Network SLA

Chris Meidinger cmeidinger at
Sat Mar 7 11:26:45 UTC 2009


On 07.03.2009, at 12:12, Saqib Ilyas wrote:

> I must thank everyone who has answered my queries. Just a couple more
> short questions.
> For instance, if one is using MRTG, and wants to check if we can meet
> a 1 Mbps end-to-end throughput between a couple of customer sites, I
> believe you would need to use some traffic generator tools, because
> MRTG merely imports counters from routers and plots them. Is that
> correct?

Yes, if you want to do a test bandwidth, iperf should probably be your  
first stop.

> We've heard of the BRIX active measurement tool in replies to my
> earlier email. Also, I've found Cisco IP SLA that also sends traffic
> into the service provider network and measures performance. How many
> people really use IP SLA feature?

I know a lot of people that use IPSLA. Remember, that you set it up  
between two routers or higher-end switches and it constantly tests  
that connection. However, IPSLA is the wrong tool for a one-off test  
of whether you can push a Mbps from site A to site B, because you need  
to saturate the link to do that test. IPSLA is great for monitoring  
things like jitter.



> Thanks and best regards
> On Mon, Feb 23, 2009 at 1:19 PM, Zartash Uzmi <zartash at>  
> wrote:
>> As I gather, there is a mix of answers, ranging from "building the  
>> resources
>> according to requirements and HOPE for the best" to "use of arguably
>> sophisticated tools and perhaps sharing the results with the legal
>> department".
>> I would be particularly interested in hearing the service providers'
>> viewpoint on the following situation.
>> Consider a service provider with MPLS deployed within its own  
>> network.
>> (A) When the SP enters into a relation with the customer, does the SP
>> establish new MPLS paths based on customer demands (this is perhaps  
>> similar
>> to "building" based on requirements as pointed out by David)? If yes,
>> between what sites/POPs? I assume the answer may be different  
>> depending upon
>> a single-site customer or a customer with multiple sites.
>> (B) For entering into the relationship for providing X units of  
>> bandwidth
>> (to another site of same customer or to the Tier-1 backbone), does  
>> the SP
>> use any wisdom (in addition to MRTG and the likes)? If so, what  
>> scientific
>> parameters are kept in mind?
>> (C) How does the customer figure out that a promise for X units of  
>> bandwidth
>> is maintained by the SP? I believe customers may install some  
>> measuring
>> tools but is that really the case in practice?
>> Thanks,
>> Zartash
>> On Fri, Feb 20, 2009 at 1:16 AM, Stefan <netfortius at> wrote:
>>> Saqib Ilyas wrote:
>>>> Greetings
>>>> I am curious to know about any tools/techniques that a service  
>>>> provider
>>>> uses
>>>> to assess an SLA before signing it. That is to say, how does an
>>>> administrator know if he/she can meet what he is promising. Is it  
>>>> based on
>>>> experience? Are there commonly used tools for this?
>>>> Thanks and best regards
>>> Not necessarily as a direct answer (I am pretty sure there'll be  
>>> others on
>>> this list giving details in the area of specific tools and  
>>> standards), but I
>>> think this may be a question (especially considering your end result
>>> concern: *signing the SLA!) equally applicable to your legal  
>>> department. In
>>> the environment we live, nowadays, the SLA could (should?!? ...
>>> unfortunately) be "refined" and (at the other end - i.e. receiving)
>>> "interpreted" by the lawyers, with possibly equal effects (mostly  
>>> financial
>>> and as overall impact on the business) as the tools we (the  
>>> technical
>>> people) would be using to measure latency, uptime, bandwidth,  
>>> jitter, etc...
>>> Stefan
> -- 
> Muhammad Saqib Ilyas
> PhD Student, Computer Science and Engineering
> Lahore University of Management Sciences

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