Nagios MRTG reports low bandwidth and high pings at times

[tommygator]

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

[Anonymous]

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

[tommygator]

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

[Anonymous]

Tom,

I'm a little unsure about the configuration. You mentioned that the T1 and PPP are remnants, but the only route on the posted configuration is using PPP as its default gateway interface. Is there an updated configuration?

Also regarding your question about the T1 and PPP interfaces, if they are not in use, then there is no reason for the interfaces to be enabled.

Let us know if you have any questions.

Thanks,

Noor

[tommygator]

vlan 1

  name "Default"

.

.

.

.

interface vlan 1

  ip address  192.168.XX.1  255.255.255.0

  no shutdown

!

This is the default VLAN pointing to the gateway Adtran Router as the next hop.