I can't figure out SNMP

mikeybinec

As I start delving into subjects really really deep before I take ICND2, I'm a little confused about snmp.. one of my books sez snmp and netflow compliment each other. So I downloaded a couple of net mon programs like prtg, spiceworks, etc. When I configure
the routers with snmp-server commun LAN rw, I'm not seeing how this program transfers information to a defined host.. In Netflow, you can set an export destination. But how does snmp export it's info? I can't seem to find the correct config so I can see snmp at work. Am I making sense?

Thanks

docrice

SNMP is two-fold: 1) the network management system (the SNMP poller) reaches out to the network device over UDP 161, and 2) the network device can be configured to send "traps" which are just notification messages back to the network management system over UDP 162. SNMPv1 and v2c are relatively simply to configure, but insecure protocols and should be avoided these days.

SNMPv3 is the way to go, but a bit more complicated:

ip access-list standard mysnmpacl
permit host
deny any log
exit

snmp-server location MyCity
snmp-server contact netadmin@mycompany.com
snmp-server group somereadonlyaccount v3 priv read yaddayadda-mib-2
snmp-server group somereadonlyaccount v3 priv context yaddayadda-context-01 read yaddayadda-mib-2
snmp-server view yaddayadda-mib-2 mib-2 included
snmp-server user mynmsusername somereadonlyaccount v3 auth sha LONG-AUTH-PASSWORD priv aes 128 LONG-PRIV-PASSWORD access mysnmpacl

For NetFlow export, you need to first determine if your router or L3 switch supports it. The commands are slightly different depending on device model and which version of NetFlow your flow collector supports (these days it's generally NetFlow v9).

So now the question turns to which SNMP poller and which NetFlow collector you're using.

Mike-Mike

I have Network+, CCNA, and CCNA Security. However in prep for a recent interview I was going back and studying the WGU Skillport for Network+ and they had a very good explanation of SNMP.

Hondabuff

Solarwinds is probably the best NMS out there. Just setup your RW/RO community strings, SNMP server IP and what traps to forward. I just forward everything to our NMS. You get a full blown dashboard of everything you can imagine. When one of my routers go down, It will email the NOC and go into linkdown on our main page. It will tell you what time it went down and has 90 day history of bandwidth, latency, syslog messages, running config/startup config. You can monitor just about everything. If a fan fails or temp spikes It can send out alerts.