to IP), snmpset-v 1-c private 192.168.1.1. 1.3.6.1.4. 1.9.9.16.1.1.1.3.331x"C0 A8 1 2" (Set destination 192.168.1.2), snmpset-v 1-c private 192.168.1.1. 1.3.6.1.4.1.9.16.1.1.1.6.331 integer 1000 (timeout setting), snmpset-v 1-c private 192.168.1.1. 1.3.6.1.4.1.9.16.1.1.1.4.331 integer 10 (set the number of packets), snmpset-v 1-c private 192.168.1.1. 1.3.6.1.4.1.9.16.1.1.1.5.331 integer 111 (set package size), snmpset-v 1-c private 192.168.1.1.1.3.6.1.4.1.9.9.16.1.1.1.16.331 integer 1 (activate to start executing command action), snmpwa Lk-v 1-c private 192.168.1.1 1.3.6.1.4.1.9.16.1.1.1.12.331 (the returned latency is 1 ms), SNMPv2-SMI: enterprises.9.9.16.1.1.1.12.331 = INTEGER: 1, we write the script, the host can remotely monitor the Cisco router 192.168.1.1.

3. Real-time drawing of ATM/FR Circuit traffic and circuit alarms

Taking Nortel's ATM device as an example, Passport15K/7 K/160 supports VR as snmpagent, NMS accesses the Passport private mib Library (nortel-atmCoreV1.mib) of snmpagent through snmp protocol ), obtain the running or configuration status of the ATM/FR circuit. Real-time drawing of ATM/FR Circuit traffic and circuit alarm 3 is shown.

(1) set VR on the Passport Switch

First, you need to set the virtual router (VR) function of the Passport Switch, so that Passport will act as an snmpagent and respond to the management of SNMP from NMS. After the configuration file is activated, the Passport device, as the snmpagent, accepts the SNMP command request from the nms host a. B. c. d.

(2) SNMP monitoring of Passport switch circuit performance and running status

For example, it monitors the traffic and operation alarms of the circuit connected to the first port (155M port) of the PassportA switch. The case of monitoring is 10. If the ATMVCC circuit is set up on the port, the number of ATM cells sent to Txcell and received to Rxcell can be obtained, that is, the circuit traffic performance. You can also remotely monitor the running status of a circuit through SNMP. Finally, we can write a script. When the circuit status is abnormal, an audible and visual alarm window is displayed, which can be detected in time.

(3) drawing PVC performance flow curve

Based on the circuit performance value obtained by SNMP detection, we use mrtg and other plotting programs to plot the PVC performance flow curve. Display Results of circuit performance monitoring and operation status monitoring.

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