Troubleshooting sluggish web browsing issue with IP SLA

Unanswered Question
Nov 7th, 2007

IP SLA is the first thing to come to mind for identifying the trouble point(s) in the LAN space when experiencing sluggish response browsing an external website. I assume a basic "http get" is ok for simulating the web browsing, but what is the best option with IP SLA for identifying where the trouble spot is within the LAN space? Would that be the ICMP Path Echo Operation? If I use a third-party tool that measures web site response, would it be possible to kick off ICMP Path Echo Operation on-demand only when there's an identified slow response by that other tool? Is issuing snmpset to the IP SLA router(s) the only means of doing that?

Is CiscoWorks IPM a frontend performing the same steps in the background as outlined in these examples? Is it performing these configs on the routers only with snmpsets? Is it possible to trigger another IP SLA operation upon the "http get" operation hitting a certain response, via IPM or on the router directly, without the benefit of facilities such as EEM?

http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124tcg/tsla_c/htpaecho.htm

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Joe Clarke Wed, 11/14/2007 - 16:21

This post re-appeared high up in the list, but I thought you said you figured it out. If this is not longer an issue, please mark this as resvoled, so the forum doesn't keep trying to escalate it.

yjdabear Thu, 11/15/2007 - 05:46

The forum software must have a bug or something. I think I've seen this behavior before.

The question is still open.

Joe Clarke Thu, 11/15/2007 - 10:47

The IP SLA HTTP operation is actually pretty robust. Yes, it does a simple HTTP GET by default, but what it does behind the scenes in terms of measurement will show you where your low-hanging fruit lies.

The HTTP operation will break down into three components: resolution of the hostname in the URL, time taken to establish the TCP connection, and time take to download the page. Based on this, you can descide where to focus your optimization or troubleshooting efforts.

If you want to isolate where in the network a slow-down is occurring, consider using the Path Echo operation. While it doesn't use TCP probes like the HTTP operation, it will show you a hop-by-hop picture of the IP latency in your network. It can also give you rough idea of where slow-downs are occurring.

Yes, IPM is a frontend for configuring an monitoring IP SLA Collectors (a Collector is an IP SLA source device, target, and operation). IPM uses SNMP to configure and monitor all of its Collectors, and can even be told to put the Collector config in the device's running configuration.

While IP SLA allows you to trigger another operation on a threshold violation, IPM does not support configuring this currently.

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