3

I'm facing this problem from last 10-15 days. One of my Locations is connected thru MPLS (Router IP 10.34.7.2) (See image for setup). The users are complaining of slow or no connectivity. on checking the gateway router the interface is showing no traffic.

router#sh int e0
Ethernet0 is up, line protocol is up
  Hardware is PQUICC Ethernet, address is 000e.841e.1317 (bia 000e.841e.1317)
  Internet address is 10.34.7.1/16
  MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 10Mb/s
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters 22:58:10
  Input queue: 1/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  30 second input rate 1000 bits/sec, 1 packets/sec
  30 second output rate 1000 bits/sec, 1 packets/sec
     123988 packets input, 19333333 bytes, 0 no buffer
     Received 78771 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 input packets with dribble condition detected
     67690 packets output, 13952579 bytes, 0 underruns
     18 output errors, 1967 collisions, 1 interface resets
     0 babbles, 0 late collision, 336 deferred
     18 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out
Router#
interface Ethernet0 
ip address 10.34.7.1 255.255.0.0 
load-interval 30 
no cdp enable 
! 
interface Serial0 
no ip address 
shutdown 
fair-queue 
no cdp enable 
! ip classless 
ip route 0.0.0.0 0.0.0.0 10.34.7.2 
ip route 10.0.0.0 255.0.0.0 10.34.7.2 
ip route 142.147.0.0 255.255.0.0 10.34.7.2 
ip route 172.16.15.0 255.255.255.224 10.34.7.2

Pleae help me out in this. I've tried reloading router. and the switch too. When I' ping from router to HO with size defined. I get traffic on interface.

Location Connectivity

  • 1
    Do a traceroute from the end host to your HQ. Does the traffic follow the router or the ISP? Also, please include the router configuration. – Ron Trunk Sep 26 '17 at 11:25
  • Traced from user its going towards gateway router Router config is as below interface Ethernet0 ip address 10.34.7.1 255.255.0.0 load-interval 30 no cdp enable ! interface Serial0 no ip address shutdown fair-queue no cdp enable ! ip classless ip route 0.0.0.0 0.0.0.0 10.34.7.2 ip route 10.0.0.0 255.0.0.0 10.34.7.2 ip route 142.147.0.0 255.255.0.0 10.34.7.2 ip route 172.16.15.0 255.255.255.224 10.34.7.2 ! – Ajay Bohra Sep 27 '17 at 6:49
  • Your configuration looks wrong. Where is 10.34.7.2? Is that the MPLS router? Edit your original question and use the "pre-formatted text" option. – Ron Trunk Sep 27 '17 at 14:02
  • Yes, the MPLS router LAN Interface is 10.34.7.2. I've edited the original question too. Sorry for the goofup. – Ajay Bohra Sep 28 '17 at 7:13
  • 1
    I would switch your device's default gateway to the MPLS router. You need to re-think what you're trying to accomplish here. All traffic gets forwarded to the MPLS router- so what is the purpose of the gateway router? Are you trying to have a backup path? – Ron Trunk Sep 29 '17 at 11:23
3

You don't define a default gateway on a different subnet. So according to your picture, if the computers are configured with a 10.34.10/16 range, then their gateway should be within this range (e.g. 10.34.10.1). You can't just put any number you want and expect the computers to find their way their by themselves. It would be like you asking me how to fly to Moscow and me telling you to fly to London first, when you don't don't know how to fly to London either.

Some network protocols allow a computer to discover it's own gateway if no other correct choice is configured. That is likely what is happening with the traffic finding it's way to the MPLS router instead. They probably broadcasted for a pathway out of their subnet and the MPLS router was the only thing to respond.

My advice is to put a secondary IP address with the range of 10.34.10.x/16 and then set your default gateway to that. That is of course if you can't simply re-address that interface to 10.34.10.x entirely.

0

You can add ip flow ingress/ip flow egress under the interface (Ethernet0 in your case). This will enable NETFLOW caching of the traffic passing through that link. No worries no risk involved.

After that you can execute show ip cache-flow and you will see all the packets passing through that interface. Most probably the rest of the devices have more specific routing and default gateway is not used at all.

0

I am seconding the notion of stepping back a bit, and reassessing what features you want in play on your flows. Summarize what is happening to packets if they hit .1 at a high level. Break it into big chunks of functionality. Do you need this? Is there other stuff that is supposed to be working on .1, but isn't? Do you have a security business requirement, pushing you to have further edge separation? If this is a whole lot of no, then I would seriously think about just sending your traffic direct to the .2 router. It's already numbered with your all of your clients.

Why are you really sending traffic thru .1? I think that's where you land at the moment.

Hope this helps!

-m

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