G.805/G.800 applied to NSI
John, See my comments in your G.805/G.800 document. I think that applying G.800 to a NSI network example as you have done here is an interesting exercise. I think the G.800 is a good model that looks well thought through and fits the NSI requirement for a vendor independent network description. G.800 is diagrammatic oriented, as far as I understand the use of this is that it can be used as an object oriented model for creating a database that describes a network in a network management system (TMN principles). But what we really need is a description language that will allow this network model to be exchanged over the NSI interface. I guess the process of creating such a language is the role of the NML group. As far as I can see ITU-T does not have anything like this for G.800 (because it is an object oriented database model only?). Perhaps Freek can comment on this in tomorrow's call. Guy ------------------------------------------------------------------------------------------------------------------ Guy Roberts, Ph.D Network Engineering & Planning DANTE - www.dante.net<http://www.dante.net/> Tel: +44 (0)1223 371 316 City House, 126-130 Hills Road Cambridge, CB2 1PQ, UK ------------------------------------------------------------------------------------------------------------------
Hello, I agree that G.800 is a very valuable input towards describing computer networks. However, reading through the document and the G.800 standard, I'm somewhat confused about the difference between Points and Ports. Also, I'm not entirely convinced that the authors of the G.800 are really sure on this either. Unfortunately, there is no real definition in the G.800 standard describing the relation between the Point and Port. The only thing that comes close is in the diagramatic conventions: A Point is defined as two Ports connected by a Link, all within a Subnetwork. Then they make a distinction between Access Point, Forwarding Point, Forwarding End Point and Link Point, wich are all conveniently denoted by the same symbol. What confuses me is Figure 8. According to their own diagramatic conventions, they are showing Points within Subnetworks. I assume that this is an error and that they meant to use open circles there, thus Ports. However, later on in Table 1 on Page 19 the authors seem to define that all relations are between Points, for example Adaptation is between Forwarding Points, not Ports. And to make it even more confusing there's this paragraph on page 13:
An "access relationship" transport entity is created when a forwarding function is configured in a layer network. The ingress access ports and egress access ports of the forwarding relationship are identified together with any policy related to these ports. An access relationship cannot be partitioned. The access relationship may be established either before or after the termination is bound to an adaptation, i.e., it may be bounded by access ports or access points or a combination.
This seems to imply you can somehow mix Points and Ports. The definition of a Link Point seems to be pretty clear, there are two paragraphs describing that: The definition of Access Group:
An access group is a group of co-located termination functions. It is bounded by a link port that contains the individual FwEPts and the set of individual access ports of each of the termination functions. When the link port is bound to a subnetwork or link, it forms a link point.
And the following page contains:
The internal structure of this [transport] plane can be further described by partitioning the largest subnetwork into smaller subnetworks (points of flexibility) and the links that interconnect them. The binding between a link and a subnetwork results in a link point. (This is not directly between Port and Point, but Links are defined to be between two Ports.)
Reading this, I believe that a Link Point consists of two Ports, i.e. the connector on the cable and the physical port on the device. However, I'm completely in the dark about the meanings of Forwarding (End) Points and Access Points. Jeroen.
Hello Jeroen, Jeroen van der Ham wrote:
Then they make a distinction between Access Point, Forwarding Point, Forwarding End Point and Link Point, wich are all conveniently denoted by the same symbol.
I think they are different as the acronyms are part of the 'symbol'.
However, later on in Table 1 on Page 19 the authors seem to define that all relations are between Points, for example Adaptation is between Forwarding Points, not Ports.
Perhaps this bags to try to communicate with the author(s)? In general I like the document so it looks worth to find out these issues. Freek used it in his Thesis so perhaps he also has some view;-) All the best, Victor -- The HEAnet National Networking Conference 2009 – 12&13 November Registration is now open: http://www.heanet.ie/conferences/2009/ Victor Reijs, Network Development Manager HEAnet Limited, Ireland's Education and Research Network 1st Floor, 5 George's Dock, IFSC, Dublin 1 Registered in Ireland, no 275301 tel: +353-1-660 9040 fax: +353-1-660 3666 web: http://www.heanet.ie/
On Aug 4, 2009, at 3:21 PM, Victor Reijs wrote:
Hello Jeroen,
Jeroen van der Ham wrote:
However, later on in Table 1 on Page 19 the authors seem to define that all relations are between Points, for example Adaptation is between Forwarding Points, not Ports.
Perhaps this bags to try to communicate with the author(s)? In general I like the document so it looks worth to find out these issues. Freek used it in his Thesis so perhaps he also has some view;-)
Anyone know how to contact an author?
All the best,
Victor
participants (4)
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Guy Roberts -
Jeroen van der Ham -
John Vollbrecht -
Victor Reijs