[mrtg] Re: SNMP and Cisco ... Oh the Fun a newbie can have.

Hart, Kevin KHart at helixtechnology.com
Wed Sep 1 15:06:20 MEST 2004


We are definitely running MLS and we definitely can get the switchport
(layer 2) counters with SNMP.
Of course measuring VLAN traffic on an MSFC is another matter altogether
which requires Netflow tools.

Moses,
If you want to look at accurate real time counters (for a short term reality
check) use something like STG. MRTG samples at five
minute intervals and a lot of traffic spikes are hidden. STG samples about
every second. At least with this tool you could confirm how
much traffic is happening in between the samples. Not that this is a
replacement for MRTG but just
another tool to give more information. You can dowload it here:

http://leonidvm.chat.ru/

Where did you get the figure for MaxBytes? Was this from Configmaker?
I would use the value below for Gigabit interfaces

MaxBytes[10.4.0.4_107]: 125000000

Remember that this value is in bytes not bits and MRTG will scale the graphs
accordingly. 
Also you might want to consider not using the interface numbers returned by
Cfgmaker.
Sooner or later the interface index will change and you'll have to change
the entire config.
The ifref=name option on cfgmaker is the better way to go...something like
the following.

cfgmaker --ifref=name public at ip address > mrtg.cfg

If you want to change the existing config, just run the "sh port ifindex" on
the 6500 to figure out
what port index numbers like 107 equate to for a port name such as #6/1. 

Here is an example config, not quite as fancy as yours below but it works:

Target[10.0.1.5_6_1]: #6/1:community at 10.0.1.5:::::2
SetEnv[10.0.1.5_6_1]: MRTG_INT_IP="" MRTG_INT_DESCR=""
MaxBytes[10.0.1.5_6_1]: 125000000
Title[10.0.1.5_6_1]: Gigabibt ethernet 6/1 to Some Machine
PageTop[10.0.1.5_6_1]: <H1>Gigabibt ethernet 6/1 to Some Machine </H1>
 <TABLE>
   <TR><TD>System:</TD>     <TD>MCC_6509_1 in </TD></TR>
   <TR><TD>Maintainer:</TD> <TD></TD></TR>
   <TR><TD>Description:</TD><TD>  </TD></TR>
   <TR><TD>ifType:</TD>     <TD>Gigabit Ethernet (6)</TD></TR>
   <TR><TD>ifName:</TD>     <TD>6/1</TD></TR>
   <TR><TD>Port Name:</TD>  <TD>Some Machine</TD></TR>
   <TR><TD>Max Speed:</TD>  <TD>125.0 MBytes/s</TD></TR>
 </TABLE>
Options[10.0.1.5_6_1]: bits

Kevin


-----Original Message-----
From: Moses Hernandez [mailto:moses_hernandez at hotmail.com]
Sent: Tuesday, August 31, 2004 3:25 PM
To: Grossman, Benjamin
Cc: Eric_Mailing_List at rednarb.com; mrtg at list.ee.ethz.ch
Subject: [mrtg] Re: SNMP and Cisco ... Oh the Fun a newbie can have.


RE: [mrtg] Re: SNMP and Cisco ... Oh the Fun a newbie can have.I understand
your thinking on this, but even though we are using MLS I should see more
activity between those ports just because we are transferring pacs images
that can be 50-100MB per case. So I would've imagined that we are using more
of the bandwidth than we are possibly seeing. I am going to try and approach
this differently, instead of monitoring the CoreSwitches i am going to
monitor the IDF's.

Moses.

  ----- Original Message ----- 
  From: Grossman, Benjamin 
  To: 'Moses Hernandez' 
  Cc: Eric_Mailing_List at rednarb.com ; mrtg at list.ee.ethz.ch 
  Sent: Tuesday, August 31, 2004 2:39 PM
  Subject: RE: [mrtg] Re: SNMP and Cisco ... Oh the Fun a newbie can have.


  This is (all to often) the normal case for a Cisco 6500 switch/router. 

  The issue is that, in the most common case, the 6500 is only routing the
first few packets of a given 'conversation'; after that they are switched.
So the traffic counters for the Virtual router Interface are pretty much
useless. 

  The only ways I know around this are to either install some fancy hardware
(Multi-Flow Feature Card?) and matching software; or to disable that part of
the 'switching' function. I seem to recall having some luck with disabling
CEF on that router port---WARNING: this will have a severe negative impact
on router performance! Do not do this lightly.

  -Benjamin 




  -----Original Message----- 
  From: Moses Hernandez [mailto:moses_hernandez at hotmail.com] 
  Sent: Tuesday, August 31, 2004 9:00 AM 
  To: Eric_Mailing_List at rednarb.com; mrtg at list.ee.ethz.ch 
  Subject: [mrtg] Re: SNMP and Cisco ... Oh the Fun a newbie can have. 



  Hmm actually let me do that. Here is what i have right now on one of my 
  interfaces: 

  ### Interface 107 >> Descr: 'DataCenter 2MDF-SW1' | Name: '3/1' | Ip: '' |

  Eth: '00-0d-28-3f-8b-b8' ### 
  ### The following interface is commented out because: 
  Target[10.4.0.4_107]: 107:c1sc0 at 10.4.0.4:161::::2 
  SetEnv[10.4.0.4_107]: MRTG_INT_IP="" MRTG_INT_DESCR="DataCenter 2MDF-SW1" 
  MaxBytes[10.4.0.4_107]: 1000000000 
  Title[10.4.0.4_107]:  DataCenter 2MDF-SW1  -- MIA_6K_MDF1 
  PageTop[10.4.0.4_107]: <H1> DataCenter 2MDF-SW1  -- MIA_6K_MDF1</H1> 
  Options[10.4.0.4_107]: bits, unknaszero 
  YLegend[10.4.0.4_107]: Port Utilization 
  LegendI[10.4.0.4_107]: In 
  LegendO[10.4.0.4_107]: Out 
  Legend1[10.4.0.4_107]: Inbound Bits 
  Legend2[10.4.0.4_107]: Outbound Bits 
  Legend3[10.4.0.4_107]: INBOUND Max value per interval on graph 
  Legend4[10.4.0.4_107]: OUTBOUND Max value per interval on graph 
  Colours[10.4.0.4_107]: GREEN#00eb0c,BLUE#0000ff,GRAY#AAAAAA,VIOLET#ff00ff 
  WithPeak[10.4.0.4_107]: ymw 
  <TABLE> 
     <TR><TD>System:</TD>     <TD>MIA_6K_MDF1 in Mercy MDF</TD></TR> 
     <TR><TD>Maintainer:</TD> <TD></TD></TR> 
     <TR><TD>Description:</TD><TD>  </TD></TR> 
     <TR><TD>ifType:</TD>     <TD>ethernetCsmacd (6)</TD></TR> 
     <TR><TD>ifName:</TD>     <TD>3/1</TD></TR> 
     <TR><TD>Port Name:</TD>  <TD>DataCenter 2MDF-SW1</TD></TR> 
     <TR><TaD>Max Speed:</TD>  <TD>1000.0 MBytes/s</TD></TR> </TABLE> 

  Interestingly enough when i do a show port 3/1 (this is the CatIOS Side, 
  Hybrid Mode) i do not see any counters that would reflect that. show 
  spantree 3/1 shows forwarding in all of the vlans but the graph at the 
  momment display about 

  Max In  8753.5 kb/s (0.1%)   Average In  3592.3 kb/s (0.0%)   Current In  
  4237.3 kb/s (0.1%) 
  Max Out  1520.6 kb/s (0.0%)   Average Out  1205.6 kb/s (0.0%)   Current
Out  
  1207.2 kb/s (0.0%) 



  is that correct? I mean seems awfully low so what i did was telneted to
the 
  other side and looked at the gigabit uplink. This is what i see for 5 
  minutes 

  5 minute input rate 1238000 bits/sec, 933 packets/sec 
    5 minute output rate 3966000 bits/sec, 978 packets/sec 

  Is there something i am missing maybe? or are these numbers accurate and 
  that switch has little to no traffic maybe? 

  Mind you the biggest traffic generation is between the 2 cores and i've
seen 
  the max 50MB/s with the links being Gigabit. 



  >From: Eric Brander <Eric_Mailing_List at rednarb.com> 
  >To: mrtg at list.ee.ethz.ch 
  >Subject: [mrtg] Re: SNMP and Cisco ... Oh the Fun a newbie can have. 
  >Date: Tue, 31 Aug 2004 10:06:06 -0500 
  >MIME-Version: 1.0 
  >Moses Hernandez wrote: 
  > 
  > > I have started using mrtg on a win32 test box. It has been running 
  > > for 5 days on the core router 6500 router side, two remote connect 
  > > routers and 
  >the 
  > > internet firewall. Today I configured the 6500 gigabit switchports 
  > > to 
  >also 
  > > get snmp info. I have noticed not much traffic above the 640.0 K 
  > > usage, maybe 1.2M. I am using mrtg 2.10.15 and I thought it was a 
  > > versioning 
  >issue 
  > > but noticed some others in the archive had similar issues though no 
  > > resolution. As an aside the low numbers are showing up on my nokia 
  >firewalls 
  > > and the numbers are kind of inconsistance with the bandwidth stats 
  > > from 
  >my 
  > > isp. 



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