Re: [sfc] Figures in draft-quinn-sfc-arch-05
"Jakob Heitz (jheitz)" <jheitz@cisco.com> Fri, 30 May 2014 17:55 UTC
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From: "Jakob Heitz (jheitz)" <jheitz@cisco.com>
To: Eric Gray <eric.gray@ericsson.com>, Linda Dunbar <linda.dunbar@huawei.com>, Lucy yong <lucy.yong@huawei.com>, Joel Halpern <joel.halpern@ericsson.com>, "Paul Quinn (paulq)" <paulq@cisco.com>
Thread-Topic: Figures in draft-quinn-sfc-arch-05
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Date: Fri, 30 May 2014 17:55:00 +0000
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Subject: Re: [sfc] Figures in draft-quinn-sfc-arch-05
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Here is a good example of an RFC with readable diagrams http://www.rfc-editor.org/rfc/rfc1131.pdf How did he upload that? --Jakob From: sfc [mailto:sfc-bounces@ietf.org] On Behalf Of Eric Gray Sent: Friday, May 30, 2014 8:03 AM To: Linda Dunbar; Lucy yong; Jakob Heitz (jheitz); Joel Halpern; Paul Quinn (paulq) Cc: sfc@ietf.org Subject: Re: [sfc] Figures in draft-quinn-sfc-arch-05 Linda, It may be a mathematically correct expression (depending on interpretation of the notation used), but networking is not necessarily (possibly even usually) a mathematical operation. There is nothing "intuitively obvious" in this expression that makes it clear that "load sharing" is taking place between the sets of sf2 and sf4 instances, or how the "or" operation takes place. One literal way to interpret this notation (as a mathematical expression) is that each the functions sf2, sf2' and sf2" are "visited" sequentially and passed on to sf3 as soon as it succeeds in any of the functions. With this interpretation, since the service function performed at each sf2 instance is presumed to be identical, what the expression means is that either the service function will succeed at sf2 (and always skip sf2' and sf2"), or that it will fail at each sf2 instance. An equally legitimate "parallel computing" (not exactly mathematical, but possibly viewed as more closely analogous to networking) interpretation would be that processing passes (on success at sf1) to each of sf2, sf2' and sf2" in parallel and then proceeds to sf3 on success at any of the sf2 instances. None of these interpretations corresponds to "load sharing" - yet all are perfectly legitimate interpretation of your suggested expression/notation. And yet, these are actually more common interpretation of the usage of an "or" operation to computing folks (which many of us are), depending on their specific background in computing. As I said before, I have no objection to the suggested notation you and Lucy proposed - provided that the notation is explained. I am unclear as to what value this usage - and included explanation may have - but this is largely a style issue, and best left up to the draft editors at this point. And, as I also said, there may be others who would prefer not to have too much textual explanation necessary in order to understand a figure. Finally, you must realize that there are a fairly large number of folks who read-over mathematical expressions as if they were written in a foreign language. For this reason, even if it were a perfectly useful/correct mathematical expression, a number of folks would still need a picture. -- Eric From: Linda Dunbar [mailto:linda.dunbar@huawei.com]<mailto:[mailto:linda.dunbar@huawei.com]> Sent: Thursday, May 29, 2014 5:42 PM To: Eric Gray; Lucy yong; Jakob Heitz (jheitz); Joel Halpern; Paul Quinn (paulq) Cc: sfc@ietf.org<mailto:sfc@ietf.org> Subject: RE: Figures in draft-quinn-sfc-arch-05 Importance: High Eric, How about this shorter one? ->{sf1}->{sf2|sf2'|sf2''}->{sf3}->{sf4|sf4'|sf4''}->{sf5}-> The intent is pretty simple: If a service function on a chain has multiple instances, one of the service function's instances is selected to treat packets belonging to the service chain. This is a correct mathematics expression. There is really no need draw all those boxes. Linda From: Eric Gray [mailto:eric.gray@ericsson.com] Sent: Thursday, May 29, 2014 4:23 PM To: Linda Dunbar; Lucy yong; Jakob Heitz (jheitz); Joel Halpern; Paul Quinn (paulq) Cc: sfc@ietf.org<mailto:sfc@ietf.org> Subject: RE: Figures in draft-quinn-sfc-arch-05 Linda, By the way, your proposal for Figure 5 would require a column width of at least 80 characters (more than you are supposed to have in an ID), and the situation would be worse if it were applied to figure 6. For figure 5, you can improve the width slightly by fixing up a few of your arrows, and even more by wrapping the figure. Wrapping might detract from simplicity, however. -- Eric From: Linda Dunbar [mailto:linda.dunbar@huawei.com] Sent: Thursday, May 29, 2014 4:49 PM To: Lucy yong; Eric Gray; Jakob Heitz (jheitz); Joel Halpern; Paul Quinn (paulq) Cc: sfc@ietf.org<mailto:sfc@ietf.org> Subject: RE: Figures in draft-quinn-sfc-arch-05 Importance: High I like the Figures drawn by Lucy. Actually why can't Figure 5 be simplified as enter -->{sf1}-->-{sf2|sf2'|sf2''}->--{sf3}-->-{sf4|sf4'|sf4''}->--{sf5}--> exit ?? Linda From: sfc [mailto:sfc-bounces@ietf.org] On Behalf Of Lucy yong Sent: Thursday, May 29, 2014 1:12 PM To: Eric Gray; Jakob Heitz (jheitz); Joel Halpern; Paul Quinn (paulq) Cc: sfc@ietf.org<mailto:sfc@ietf.org> Subject: Re: [sfc] Figures in draft-quinn-sfc-arch-05 For readability on these figures, propose: Figure 5: +-sf2-+ +-sf4-+ | | | | enter -->sf1-->-sf2->--sf3-->-sf4->--sf5--> exit | | | | +-sf2-+ +-sf4-+ Figure 6: +-sf2-+ +-sf4-+ | | | | enter -->{sf1|sf1'}-->-sf2->--{sf3|sf3'}-->-sf4->--{sf5}--> exit | | | | +-sf2-+ +-sf4-+ lucy From: sfc [mailto:sfc-bounces@ietf.org] On Behalf Of Eric Gray Sent: Thursday, May 29, 2014 12:54 PM To: Jakob Heitz (jheitz); Joel Halpern; Paul Quinn (paulq) Cc: sfc@ietf.org<mailto:sfc@ietf.org> Subject: Re: [sfc] Figures in draft-quinn-sfc-arch-05 HaHa, funny man. :) From: Jakob Heitz (jheitz) [mailto:jheitz@cisco.com] Sent: Thursday, May 29, 2014 1:43 PM To: Eric Gray; Joel Halpern; Paul Quinn (paulq) Cc: sfc@ietf.org<mailto:sfc@ietf.org> Subject: RE: Figures in draft-quinn-sfc-arch-05 Importance: High You could turn the whole picture right by 90 degrees. If you don't like top to bottom instead of left to right, make a note that it's in landscape. --Jakob From: sfc [mailto:sfc-bounces@ietf.org] On Behalf Of Eric Gray Sent: Thursday, May 29, 2014 8:31 AM To: Joel Halpern; Paul Quinn (paulq) Cc: sfc@ietf.org<mailto:sfc@ietf.org> Subject: [sfc] Figures in draft-quinn-sfc-arch-05 Paul/Joel, Pretty sure that Figures 5 and 6 don't actually fit the width expected for an Internet Draft (Figure 5 is more than 80 characters wide and Figure 6 is wider still). Depending on how a reader tries to read the draft, this can turn complicated illustrations into a _real_ fun time. :) Also, I am unsure what the figures are trying to convey with some of "dotted lines" crossing the service functions. If the intent is to show that a service function is a virtual instance hosted by some network device, perhaps this will be better shown in a separate figure and this aspect of Figures 5 and 6 can be eliminated? I would suggest replacing Figure 5 with a figure along the lines of: source +-----+ +-----+ | +-->| sf2 +--+ +-->| sf4 +--+ | | | | | | | | | | +------+--+ +-----+ +-->+-----+--+ +-----+ +->+-----+ | | sf1 | +-----+ | sf3 | +-----+ | sf5 | +->| +----->| sf2 +----->| |----->| sf4 +---->| |-+ | | | | | | | | | | | +------+--+ +-----+ +-->+-----+--+ +-----+ +->+-----+ | | +-----+ | | +-----+ | | +-->| sf2 +--+ +-->| sf4 +--+ +----+ | | | | | +-----+ +-----+ V destination Figure 5: Load Balancing (67 characters?) Similarly, I would suggest replacing Figure 6 with a figure along the lines of: source | +-----+-+ +-----+-+ +---+ +-->| sf2 |-|+ +-->| sf4 |-|+ | +---|-->| | || +------>| | || | +------+|---+ +-----+ |+-->+-----+|---+ +-----+ |+-->+-----+ | | sf1 || +-----+ +--->| sf3 || +-----+ +--->| sf5 | +-->| +|------>| sf2 |+---->| ||------>| sf4 |+---->| |--+ | | || +---->| |-+ | || +---->| |-+ | | | | +------+|-|-+ +-----+ |+-->+-----+|-|-+ +-----+ |+-->+-----+ | | | | | +-----+ || | | | +-----+ || | | +------++ | +-->| sf2 |-|+ +-----++ | +-->| sf4 |-|+ +-----+ | | | sf1' | | +-->| | +--->| sf3'| | +-->| | +--->| sf5'| | +-->| +--+ | +-----+----->| |--+ | +-----+----->| |--+ | | | | | | | | | +------+----+ +-----+----+ +-----+ | | +--------+ | V destination Figure 6: Load Balancing and HA (72 characters?) In both cases, the figure has all the same connection complexity (fixed up in a few places), but seems to be less busy. -- Eric
- [sfc] Figures in draft-quinn-sfc-arch-05 Eric Gray
- Re: [sfc] Figures in draft-quinn-sfc-arch-05 Jakob Heitz (jheitz)
- Re: [sfc] Figures in draft-quinn-sfc-arch-05 Eric Gray
- Re: [sfc] Figures in draft-quinn-sfc-arch-05 Lucy yong
- Re: [sfc] Figures in draft-quinn-sfc-arch-05 Linda Dunbar
- Re: [sfc] Figures in draft-quinn-sfc-arch-05 Eric Gray
- Re: [sfc] Figures in draft-quinn-sfc-arch-05 Eric Gray
- Re: [sfc] Figures in draft-quinn-sfc-arch-05 Linda Dunbar
- Re: [sfc] Figures in draft-quinn-sfc-arch-05 Lucy yong
- Re: [sfc] Figures in draft-quinn-sfc-arch-05 Eric Gray
- Re: [sfc] Figures in draft-quinn-sfc-arch-05 Jakob Heitz (jheitz)
- Re: [sfc] Figures in draft-quinn-sfc-arch-05 Eric Gray
- [sfc] Specifying chains of network functions [Re:… Sevil Mehraghdam
- Re: [sfc] Specifying chains of network functions … Dave Dolson
- Re: [sfc] Specifying chains of network functions … Sevil Mehraghdam