Adding delay to a router

Unanswered Question
Jun 26th, 2009
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Thought this one was simple, alas not so far. I have a 2800 router running 12.4 with 2 Gig Interfaces on it. 1 machine on each of the interfaces. You can ping back and fourth and I have about a 0.5msec. I want to increase the delay to simulate WAN delay. So looking thru docs I found the interface delay command. Alas I have tried it and even rebooted router with no luck. Config shown below. The ping delay remains at 0.5msec. With ths below I would expect it to jump up to 60.5msec.


Any ideas:


interface GigabitEthernet0/0

description Engineering Network

ip address 10.2.107.254 255.255.0.0

no ip redirects

no ip unreachables

no ip proxy-arp

ip route-cache flow

ip igmp join-group 224.165.156.168

delay 3000

duplex auto

speed auto

ipv6 address autoconfig

no mop enabled

!

interface GigabitEthernet0/1

description PSH Network

ip address 10.3.0.1 255.255.0.0

no ip redirects

no ip unreachables

no ip proxy-arp

ip route-cache flow

ip igmp join-group 224.165.156.168

delay 3000

duplex auto

speed auto

ipv6 address autoconfig

no mop enabled

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John Blakley Fri, 06/26/2009 - 06:47
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Paul,


This delay command is used for routing protocol calculations and path determination. You could try to ping with larger packets to simulate higher ping times:


ping x.x.x.x size 10000 rep 100


That *might* work. Default is 1500, but you can start with the above and decrease until you start getting replies. It's possible that you could time out with the above because your responding end may drop packets that large.


HTH,


John

paul.houldsworth Fri, 06/26/2009 - 07:10
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Thanks for the responses so far.


What I want to achieve is an increase in end-to-end delay for all packets being routed thru the router. small pings, large pings, UDP data, etc. So while a large ping does add .1msec of delay, it does not change the delay of a 1000 byte ping with a router setting of delay 3000 or no delay.


Changing the interface speed to 10M is not an option. 100M might be, although it would not be ideal. Again however that does not have the desired effect.

John Blakley Fri, 06/26/2009 - 07:14
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What is it your ultimately trying to accomplish? Your *best* option may be shaping if you have access to the other end of the link. You could classify your traffic and then shape it based on your needs.


John

paul.houldsworth Fri, 06/26/2009 - 07:27
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I am trying to simulate end-to-end WAN delay with a single 2800 router than in essence has virtually no delay. I have control over both sides of the router. shaping you say? Will have to look that up as I have no used it before.

jgagznos Fri, 06/26/2009 - 07:39
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Paul,


You need to get a WAN simulator to perform the tests that your after. Besides doing some kind of "funky" QoS configuration (which won't accurately test what you are after), there is no way to do this from the command line.


Take a look at the Shunra WAN simulators. This will allow you to properly inject delay, jitter, and packet loss for testing. BTW - there are other vendors to choose from, this one just comes to mind.


http://www.shunra.com/free-trials.php


HTH,

Joe

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