Re: [Teas-ns-dt] Proposed text for section "Transport Slice Endpoint"

["Rokui, Reza (Nokia - CA/Ottawa)" <[e-mail]>]

Hi Sergio,

Sorry, I missed your email. See  my responses inline.

Reza



From: Sergio Belotti <[e-mail]>
Date: Wednesday, June 17, 2020 at 5:27 AM
To: Reza Rokui <[e-mail]>om>, "[e-mail]" <[e-mail]>
Cc: Sergio Belotti <[e-mail]>
Subject: RE: [Teas-ns-dt] Proposed text for section "Transport Slice Endpoint"

Hi Reza,
Some comments on line and suggested rewording

Thanks
Sergio

From: Teas-ns-dt <[e-mail]> On Behalf Of Rokui, Reza (Nokia - CA/Ottawa)
Sent: Tuesday, June 16, 2020 8:08 PM
To: [e-mail]
Cc: Rokui, Reza (Nokia - CA/Ottawa) <[e-mail]>
Subject: Re: [Teas-ns-dt] Proposed text for section "Transport Slice Endpoint"

All,

Following is the modified version of the transport slice endpoint section. Please provide your comments.

Cheers,

Reza


4.2.  Transport slice endpoints

   As discussed in section 3, the transport slice consists of a set of connections between multiple endpoints with a specified connectivity type and one or more SLOs associated with it.

   The transport slice endpoints are the logical identifier to identify the head-end and tail-end points of a transport slice and to perform the forwarding of the user traffic. The characteristics of the transport slice endpoints (TSE) are:

   - They are conceptual point of connection of a network function, device or application to the transport slice.
   - They are logical identifier and requested by the customer of transport slice during the creation of the transport slice
SB> I would say “provided” : the customer should know what is the logical identifier from which want to start/terminate his TS right?
[Reza] Agreed. Will be included.

   - They are associated with (hosted by) exactly one application, device, network function (ADN)
   - The cardinality between a TSE and ADN is many:1, i.e. a single device or application can host multiple transport slice endpoints
   -  A TSE is identified by its hosted ADN (its IP address, name , ID etc), TSE unique identifier, TSE unique name and other data. Non-exhaustive list of other data is IP address v4 and v6, VLAN, port, connectivity type (i.e. P2P, P2MP, MP2MP) etc.). TDB to add more

   Note that the concept of the transport slice endpoint is similar to the Link Termination Point (LTP) defined in [draft-ietf-teas-yang-te-topo-18] and access points (AP) defined in [RFC8453] with an important difference.
SB> I clearly see the similarity with AP, but I would delete the relation with LTP since LTP is not a “logical” identifier, is a real termination point of a TE link terminating on a specific node. LTP is mapped to a local or remote link identifier (see RFC 3630). In the VN YANG model, an LTP is the VN-AP related termination point on the TE node . So it is clearly distinguished by AP and specific VN-AP.
[Reza] You are right about LTP. But, the text for transport slice endpoints is not saying whether AP or LTP is logical or physical. The main point of my text is that Transport Slice Endpoints are different.

The main difference between them is that both LTP and AP are associated to traffic engineering (TE) whereas TSE is not. In other words. the AP (See section 2.1 RFC8453) is a common identifier for the TE link a logical identifier shared between customer and provider to identify an access link and LTP is a conceptual point of connection of a TE node to one of the TE links, terminated by the TE node (see section 3.5 draft-ietf-teas-yang-te-topo-18) whereas TSE is a logical head-end and tail-end of the transports slice connections. The TE characteristic of the network might be taken into consideration during the realization of a transport slice.

   There is another type of the endpoints called "Transport Slice Realization endpoints (TSRE)". These endpoints are allocated  and assigned by the network controller during the realization of a transport slice and are technology-specific, i.e. they depends on the network technology which is used during the transport slice realization. They are identified by a hosted node and some associated data. A non-exhaustive list of devices containing TSRE are routers, switches, firewalls, WAN, application acceleration, Deep Packet Inspection (DPI), server load balancers, NAT44 [RFC3022], NAT64 [RFC6146], HTTP header enrichment functions, and TCP optimizers

4.2.1.  Connectivity patterns within Transport Slice

   The transport slices are a set of connections among the set of  endpoints.  These connections can be point to point (P2P), point to
   multipoint (P2MP), multi-point to point (MP2P), or multi-point to  multi-point (MP2MP) based on the connectivity type requested by the customer.