DSCP Settings for Host up down and other polling

Anything that you think should be in Cacti.

Moderators: Moderators, Developers

Post Reply
Author
Message
Lazybones
Posts: 40
Joined: Wed Aug 23, 2006 9:47 am

DSCP Settings for Host up down and other polling

#1 Post by Lazybones » Sun Aug 08, 2010 12:20 am

I am rolling out QoS queues on my network and had a few thoughts about monitoring.. Now I could just set a higher priority for all traffic from my Cacti box however I think a more find grain approach in the app would be very useful.

- DSCP setting for ICMP / TCP / UDP host up down poll
- DSCP setting for general SNMP polls
- DSCP settings for Advanced Ping graph, and allow multiple DSCP level graphs per host.

Why this would be useful?

I started to notice that one of my sites had lots of blank graphs right after hitting 100% throughput.. However doing some manual pings I could hit it but with a latency of between 900 and 1300 ms.. Much higher than the cacti default timeout of 400-500.. So I upped my timeout to compensate however it got me thinking that after I upgrade that site to QoS I should set the priority of my monitoring traffic..

I was thinking that host up down detection might be worth prioritizing but graphing might not.. Also I might want to measure how well my QoS is working by measuring latency with different DSCP tag levels at the same time.

I know the poller is being worked on a lot right now.. Maybe QoS /DSCP should be a consideration.

User avatar
TheWitness
Developer
Posts: 14804
Joined: Tue May 14, 2002 5:08 pm
Location: MI, USA
Contact:

#2 Post by TheWitness » Sun Aug 08, 2010 10:31 am

Please provide a bit more background. This is not something that I am familiar with. A couple of research links would be helpful.

TheWitness
True understanding begins only when we realize how little we truly understand...

Life is an adventure, let yours begin with Cacti!

Author of MacTrack, Boost, CLog, SpikeKill, Platform RTM, DSStats, maintainer of Spine, lot's of unpublished work and most of Cacti's bugs.
_________________
Official Cacti Documentation
GitHub Repository with Supported Plugins
Central Plugin Repository
Central Templates Repository


I'm still out there people. Getting excited for Cacti 1.2. I think it will be a great release.

Lazybones
Posts: 40
Joined: Wed Aug 23, 2006 9:47 am

#3 Post by Lazybones » Sun Aug 08, 2010 12:29 pm

DSCP is an attribute of a packet that helps routers / switches / firewalls determine the priority of processing the packet. For example real time voip may need to be delivered before someones bulk FTP download. Also when a line is full it helps the router determine what to drop first.

Google / wikipidia should return more detailed information.

User avatar
Howie
Cacti Guru User
Posts: 5330
Joined: Thu Sep 16, 2004 5:53 am
Location: United Kingdom
Contact:

#4 Post by Howie » Sun Aug 08, 2010 12:38 pm

I always thought that the theory was that management traffic got priority, so that that you can get into that remote router to find out what is going on when the pipe is full...

I don't see what the benefit would be of having different DSCP for ping vs snmp - then you could end up in situations where the poller thinks the host is up (ping) but then makes the congestion worse by firing off a load of snmp requests that will be discarded.

Being able to send requests marked with different codepoints for measurement is interesting though. I think it depends a lot on the underlying SNMP library supporting it, which I don't think net-snmp does. However if you have Cisco devices, you might want to look at the IP SLA features in IOS, which I think can change DSCP/TOS on it's probes, and Cacti can graph it's results.
Weathermap 0.98 is out! & QuickTree 1.0. Superlinks is over there now (and built-in to Cacti 1.x).
Some Other Cacti tweaks, including strip-graphs, icons and snmp/netflow stuff.
(Let me know if you have UK DevOps or Network Ops opportunities, too!)

Lazybones
Posts: 40
Joined: Wed Aug 23, 2006 9:47 am

#5 Post by Lazybones » Sun Aug 08, 2010 12:46 pm

I am aware of the ip sla on cisco gear. My ISP manages part of our mpls and reports using it, however I use a variety of other equipment on my side.

snmp traffic would be easy enough to re classify on my firewalls however I would really like to graph the performance of my ef, af, and untagged traffic as they should have different latancy, jitter and loss stats. As it is all pings from cacti end up as untagged.

User avatar
TheWitness
Developer
Posts: 14804
Joined: Tue May 14, 2002 5:08 pm
Location: MI, USA
Contact:

#6 Post by TheWitness » Sun Aug 08, 2010 3:04 pm

Use snmp ping then.
True understanding begins only when we realize how little we truly understand...

Life is an adventure, let yours begin with Cacti!

Author of MacTrack, Boost, CLog, SpikeKill, Platform RTM, DSStats, maintainer of Spine, lot's of unpublished work and most of Cacti's bugs.
_________________
Official Cacti Documentation
GitHub Repository with Supported Plugins
Central Plugin Repository
Central Templates Repository


I'm still out there people. Getting excited for Cacti 1.2. I think it will be a great release.

Lazybones
Posts: 40
Joined: Wed Aug 23, 2006 9:47 am

#7 Post by Lazybones » Sun Aug 08, 2010 6:43 pm

TheWitness wrote:Use snmp ping then.
If I classify at the router it is an all or nothing thing..

If I want to monitor my 3 classes of service at once I would have to generate packets tagged for each of the queues such as ef, af41 and standard no tag, and graph them at the same time.. This will tell me if one of the queues are full and degrading.. Also I have different SLAs with my provider for each class of traffic... I want my own monitoring to ensure that those SLAs are being met as their monitoring portal seems unreliable and clunky.

crlshn
Posts: 3
Joined: Mon May 10, 2010 2:40 pm

Re: DSCP Settings for Host up down and other polling

#8 Post by crlshn » Mon Aug 27, 2012 9:25 am

the best idea I found was to implement IP SLA in the cisco Routers and Graph Jitter (for example)
[url]http://forums.cacti.net/about19542.html[url]
[url]http://cisco.com/go/ipsla

you may also use iptables to mark the packets or even the router to remark the packet, but you can only mark 1 flow and the stats may not represent what you are looking for.


PD/sorry for my bad english

Lazybones
Posts: 40
Joined: Wed Aug 23, 2006 9:47 am

Re: DSCP Settings for Host up down and other polling

#9 Post by Lazybones » Thu Aug 30, 2012 11:31 pm

IP SLA only works if you have Cisco ISR routers on each end... If you by chance have ASAs or other vendor gear you can't use the feature.

User avatar
Howie
Cacti Guru User
Posts: 5330
Joined: Thu Sep 16, 2004 5:53 am
Location: United Kingdom
Contact:

Re: DSCP Settings for Host up down and other polling

#10 Post by Howie » Fri Sep 07, 2012 4:35 am

Juniper have an equivalent feature in JunOS (don't remember what it's called, but it exists...)
Weathermap 0.98 is out! & QuickTree 1.0. Superlinks is over there now (and built-in to Cacti 1.x).
Some Other Cacti tweaks, including strip-graphs, icons and snmp/netflow stuff.
(Let me know if you have UK DevOps or Network Ops opportunities, too!)

Post Reply