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perfSONAR Element Identifiers

perfSONAR has a structure identifier for each topological element. The goal of the structure in these elements is to create identifiers that are independent of the location of the element definition, can be easily summarized and can have some basic type checking performed, all while retaining reasonable human readability.

The syntax of these identifiers takes the URN format described in RFC 2141. We're currently using the "ogf:network" urn namespace, but we still need to get the approval for this namespace use.

Every ID begins with the standard header of:

urn:ogf:network:

What follows is a set of name/value fields describing each topological element.

Currently, we have 8 fields defined: domain, node, port, link, path, network and service. These correspond to the elements used in our topology schema. The fields are defined with the identifiers in a hierarchical manner. With the exception of the domain field, the values for each field can be anything, though they must be unique at the level of the hierarchy that they are in, and they should be human readable.

Domain Field

The "domain" field is used in identifiers to describe the administrative domain/subdomain in which a network element is located. The value of the field is a DNS name for the domain/subdomain. Thus, the identifier for the stanford.edu domain might look like:

urn:ogf:network:domain=stanford.edu

Its "slac" subdomain might look like:

urn:ogf:network:domain=slac.stanford.edu

Node Field

The "node" field is used to describe a logical or physical device inside a domain. If a node field exists, it must follow the domain field immediately. A logical value for this field might be the hostname.

The node 'packrat' at Internet2 would have the identifier:

urn:ogf:network:domain=internet2.edu:node=packrat

Port Field

The "port" field can be used to refer logical or physical ports. If the port is logical, then its identifier would depend on whether it is a logical domain port which could be handled by multiple hosts inside the domain, or a logical node port which exists completely in a given node. If it's the former, then the port field will appear immediately after the domain field. Example:

urn:ogf:network:domain=internet2.edu:port=interfaceToGeant

If the interface is a physical one, or a logical one inside a given device, the field will come immediately after the "node" field. Logical value choices would be the interface name on the host (e.g. eth0 or ib0) or the physical name of the port on a router. Examples:

urn:ogf:network:domain=internet2.edu:port=eth0

urn:ogf:network:domain=internet2.edu:port=interfaceToGeant

Link Field

The "link" field can be used to refer to logical or physical undirectional or bidirectional links. If the link is bidirectional or a logical unidirectional link, the link field will come immediately after the domain field. Example:

urn:ogf:network:domain=internet2.edu:link=linkToGeant

If the link is a physical unidirectional link or one side of physical bidirectional link, the link field will come after the 'port' field of the interface that can write that link. Example:

urn:ogf:network:domain=internet2.edu:port=interfaceToGeant:link=linkToGeant

Path Field

The "path" field is used in identifiers for named paths through the network. These would include things like circuits. These named paths can be used by a single domain or be shared across multiple. If a path exists solely for a given domain, it's path field should come immediately after the domain field for the domain it exists in. Example:

urn:ogf:network:domain=internet2.edu:path=OSCARScircuit_3838

The path field can also be the only field in the identifier for a cross-domain named path or a path that exists in a cross-domain context, but happens to only use a single domain. Example:

urn:ogf:network:path=OSCARScircuit_4578

Network Field

The network field is used to describe named element groups inside a domain or named element groups that cross domain boundaries. If the named network exists solely in a given domain, the field should come immediately after the domain field for the domain its in. Example:

urn:ogf:network:domain=internet2.edu:network=patdev

If the grouping crosses domain boundaries or is part of a larger system of cross-domain groups, but happens to only include elements from a single domain, the network field should be the only field in the identifier. Example:

urn:ogf:network:network=slacMonitoringHosts

Service Field

The service field can be used to describe domain or node level services that are offered. These could include things like a web service offered by a domain, a telnet server running on a host or an adaptation service on a specific interface. Where the field exists in these identifiers depends on what level this service exists at.

For a service that is offered by a domain, but not necessarily specific to a given logical or physical device, the service field should be immediately after the domain field containing the domain its in. Example:

urn:ogf:network:domain=internet2.edu:service=IDC

For a service offered on a specific logical or physical node, the service should be immediately after a node field for the logical or physical device running the service. Example:

urn:ogf:network:domain=internet2.edu:node=packrat:service=LS

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