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OETF #5: OCranet family of protocols: NNR (Network to Network Routing)

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The following document is a DRAFT. Any information here may be revised at any time, and suggestions are more than welcome.

Rev. #2017010401 (0.1.1)


This draft defines the NNR (Network to Network Routing) protocol as part of the OCranet family of protocols.  This document outlines how dynamic routing holds networks together in an NNR enabled OCranet network, how signalling is performed to control these networks, and the format of addressing used. This protocol is NOT the base protocol for OCranet networksand REQUIRES the support of specifications detailed in OETF #4; OCR (Ocranet Relay) protocol.


The specifications detailed in OETF #4 only provide a means of cell forwarding for data networks and a robust topology. In the majority of cases it is not intended to be a stand-alone protocol. In a network of this type without any further support, only static routing can be achieved, requiring the manual configuration of connections along a path in a more permanent like manner.

OETF #4 specifically and generously reserves a feature allowing us to control such a network beyond the boundries of its specification and is described in detail under section "Switches", sub-section "Services" in OETF #4. The specifications detailed in this document are built upon this feature, allowing a network to dynamically configure itself given little configuration by introducing 3 concepts called SIGNALLING, DYNAMIC ROUTING, and NODE ADDRESSING.


Signalling is the concept of communicating with a network independent of other connections to receive information from, provide information to, or configure networks, usually in a pasive manner. with NNR, signalling becomes the heart of how an OCranet operates. All signalling in an NNR enabled network occurs on VPI 0, VCI 4. All signals are represented using 8 bit identifiers in a 1 byte header immediately following the VPI and VCI fields in an OCR cell.

List of signal names and identifiers

  • HELLO (0x01)
    Used by the active LOOP COORDINATOR to announce information about the network to newcomers. The information provided is as follows:
    • (8 bits) The revision of the NNR protocol supported by the network (Currently 0).
    • (128 bits) The Link Local address of the LOOP COORDINATOR (This provides the 16 bit Link Local prefix for local scope autoconfiguration)(48 bits) A 32 bit Network identifier and 16 bit Subnet identifier, if either is applicable (For global scope autoconfiguration)
  • WHOIS (0x02)
    Sent by anyone to request if a particular address is in use. This can be an address of any type within the scope of the NNR addressing format [SEE BELOW]. If there is no response within 10 seconds of transmitting the WHOIS signal, then the address is considered up for grabs by the node which original sent the signal. The WHOIS signal is comprised as follows:
    • (128 bits) The address being queried
  • DEIFY (0x03) (Implementation currently optional)
    When no HELLO message has been received by the LOOP COORDINATOR for a given time, It is possible that the LOOP COORDINATOR has failed or disconnected for some reason. In this event, each switch with the same Link Local prefix count the entries in their routing tables for each virtual path, including their temporary cached entries and broadcasts a DEFIY signal on the loop. Though important for reliability, due to the complexities of this operation its implementation is currently optional. The DEIFY signal is comprised as follows:
    • (128 bits) The link local address of the node they wish to become the new LOOP COORDINATOR
  • INUSE (0x04)
    Broadcast message sent by a node witnessing a WHOIS broadcast with their Link Local address to inform the sender that the address is currently in use and active. The INUSE signal is comprised as follows:
    • (128 bits) The address being queried in the WHOIS signal
  • DIALOUT (0x05)(Forward recursive) unicast message sent to the LOOP COORDINATOR to request to build a circuit to the specified global scope address. The DIALOUT signal is comprised as follows
    • (128 bits) The global scope address of the end node to reach
    • (16 bits) A tag number passed back the LINE signal upon successful circuit construction informing the previous-hop / initiating node which connection is ready. This     number can be anything, but should be unique within a short time frame at minimum. This number should be cached and changed at each hop as a security measure to prevent switches from becoming confused during circuit construction.
    • (30 bytes) A host-dependent (Not covered in this document) data payload containing any information the end host needs to set up a connection.
  • ACK (0x06)
    Unicast sent by any node acknowledging a signal from another node. This should be sent after any unicast message to prevent nodes from repeating themselves when signal reliability is necessary. The ACK signal is comprised as follows:
    • (8 bits) The signal identifier being acknowledged.
  • HUP (0x07)
    (Unidirectional/Multidirectional recursive) unicast message sent to the next-hop and/or previous-hop switch indicating to tear down / hang up the active circuit. This causes a recursive ripple effect that automatically tears down a connection. Any nodes in between that have not received the message should eventually time out and initiate an HUP signal themselves if applicable to fully dissassemble the circuit and prevent zombified links. If an HUP signal is not initiated at an endpoint node, then two HUP signals should be produced if applicable; One for the next-hop, and one for the previous hop. For security purposes, an HUP signal MUST ONLY be listened to if it arrives via the VPI & VCI pair it is associated with / forwards to. An HUP signal is comprised as follows:
    • (8 bits) The Virtual Path Identifier in the direction of the teardown
    • (16 bits) The Virtual Channel Identifier in the direction of the teardown
  • LINE (0x08)
    (Reverse recursive) unicast message initiated from the end node providing all information the previous-hop needs to forward messages in a circuit to the next-hop toward the end node. The LINE signal is comprised as follows:
    • (16 bits) The tag specified during the DIALOUT signal
    • (16 bits) The VCI of the next-hop
    • (8 bits) The VPI of the next-hop

NNR uses a 128 bit address format that contains the following information:

  • (16 bits) Address type
  • (16 bits) Address parameters
  • (32 bits) Network identifier
  • (16 bits) Subnet identifier
  • (48 bits) Host identifier

A complete NNR address is represented in the following way:


Where TTTT is the address type, PPPP is the address parameters, NNNNNNNN is the network identifier, SSSS is the subnet identifier, and HHHHHHHHHHHH is the host identifier.

Address types
Current, only two address types are supported. These are Link Local (0x0000), and Link Global (Address type 0x9001).

  • Link Local addresses are unique within a loop and its next-door neighboring networks. The 16 bit parameters field in this case is called the "Local scope prefix" and provides a virtual barrier between networks on the same or adjacent loops. All nodes in the same local network share the same local scope prefix, but a switch bordering multiple networks may have more than one local scope prefix, and thus more than one link local address; One for local network group. Link local addresses are used solely for communicating within a local network group and can not be routed accross networks. A node with only a link local address has the added security of being globally invisible and unreachable without more complex routing infrastructure which is outside the scope of this document.
  • Link Global addresses are unique for each network cluster (And MUST be unique within the entire OCranet scope). These addresses are used for communicating to nodes in neighboring or distant network loops.

Shorthand formatting of addresses

The subnet portion of global scope addresses is required to be present but may optionally used for routing [SEE SUBNETTING]. Likewise, the network AND subnet portions of a link local address are required but never used. For this reason, it is acceptable and RECOMMENDED to use the shorthand (double colon) operator when representing addresses for human readability. The double colon MUST only be used once in an address, and its position is dependent on the address type. A couple examples are provided below:

The Link Local address 9001:0000:37f:0000:a8f35779fe4b     can be shortened to this: 9001:0000:37f::a8f35779fe4b
The Link Global address 0000:5f:00000000:0000:a8f35779fe4b can be shortened to this: 0000:5f::a8f35779fe4b

Dynamic Routing

In order for signals to operate, processes that fit in the category of dyanmic routing are necessary. These processes are as follows:

New node joins a network loop

Host NEWHOST is attached to a network loop. The procedure is as follows:

  1. NEWHOST waits for 20 seconds and listens for a HELLO signal or DEIFY signal.
        - If no signal is received, NEWHOST assigns itself a Local Scope prefix. This may be preconfigured or generated randomly. Use precaution when generating randomly to ensure           that neighboring networks do not share the same prefix. It is much easier to just assign it manually when creating a new network loop for the first time.
        - If a HELLO signal is received, NEWHOST assigns itself the Local Scope Prefix of the LOOP COORDINATOR.
        - If a DEIFY signal is recieved, NEWHOST waits another 20 seconds and resumes from step 1.
  2. NEWHOST uses a UUID (It is RECOMMENDED to use the UUID of the OC network card in use if applicable) to generate a Link Local address using its Local Scope Prefix.
  3. NEWHOST sends a WHOIS containing the Link Local address it generated and awaits for an INUSE signal for 10 seconds.
        - If NEWHOST receives an INUSE signal with the Link Local address it generated, a new 48 bit host identifier must be generated. After this is done, resume to step 2.
        - If NEWHOST does not receive an INUSE signal with the Link Local address it generated within 10 seconds, it assigns itself that Link Local address.
  4. NEWHOST may optionally configure itself a Link Global address following steps 2 through 3 but instead using Link Global addressing.
  5. In the event that NEWHOST is a switch bordering another network and an existing LOOP COORDINATOR is available, NEWHOST sends a NEIGH signal containing a route to the network it binds to the LOOP COORDINATOR.



This document may be a stub; It provides the majority of specifications for the NNR protocol but may be missing some specific features and will be updated within the near future.

Edited by *S3
Dynamic Routing features.
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