[Nsi-wg] STP lists and path ordering

[John MacAuley]

This one has to do with whether the existing STP list with ordering information is sufficient to understand the path a service should take, or has been computed to take.  I have included the basic schema for reference.

As an example let us use a connection request through three domains (A, B, and C) with source STP A1 and destination STP C2.  Let us assume that the chosen path is A1->A2->B1->B2->C1->C2.  With the existing schema definitions we would get something like this:

{
    sourceSTP=A1
    destSTP=C2
    stpList={ (1,A2), (2,B1), (3,B2), (4,C1) }
}

If I remember correctly, the issue we have was that this model is:
1. There is an assumption that sourceSTP A1 is the edge of the connection, and routing will proceed inside domain A, not immediately to the domain adjacent to STP A1.
2. Assumes because A1 and A2 are in the same domain the connection is routed internally to that domain.
3. Assumes that when two STP are adjacent in the ordered list, but in different domains, that there must be an SDP between the two.  For example, A2 and B1 must be topologically adjacent and share an SDP.

So I guess the question is should we be using SDP here instead of STP?

John.

    <xsd:complexType name="PathType">
        <xsd:sequence>
            <xsd:element name="directionality"  type="tns:DirectionalityType" default="Bidirectional"/>
            <xsd:element name="sourceSTP"       type="tns:ServiceTerminationPointType" />
            <xsd:element name="destSTP"         type="tns:ServiceTerminationPointType" />
            <xsd:element name="stpList"         type="tns:StpListType" minOccurs="0" />
        </xsd:sequence>
    </xsd:complexType>

    <xsd:complexType name="StpListType">
        <xsd:sequence>
            <xsd:element name="stp" type="tns:OrderedServiceTerminationPointType" minOccurs="0" maxOccurs="unbounded" />
        </xsd:sequence>
    </xsd:complexType>

    <xsd:complexType name="OrderedServiceTerminationPointType">
        <xsd:sequence>
            <xsd:element name="stpId" type="tns:StpIdType" />
        </xsd:sequence>
        <xsd:attribute   name="order" type="xsd:int" />
    </xsd:complexType>