Hi, Richard: From: [email protected] [mailto:[email protected]] On Behalf Of Y. Richard Yang Sent: Monday, October 28, 2013 4:47 AM To: Qin Wu Cc: [email protected]; IETF ALTO Subject: RE: [alto] ALTO Extension: Defining a Cost Metrics document?
Hi Qin, On Oct 25, 2013 11:14 PM, "Qin Wu" <[email protected]<mailto:[email protected]>> wrote: > > Hi,Richard: > > Thank for bring these examples. > > I see these examples from two perspectives: > > 1. What cost metrics we should define? > > 2. When, where and how to calculate these metrics (i.e., methodology ). > > I think we can not define these cost metrics from scratch, we can not define > all the metrics we think useful. Instead, we should define them mostly based > on standardized work, > > AT&T have a good practice for measuring these metrics. But I believe AT&T > also doing a good job in standardizing these metrics and associated > methodology,e.g., > > in IETF IPPM WG. > > Therefore I think we should try to reuse the existing methodology associated > metrics defined somewhere. It may not be necessary to limit ALTO to metrics only defined by other WGs. In other words, limiting ALTO to the representation layer. But as a first step, this can be fine. I am not very familiar with IPPM. Here is a question. How does IPPM handle parameterized metrics, e.g., 15-min vs 5-min measurement interval of latency? I see two problems: - How does a network expose the parameters available (e.g., a network says I can support 5 or 15 min intervals)? ALTO IRD allows exposures of such capabilities. [Qin]: IPPM defines methodology for each metric. In the methodology, it include parameters like source address, dst address, time to measure this metric. However IPPM don't give default value for interval. IPPM didn't define how to report those metrics. Routing protocol can be extended to report those metrics. However Routing protocol didn't report measurement interval directly in the routing message. Instead, such value of interval can be pre-configured. -How does a client specify the parameter chosen or desired? [Qin]: Is a client referred to "ALTO server" that gathers metrics from Routing protocol, or ALTO client that request information from ALTO server? If it is the former, I think ALTO server has its own local policy to decide how to gather those metrics and in which frequency to gather those metrics. If it is the latter, I think ALTO client only care about which endpoint he can connect and which path he can traverse. He does not need to care about Whether this metric is latest measured or measured one hour ago. He can just assume the metric he get is the latest update. Does IPPM have the mechanisms that ALTO can use? [Qin]: IPPM does define Delay Metric, Packet loss metric, Jitter Metric, bandwidth metrics, see RFC5136, RFC2681, RFC2679,RFC3393,RFC2680. We can consider to use them as a reference when we follow RFC6390 performance template. > > > > Also I believe we are not intending to design ALTO as the whole measurement > system or measurement platform. > > What ALTO server should do is to gather/aggregate/abstract/filter useful > metrics in a standard way and provide them > > to the alto client or use them as filtering to choose appropriate endpoint to > connect. Agree. The measurement infrastructure might collect data at 1 min interval, and ALTO exposes only hourly data to certain clients? It is policy controlled. Richard > > > > Regards! > > -Qin > > From: [email protected]<mailto:[email protected]> > [mailto:[email protected]<mailto:[email protected]>] On Behalf Of Y. > Richard Yang > Sent: Monday, October 21, 2013 9:25 AM > To: Qin Wu > Cc: IETF ALTO; [email protected]<mailto:[email protected]> > Subject: Re: [alto] ALTO Extension: Defining a Cost Metrics document? > > > > Hi all, > > > > Just a thought, some networks already provide public performance metrics, and > ALTO should be able to provide such info in a standard way and cover these > metrics, if we agree: > > > > -AT&T > > - http://ipnetwork.bgtmo.ip.att.net/pws/averages.html > > - http://ipnetwork.bgtmo.ip.att.net/pws/network_delay.html > > shows latency, loss, jitter, reliability, modem success rate > > > > - In particular, the link provides a methodology page > (http://ipnetwork.bgtmo.ip.att.net/pws/glossary.html), which points to a > major challenge in defining the metrics: metrics have parameters (e.g., the > AT&T link specifies 15-min interval for latency), and I assume that ALTO > cannot work with a single interval, but then how do we handle parameters? > > > > - CenturyLink (formerly Qwest): > > - https://kai04.centurylink.com/PtapRpts/Public/BackboneReport.aspx > > shows jitter, latency, pkt delivery rate, availability > > > > ... > > > > And we could think that ALTO could be extended to be used as a standard way > to check on the service outage of an endpoint > (http://customer.comcast.com/help-and-support/cable-tv/outages-in-your-area/), > which may imply performance metrics as well... > > > > Thanks. > > > > Richard > > > > On Mon, Oct 14, 2013 at 2:30 AM, Qin Wu > <[email protected]<mailto:[email protected]>> wrote: > > From: [email protected]<mailto:[email protected]> > [mailto:[email protected]<mailto:[email protected]>] On Behalf Of Y. > Richard Yang > Sent: Monday, October 14, 2013 7:20 AM > To: IETF ALTO > Cc: [email protected]<mailto:[email protected]>; Qin Wu > Subject: [alto] ALTO Extension: Defining a Cost Metrics document? > > > > Dear all, > > > > I am reading up on the documents that define cost metrics. > > > > The motivation is that the base ALTO protocol > (http://www.ietf.org/id/draft-ietf-alto-protocol-20.txt) has defined only one > Cost Metric: 'routingcost': > > > > - Defined the semantics at Sec. 6.1.1.1 of , and then listed it at Table 3. > > > > - Used "hopcount" in examples of Sec. 9.2.3 and 9.2.4, but the semantics of > not formally defined. > > > > Given the aforementioned state of the base protocol, I see good value in that > the WG produces a WG document that defines a relatively complete set of Cost > Metrics. > > > > I particular, I read the following: > > > > - http://tools.ietf.org/html/draft-lee-alto-app-net-info-exchange-02 > > (Sec. 3.4 introduced three metrics: hopcount, latency, pktcost, and cost) > > > > - http://tools.ietf.org/html/draft-wu-alto-json-te-01 > > Defined a set of metrics: in Sec. 4. This work, as stated in the document, > is motivated by > > > > - http://www.ietf.org/id/draft-ietf-ospf-te-metric-extensions-04.txt > > > > During the review of ALTO base protocol, we are suggested to document > performance metrics (cost metrics) per the guideline of > > - RFC 6390 Guidelines for Considering New Performance Metric Development. A. > Clark, B. Claise. October 2011. (Format: TXT=49930 bytes) (Also BCP0170) > (Status: BEST CURRENT PRACTICE) > > > > Here a first question, I have, is whether the authors will produce a "simple" > document, at the upcoming IETF, whose only purpose is to: > > > > define a set of cost metrics, including the nameing, the semantics, ... > following the guideline per RFC 6390, that can benefit the base protocol. > > > > [Qin] This is exactly what I we are doing in draft-wu-alto-json-te. We are > checking if we can give a complete list of cost metrics that are built based > on > > draft-ietf-idr-ls-distribution-03,RFC5305, > draft-wu-idr-te-pm-bgp,draft-ietf-ospf-te-metric-extensions-04, > draft-ietf-isis-te-metric-extensions-01. > > We will further generalize them to firstly have some base metrics that can > applied either to the whole path or any link in the path and then have > > Derived metrics that are link specific. > > > > The update (v-02) will come in a few days. > > > > > > I feel that such a document is focused, and has good value by itself. > > > > The implications of the introducing multiple cost metrics can be explored in > another document, which I will send in another email shortly. > > > > Thanks. > > > > Richard > > > >
_______________________________________________ alto mailing list [email protected] https://www.ietf.org/mailman/listinfo/alto
