anima Y. Li
Internet-Draft Y. Zhou
Intended status: Informational L. Shen
Expires: April 22, 2022 Huawei Technologies
October 19, 2021
Requirement and a Reference Model of L2 ACP based ANI
draft-yizhou-anima-l2-acp-based-ani-00
Abstract
This document discusses the scenarios, requirements and a reference
model of ANI (Autonomic Networking Infrastructure) to be constructed
in a layer 2 network using L2 Autonomic Control Plane (ACP) and the
related functions. It expands the applicability of ANI to L2 network
and maintains the same infrastructure.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Scenarios requiring L2 ACP functions in ANI . . . . . . . . . 2
3. Requirements for L2 ACP and related functions in ANI . . . . 4
4. Reference Model of L2 ACP based Autonomic Node . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
[RFC8993] defines a generic set of functions of Autonomic Network
Infrastructure (ANI). It contains addressing and naming of autonomic
nodes, discovery, negotiation and synchronization functions,
distribution of information, reporting, feedback loops, and routing
inside the Autonomic Control Plane (ACP) [RFC8994]. The Autonomic
Service Agent (ASA) is the atomic entity of an autonomic function and
is instantiated on autonomic nodes. They use the services and data
structures of the underlying ANI via the API exposed. When ASAs
communicate with each other, they should use the Generic Autonomic
Signaling Protocol (GRASP) [RFC8990]. GRASP runs over a secure
substrate that is isolated from regular data plane traffic which is
known as Autonomic Control Plane (ACP).
Though the design concept of ANI is generic, the methods for
constructing an ACP and routing in ACP [RFC8994], discovery of
adjacent system [RFC8990] and interaction of GRASP message are all at
the network layer. This document discusses the scenarios and
requirements of a layer 2 (L2) ACP as an instance of a Generalized
ACP to implement part of ANI functions in L2 network. And it shows a
reference model to construct such L2 ACP and the related functions.
2. Scenarios requiring L2 ACP functions in ANI
Current ACP implementation in ANI uses IPv6 link-local address based
ACP tunnel, RPL as routing protocol in ACP and GRASP DULL to discover
the adjacent node. It is appropriate when the managed network is a
large campus, a multi-site network or a carrier network. However
there are some cases which require L2 ACP functions in ANI. The L2
ACP is used in such cases that the managed network is a reletively
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small layer 2 network where the network nodes have no L3 physical
interfaces and the network manager would like to use and verify the
L2 topology and reachability first for some management purpose.
+-------+
+--|core |--+
| +-------+ | core switch
| |
| |
| |
| |
+-------+ +-------+
| agg 1 |---- | agg 2 | L2 aggregation switch
+-------+ /+-------+
| \ / | \
| \ / | \
| \ / | \
| \ / | \
| \ | \
+-------+ / \ +-------+ +-------+
| acc 1 |/ \| acc 2 | | acc 3 | L2 access switch
+-------+ +-------+ +-------+
| |
| |
| |
| |
+-------+ +-------+
| AP 1 | | AP 2 | wifi access point
+-------+ +-------+
Figure 1: L2 Campus Network
In SOHO or SMB case, the network is not large and the network nodes
have less resource. They are pure layer 2 nodes or nodes to be
enrolled as layer 2 first to form the initial simple topology for
cabling verification. In this case, autonomic network management
with the layer 2 network nodes is required. Figure 1 shows a typical
example of layer 2 network.
For small branch, the number of hosts is usually less than 200, and
the number of WiFi AP and access switches are both less than 10. Two
layers of core and access switch topology is the most common
structure. For a small campus, the number of hosts is usually less
than 2000. Three layer structure, core, aggregation and access
switch topology with some redundancy, might be used. The number of
access switches and WiFi APs are in the order of dozens. The total
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number of network nodes, including switches and APs, is usually less
than 200.
It is sometimes required to firstly form a local area network
disconnected from the Internet. A laptop or mobile phone connected
to a specific node, usually the top level gateway as the core switch
shown in Figure 1, can be used by the network manager to visualize
and verify the topology.
3. Requirements for L2 ACP and related functions in ANI
The generic basic functions of ANI are required for L2 network to be
compliant with the high level autonomic network and node structure.
The assumptions and requirements include,
1. IP addresses of the node and its interface may not be available
upfront.
2. L2 ACP construction can be based on L2 available information and/
or mechanisms, such as MAC address, VLAN or physical port
information. It should not rely on the IP addresses of the
interface.
3. Adjacent node discovery should be carried as L2 frame. When
GRASP DULL is used, it should function without network layer
multicast.
4. It is desired to reuse GRASP messages as much as possible. GRASP
messages should be able to be carried by L2 transport substrate.
5. L2 ACP module should provide API to the upper layer to allow ASA
to invoke L2 based functions.
6. Physical connectivity and topology information should be able to
be collected via L2 ACP for verification.
7. Routing in L2 ACP should support L2 loop-free logical topology
creation.
8. Minimal manual configuration is required. However, L2 ACP can
assume some management VLAN ID is pre-configured and with a
password or encryption key if necessary for security concern.
9. Re-use of the existing well-known multicast MAC addresses is
desired.
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4. Reference Model of L2 ACP based Autonomic Node
Figure 2 shows a reference model when L2 ACP and the related function
is present in ANI.
+-------+ +-------+
| ASA 1 | | ASA 2 |
+-------+ +-------+
^ ^
| |
- - - - - - - - - - - - - - -
API Invoke (L2/L3)
- - - - - - - - - - - - - - -
| |
| |
---------------------------------------------------------------
| Autonomic Networking Infrastructure|
v v
+----------------------------------------------------------+
| Basic ANI functions |
| - Data strcutures |
| - Discovery, negotiation and synchronization functions |
| - Information and Intent Distribution |
| - ... |
+----------------------------------------------------------+
+---------+ +----------------------------------------------+
| | |L2 ACP |
| | |- Neighbour Discovery with L2 GRASP DULL |
| L3 ACP | |- Addressing and reachability |
| | |- Topology collection and loop-free creation |
| | |- GRASP with L2 extension in L2 ACP |
+---------+ +----------------------------------------------+
---------------------------------------------------------------
OS Functions
---------------------------------------------------------------
Figure 2: Model of an Autonomic Node with L2ACP
The conceptual API should allow the ASAs to communicate with other
ASAs by invoking a set of L2 transport based functions in the
underlying ANI. The semantics of data models expressed by the
invoked L2 APIs are expected to be consistent as much as possible
with the L3 API with the similar functions.
Generally L2 ACP provides the similar functions as L3 ACP without
requiring the L3 address and reachability as the transport substrate.
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The DULL instance of GRASP is used to discover neighbours. It uses
the IPv6 link-local multicast address. In layer 2 network, L2 GRASP
DULL is expected to be sent without the requiring L3 addresses. One
of the possible way is to extend L2 control plane protocol to carry
GRASP information. Link Layer Discovery Protocol (LLDP) defined by
IEEE 802.1 can be a candidate of such a protocol as it is able to
discover L2 neighbour nodes and the related L2 information such as
the physical port information and VLAN IDs.
RPL is suggested as a routing protocol used in L3 ACP [RFC8994].
Routing is mostly used for L3 network. RPL is not directly
applicable to run in L2 ACP. Therefore similar functions of topology
collection and loop-free topology creation is required for L2 ACP.
L2 ACP should have its own addressing and L2 reachability scheme to
securely reach L2 autonomic node.
5. Security Considerations
[Editor's notes: It is not completed. Further discussions are
needed.]
The network leverages the L2 ACP and the related functions are
usually small to medium size network in a single or very closed
physical locations. Therefore physical security to prevent access by
unauthorized persons can be used to protect against interlopers and
eavesdroppers.
6. IANA Considerations
No IANA action is required for this document so far. More
consideration will be required for future normative specification of
extensions of GRASP, LLDP and/or other protocols.
7. References
7.1. Normative References
[RFC8990] Bormann, C., Carpenter, B., Ed., and B. Liu, Ed., "GeneRic
Autonomic Signaling Protocol (GRASP)", RFC 8990,
DOI 10.17487/RFC8990, May 2021,
<https://www.rfc-editor.org/info/rfc8990>.
[RFC8993] Behringer, M., Ed., Carpenter, B., Eckert, T., Ciavaglia,
L., and J. Nobre, "A Reference Model for Autonomic
Networking", RFC 8993, DOI 10.17487/RFC8993, May 2021,
<https://www.rfc-editor.org/info/rfc8993>.
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7.2. Informative References
[RFC8994] Eckert, T., Ed., Behringer, M., Ed., and S. Bjarnason, "An
Autonomic Control Plane (ACP)", RFC 8994,
DOI 10.17487/RFC8994, May 2021,
<https://www.rfc-editor.org/info/rfc8994>.
Acknowledgements
TBD
Authors' Addresses
Yizhou Li
Huawei Technologies
Email: liyizhou@huawei.com
Yujing Zhou
Huawei Technologies
Email: zhouyujing3@huawei.com
Li Shen
Huawei Technologies
Email: kevin.shenli@huawei.com
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