Tx and Rx Load Too High

Unanswered Question
May 8th, 2009
User Badges:

Hi All,

I am facing a strange problem in my network. For WAN connectivity we are using 64 Kbps LL connected via serial link, the Tx and Rx load in the Serial interface is increasing drastically, even when there is no traffic flow or minimum traffic flow.

The strange thing is if I shut the Fast Ethernet port in the remote end, the Tx and Rx load in the near end serial interface increases suddenly and reaches up to txload 227/255 and rxload 227/255.

Need ur help in resolving the issue at the earliest.

Thanks in Advance.


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
John Blakley Fri, 05/08/2009 - 10:43
User Badges:
  • Purple, 4500 points or more


You may want to enable netflow on the interface ingress and egress to see what's coming in and out of the network.



vasu.vk85 Fri, 05/08/2009 - 11:25
User Badges:


Thanks for ur reply. Can u explain me in detail, what steps I need to take?


John Blakley Fri, 05/08/2009 - 11:36
User Badges:
  • Purple, 4500 points or more


You can try:

Router(config)#ip flow-top-talkers

Router(config-flow-top-talkers)#top 10

Router(config-flow-top-talkers)#sort-by bytes


Router(config)#int g0/1

Router(config-if)#ip route-cache flow

To show the top talkers:

Router# sh ip flow top-talkers

The top traffic generators will be listed at the top.



vasu.vk85 Fri, 05/08/2009 - 11:46
User Badges:


I didn't see this message earlier. I will try this and share the output.

Thanks for ur help.


vasu.vk85 Fri, 05/08/2009 - 11:49
User Badges:


In my router, ip flow-top-talkers is not supported. Any other option?


Brent Rockburn Fri, 05/08/2009 - 11:25
User Badges:

Can we see a "show int" on the serial and a "sh run int" on that as well?

vasu.vk85 Fri, 05/08/2009 - 11:37
User Badges:


I am pasting the Show run int and show int output.

sh run int se1/0:30


interface Serial1/0:30

description xxxx

ip address x.x.x.x x.x.x.x

encapsulation ppp

ppp authentication chap


sh int se1/0:30

Serial1/0:30 is up, line protocol is up

Hardware is M32X with CSU/DSU

Description: ***

Internet address is x.x.x.x/30

MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,

reliability 255/255, txload 227/255, rxload 227/255

Encapsulation PPP, LCP Open

Listen: CDPCP

Open: IPCP, loopback not set

Keepalive set (10 sec)

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 02:35:07

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 392

Queueing strategy: weighted fair

Output queue: 0/1000/64/392 (size/max total/threshold/drops)

Conversations 0/187/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 48 kilobits/sec

5 minute input rate 57000 bits/sec, 107 packets/sec

5 minute output rate 57000 bits/sec, 107 packets/sec

142081 packets input, 8931367 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

141756 packets output, 8874954 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

Timeslot(s) Used:31, Transmitter delay is 0 flags

John Blakley Fri, 05/08/2009 - 11:40
User Badges:
  • Purple, 4500 points or more


Something is using 57k of your 64k line. The netflow will help.


vasu.vk85 Fri, 05/08/2009 - 11:43
User Badges:


ip flow-top-talkers is not supported in my router. Any alternate command?


vasu.vk85 Fri, 05/08/2009 - 12:07
User Badges:


Router model is 3845 and the IOS version is c3845-advipservicesk9-mz.124-15.XZ.bin


John Blakley Fri, 05/08/2009 - 12:43
User Badges:
  • Purple, 4500 points or more


I'll take your word for it. I would've thought netflow would've been in that image, but I don't have that particular image to test.

Looks like you'd need:

12.4(25) c3845-advipservicesk9-mz.124-25.bin

to be able to support netflow.

Other than having a sniffer, I can't think of any other way you can configure anything on the router that would show you the traffic.



This Discussion