2 ms delay on Circuit

Unanswered Question
May 31st, 2007


I have dual 100MB circuits to a production site. Each circuit is connected back to a 3845 router on a gigabit interface. These routers are in turn connected back to 2 core switches 6506E sup720.

When I do a ping test I am getting an average latency of 2ms. The carriers tell me that the delay across the circuit should be <1ms.

I run OSPF across the links and evrything is fine in terms of routing. Its just this delay that seems to be confusing me. The configuation for the interaface is as follows:

interface GigabitEthernet0/1

description BT 100MB Circuit

ip address 192.168.x.x 255.x.x.x

ip nbar protocol-discovery

ip pim sparse-dense-mode

ip route-cache flow

ip cgmp

duplex full

speed 100

media-type rj45

negotiation auto


Is there anything that I can do to troubleshoot the delay?



I have this problem too.
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Richard Burts Thu, 05/31/2007 - 08:30


Maybe I am missing something in your description of the issue. But with delay on the circuit <1ms then it seems that sending the ping request gets 1ms and sending the ping response gets 1ms and the total is 2ms. Is there something that I am missing?

One other comment is that using ping from Cisco to Cisco is not a really good way to get accurate measurement of network performance. Processing and responding to ping is a low priority task in Cisco operating system. You could get a potentially significant portion of the reported ping response time which was just processing time in the Cisco gear.



gavin.mckee Thu, 05/31/2007 - 08:36

Hi Rick,

I am doing the ping tests from both ends on both Windows and Unox machines. We you do a traceroute you see all <1ms until it gets to the 3845 router, when it hits the router you then see the step up to 2ms!!


guruprasadr Thu, 05/31/2007 - 20:50


You can do some test to isolate this delay.

1.Extended Ping between the GigEth Interfaces of both the edge Routers

2. Traceroute between these location to identify the routes it takes

3. Debug the IP Packets during such tests.

Pls Rate if Helps

Best Regards,

Guru Prasad R


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