Tag Archives | snmp

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VRF-Aware SNMP on Brocade VDX

SNMP was not designed with VRFs in mind. Querying the routing table via SNMP did not take into account the idea of having multiple routing tables. But clearly it’s something people want to do, so some clever engineers figured out how to shoe-horn VRF contexts in. This week a customer asked me how to query […]

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Brocade VDX SNMP Changes

Brocade tightened up some SNMP settings with NOS 6.0.x. This improves security, but it also means that you will need to modify your configuration if you upgrade. If you don’t, SNMP won’t work, and you’ll get errors with BNA/Nagios/Cacti/etc. Here’s the changes, and how to get SNMP working with NOS 6.0.x. NB This applies to […]

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influxdb-logo

Using InfluxDB + Grafana to Display Network Statistics

I loathe MRTG graphs. They were cool in 2000, but now they’re showing their age. We have much better visualisation tools available, and we don’t need to be so aggressive with aggregating old data. I’ve been working with InfluxDB + Grafana recently. Much cooler, much more flexible. Here’s a walk-through on setting up InfluxDB + […]

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Accurate Dependency Mapping – One Day?

Recently I’ve been thinking about Root Cause Analysis (RCA), and how it’s not perfect, but there may be hope for the future. The challenge is that Automated RCA needs an accurate, complete picture of how everything connects together to work well. You need to know all the dependencies between networks, storage, servers, applications, etc. If you […]

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nms_graph

No Alarms May Not Mean No Problems

Network monitoring is often a reactive process. Engineers see an alarm, and take action. Alarms mean someone broke something, and it needs attention. Deal with the alarms, and all will be well. No alarms == Good. But every now and then no alarms means that monitoring is broken. Here’s an example of where this happened, and what […]

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nms_graph

SNMP Counters – Collection Interval Variation

Counter data types are commonly used in SNMP monitoring. They are extremely useful, but there’s a couple of caveats around how to use them. Here’s a couple of issues I’ve come across: What are Counters? From RFC 2578: The Counter32 type represents a non-negative integer which monotonically increases until it reaches a maximum value of […]

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Monitoring IPv6 vs IPv4 Traffic on Juniper SRX

I use a Juniper SRX 110 at home, and my ISP is enlightened enough to offer IPv6 by default to all customers. My devices are dual-stack, and I know that a lot of content is now available via IPv6 and IPv4. I’ve been trying to figure out how to measure the volume of IPv6 traffic, and I […]

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SNMP vs SDN

IOS-XR: Stuck between SNMP and SDN

SNMP may be outdated, and is definitely unloved, but it still serves a purpose. We’re moving to a new world, with new methods and data structures for interrogating and configuring our network devices. This is a Good Thing, but we’re not there yet, and this leaves us stuck in limbo for trying to solve Real […]

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nms_graph

SNMP Community Strings – Don’t Use ‘@’

A quick reminder – do not use the symbol ‘@’ in SNMPv1/2 community strings. I came across this again this week – it causes issues with monitoring some equipment, and should be avoided. Let’s just ignore the massive SNMPv1/v2c security issues for a second. Since people see the community string as a password, it’s common […]

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