4 Replies Latest reply on Sep 24, 2015 12:20 PM by tommygator

    Nagios MRTG reports low bandwidth and high pings at times

    tommygator New Member

      The issue: MRTG shows very low bandwidth on 192.168.xx.1 Adtran routers (Under 1MB) but intermittently we get very high (500 -1000ms) ping times with severe slow downs at the branch endpoints.

       

      We have Netvant 1238/1224 PoE and Adtran 3430 Routers with very basic  configurations.  We have ATT MPLS and Metro-E at 3MB and 10MB respectively at branches in a hub and spoke back to Headquarters 100MB ATT Cisco router

       

      All devices point to the Adtran router (192.168.xx.1) as the gateway which routes all traffic to the ATT routers (192.168.xx.2)  (I know it is an unnecessary hop but we do not have access to the ATT routers and may have wanted backup connectivity at some point in the past).  Both Routers are connected to the primary switch via single 100MB eth port 0/1 (IOW:,  these routers are not directly connected to each other in line)

       

      Some branches have two switches daisy chained on GigE ports. There are 10-40 devices at each branch sending all internet and intranet traffic back to HQ,, Domain Controllers are at each branch.

       

      I have only 1 VLAN set on the switches and all are full 100mb connections (except GigE of Course)  Any ideas of where to start looking for possible bandwidth throttling or cap on traffic flow    Here is a sample switch config:

      !
      !
      hostname "BRANCHNAME"
      enable password md5 encrypted xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
      !
      ip subnet-zero
      ip classless
      ip routing
      !
      event-history on
      logging forwarding on
      no logging console
      logging forwarding priority-level info
      logging forwarding receiver-ip 192.168.XX.XX
      no logging email
      logging email priority-level info
      !
      username "XXXX" password "PPPP"
      !
      banner motd ^
      Welcome to the Jungle ^
      !
      banner login ^
      !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
      STOP! This is a private computer system on a private computer network.
      ALL access is logged and monitored.
      Unauthorized users are not allowed and any attempt to enter the network or
      this system without explicit permission will result in civil and criminal
      liabilities.
      !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
      ^
      !
      !
      !
      !
      !
      !
      !
      !
      !
      !
      !
      vlan 1
        name "Default"
      !
      interface eth 0/1
        no shutdown
      !
      interface eth 0/2
        no shutdown
      !
      interface eth 0/3
        no shutdown
      !
      interface eth 0/4
        no shutdown
      !
      interface eth 0/5
        no shutdown
      !
      interface eth 0/6
        no shutdown
      !
      interface eth 0/7
        no shutdown
      !
      interface eth 0/8
        no shutdown
      !
      interface eth 0/9
        no shutdown
      !
      interface eth 0/10
        no shutdown
      !
      interface eth 0/11
        no shutdown
      !
      interface eth 0/12
        no shutdown
      !
      interface eth 0/13
        no shutdown
      !
      interface eth 0/14
        no shutdown
      !
      interface eth 0/15
        no shutdown
      !
      interface eth 0/16
        no shutdown
      !
      interface eth 0/17
        no shutdown
      !
      interface eth 0/18
        no shutdown
      !
      interface eth 0/19
        no shutdown
      !
      interface eth 0/20
        no shutdown
      !
      interface eth 0/21
        no shutdown
      !
      interface eth 0/22
        no shutdown
      !
      interface eth 0/23
        no shutdown
      !
      interface eth 0/24
        no shutdown
      !
      !
      interface vlan 1
        ip address  192.168.XX.1  255.255.255.0
        no shutdown
      !
      !
      interface t1 1/1
        description XX to YY T1
        tdm-group 1 timeslots 1-24 speed 64
        no shutdown
      !
      interface t1 1/2
        line-length 0
        shutdown
      !
      interface bri 1/1
        shutdown
      !
      interface ppp 1
        ip address  192.168.205.2  255.255.255.255
        no shutdown
        cross-connect 1 t1 1/1 1 ppp 1
      !
      !
      !
      !
      !
      ip route 0.0.0.0 0.0.0.0 ppp 1
      !
      no ip tftp server
      no ip http server
      ip http secure-server
      no ip snmp agent
      no ip ftp agent
      !
      !
      !
      !
      !
      !
      !
      !
      line con 0
        login
        password md5 encrypted xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
        line-timeout 3
      !
      line telnet 0 4
        login
        password md5 encrypted yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
        line-timeout 3
      !
      !
      !
      !
      end


      Thanks for any help,

      Tom

        • Re: Nagios MRTG reports low bandwidth and high pings at times
          Employee

          Tom,

           

          Thanks for posting your question to the forum!

           

          I would start by verifying there are not any errors or duplex mismatches on the physical interfaces of the routers involved. Also, what 2 endpoints is MRTG measuring ping and bandwidth against? Based on the configuration above, it looks like there is a T1 connection set up as the WAN so that would be a bottleneck in itself when coming from a gig-speed switch network.

           

          Please let us know if you have any questions.

           

          Thanks,

          Noor

            • Re: Nagios MRTG reports low bandwidth and high pings at times
              tommygator New Member

              The Interfaces T1 and PPP are remnants of the past on this config.  We have two Routers plugged into the switch.  all are set to Full-Auto - One router is our monitored router at xxx.1 (Adtran Router) and the other is our wan router (ATT-Cisco) at xxx.2 

              We route all packets through our Adtran router and back out through the switch to our ATT router  This way we can monitor traffic in and out of the wan since we do not have access to SNMP or other monitoring of the ATT router.

               

              The slow ping times witnessed are to each these routers plugged into the switch -  I realize the gig speed to wan causes a bottleneck,  but that should only be witnessed on the ATT router that queues the packets for delivery

               

              also, I don't see any reason why the T! and old PPP interfaces are not shutdown in this scenario - Do You?

               

              interface t1 1/1

                description XX to YY T1

                tdm-group 1 timeslots 1-24 speed 64

                no shutdown

               

              interface ppp 1

                ip address  192.168.205.2  255.255.255.255

                no shutdown

                cross-connect 1 t1 1/1 1 ppp 1