Hight latency on Cisco Router

Unanswered Question
May 19th, 2008


I have a mayer problem with my Cisco 3825. I have the two onboard Ethern Ports plus two sfp tx 1000 (gi 0/1/0 and gi 0/0/0) and two adsl atm 0/3/0 and atm 0/2/0.

I have an internal network on gi 0/0 and an voip lan on gi 0/0/0.111.

I have a dmz with two /29 Networks assigned to gi 0/1.

On Interface gi 0/1/0 I have a conection to a cisco 1700 Router witch is managed by my ISP and has a /30 network as transport network for the DMZ networks.

I use the Cisco router for two site-2-site vpn.

On the ATM Interfaces I have a Dialer1 and a Dialer0.

One is connected to QSC and the other to T-Online. The transport network is also connected to qsc with a 4Mbit SDSL witch in case is a bundle of 2x2MBit through the cisco 1700.

If I ping the Routers interfaces in the transport network or on di1 or di0 I get pings from 200 to 600.

On the di0 port is now traffic. It just dials in and that's it. All the other lines didn't have mach load ether.

when I ping from the same server from outside to a host inside the dmz I get pings about 16ms.

when I ping the outside server from my internal network via NAT I get 200 to 600ms. (remember that hot can ping at the same time dmz host with 16ms)

While we will use vpn to carry voip traffic that pings are far to hight

I have only 1 ACL active on the transport network to lock down all Ports except for some services (about 25 rules).

There is one source based routing to let the dmz go out through gi 0/1/0 (sdls) the nat is done to di 1.

Any idear why the router is to creapy. The load of the router is arround 6%.

I have this problem too.
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tstanik Fri, 05/23/2008 - 05:58

For prioritizing voice you can configure Low Latency Queing(LLQ). Please find below the URL that has more information and example on configuring LLQ:


Here is the URL for the site-to-site VPN configuration :



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