Internet DRAFT - draft-li-casm-address-pool-management-architecture
draft-li-casm-address-pool-management-architecture
Network Working Group C. Li
Internet-Draft C. Xie
Intended status: Informational China Telecom
Expires: November 5, 2017 R. Kumar
R. Lohiya
Juniper Networks
J. Bi
Tsinghua University
W. Xu
Huawei Technologies
May 4, 2017
Coordinated Address Space Management architecture
draft-li-casm-address-pool-management-architecture-00
Abstract
This document describes an architecture for the IP address space
management. It includes architectural concepts and components used
in the CASM (Coordinated Address Space Management), with a focus on
those interfaces to be standardized in the IETF.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on November 5, 2017.
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Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. CASM Reference architecture . . . . . . . . . . . . . . . . . 3
4. CASM Functional and Logical Blocks . . . . . . . . . . . . . 5
4.1. CASM Application . . . . . . . . . . . . . . . . . . . . 5
4.2. CASM Coordinator . . . . . . . . . . . . . . . . . . . . 5
4.3. CASM Device . . . . . . . . . . . . . . . . . . . . . . . 6
5. CASM Interface and operation . . . . . . . . . . . . . . . . 7
5.1. CASM App-facing Interface . . . . . . . . . . . . . . . . 7
5.1.1. Functional requirements . . . . . . . . . . . . . . . 7
5.1.2. General operational . . . . . . . . . . . . . . . . . 8
5.1.3. Interface modeling requirements . . . . . . . . . . . 8
5.2. CASM device-facing Interface . . . . . . . . . . . . . . 8
5.2.1. Functional requirements . . . . . . . . . . . . . . . 8
5.2.2. Interface modeling requirements . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1. Normative References . . . . . . . . . . . . . . . . . . 15
8.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
The address space management is an integral part of any network
management solution. The network architectures are rapidly changing
with the migration toward private and public clouds. At the same
time, application architectures are also evolving with a shift toward
micro-services and multi-tiered approach.
There is a pressing need to define a new address management system
which can meet these diverse set of requirements. Such a system must
be built with well-defined interfaces so users can easily migrate
from one vendor to another without rewriting their network management
systems.
This document defines a reference architecture that should become the
basis to develop a new address management system. We are calling
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this new system as Centralized Address Space Management (CSAM)
system.
A series of use cases are defined in "Use Case Draft". For example,
Broadband Network Gateway (BNG), which manages a routable IP address
on behalf of each subscriber, should be configured with the IP
address pools allocated to subscribers. However, currently operators
are facing with the address shortage problem, the remaining IPv4
address pools are usually quite scattered, no more than /24 per
address pool in many cases. Therefore, it is complicated to manually
configure the address pools on lots of Broadband Network Gateway
(BNG) for operators. For large scale MAN, the number of BNGs can be
up to over one hundred. Manual configuration on all the BNGs
statically will not only greatly increase the workload, but also
decrease the utilization efficiency of the address pools when the
number of subscribers changes in the future.
Above is one example of use case, there are other devices which may
need to configure address pools as well. In this document, we
propose a mechanism to manage the address pools centrally. In this
way, operators do not need to configure the address pools one by one
manually and it also helps to use the address pools more efficiently.
2. Terminology
The following terms are used in this document:
CASM: Coordinated Address Space Management
IPAM: IP Address Management
DA: A device agent in device, which contact with CASM Coordinator
to manipulate address pool
CASM Coordinator: A management system which has a centralized
database manage the overall address pools and allocate address
pools to the device in the devices.
3. CASM Reference architecture
The figure below shows the reference model for CASM. This figure
covers the various possible scenarios that can exist in a CASM
system.
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+-------------+ +-------------+ +-------------+
| CASM | | CASM | | CASM |
|application 1| |application j| |application n|
+------/------+ +------/------+ +------/------+
| | |
| | |
| | |
| | |
| | |
+-------\---------------------\---------------------\-------+
| Coordinated Address Space Management System (CASM) |
| Coordinator |
| +-------------+ +-------------+ +-------------+ |
| | Pool | | Address | | Address | |
| | Management | | Management | | Database | |
| +-------------+ +-------------+ +-------------+ |
| |
+---.-------------------------.--------------------------.--+
| | |
| | |
| | |
| | |
| | |
+----------\--------+ +---------\---------+ +--------\----------+
| | | | | |
| +-------------+ | | +-------------+ | | +-------------+ |
| | Agent | | | | Agent | | | | Agent | |
| +-------------+ | | +-------------+ | | +-------------+ |
| | | | | |
| +-------------+ | | +-------------+ | | +-------------+ |
| | CASM | | | | CASM | | | | CASM | |
| | Distributor | | | | Distributor | | | | Distributor | |
| +-------------+ | | +-------------+ | | +-------------+ |
| Device 1 | | Device 2 | | Device m |
+-------------------+ +-------------------+ +-------------------+
Figure 1: CASM reference architecture
The overall procedure is as follows:
o Operators will configure remaining address pools centrally in the
Address Pool Management System (APMS). There are multiple address
pools which can be configured centrally. The APMS server will
then divide the address pools into addressing unit (AU) which will
be allocated to the agent in devices by default.
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o The agent will initiate Address Pool request to the APMS. It can
carry its desired size of address pool the request, or just use a
default value. The address pool size in the request is only used
as a hint. The actual size of the address pool is totally
determined by APMS. It will also carry the DA's identification
and the type of address pool.
o APMS looks up the remaining address pool in its local database.
It will then allocate a set of address pools to the DA. Each
address pool has a related lifetime.
o DA receives the AddressPool reply and use them for their purpose.
o If the lifetime of the address pool is going to expire, the DA
should issue an AddressPoolRenew request to extend the
lifetime,including the IPv4, IPv6, Ports, etc.
o The AddressPoolReport module keeps monitoring and reports the
current usage of all current address pools for each transition
mechanism. if it is running out of address pools, it can renew the
AddressPoolRequest for a newly allocated one. It can also release
and recycle an existing address pool if the that address pool has
not been used for a specific and configurable time.
o When the connection of APMS is lost or the APMS needs the status
information of certain applications, the APMS may pre-actively
query the DA for the status information.
4. CASM Functional and Logical Blocks
4.1. CASM Application
CASM Application is a functional entity which usually used to manage,
operate, maintain the CASM Coordinator. For example, operator or
external user can manage the address pool in CASM Coordinator, and
access log, address allocation records, etc.
4.2. CASM Coordinator
Coordinated Address Space Management System (CASM) Coordinator is a
centralized address management coordinator for CASM application to
maintain the overall address pools, addresses, address properties,
etc.
It maintains an address database including the overall address pools
(OAP) and the address pool status (APS). CASM Applications can
maintain its remaining address pools in the OAP. They can also
reserve some address pool for special-purpose usage. The address
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pools status is to reflect the current usage of the address pools for
different devices. CASM Coordinator also has the interface to
maintain the address pools to different devices dynamically.
4.3. CASM Device
A CASM Device is responsible for distribute or allocate address from
local address pools received from CASM Coordinator.
Device agent (DA) is a component in a CASM device through which
contact with CASM Coordinator. It initiates the address pools
allocation requests, passes the address pools to local instances,
report the status of local address pool usage and update the address
pools requests, etc. for some devices, e.g. v6transition, VPN, etc.,
additional routing modules needs to update the routing table
accordingly.
CASM Distributor is another component in a CASM device, DHCP Server
is a typical distributor which can assign IP addresses to client
computer, DHCP protocol is usually used for this assignment. The
address assignment procedure between the CASM Distributor and
computer is out of scope of this draft.
The device determines whether the usage status of the IP address pool
in device is satisfies the condition. The address pool is a sharable
resource, when the resource in device is insufficient or excessive,
the device sends address pools request to the CASM Coordinator, and
receives response with address pools allocated for this device from
CASM COORDINATOR server. Then it can use this address pools for
assignment. In addition, it reports usage status of local address
pool and update the address pools requests, etc.
The typical CASM devices such as BNG, BRAS, CGN, DHCP Server, NAT,
V6Transition, DNS Server, etc., are described in use cases of "draft-
xie-ps-centralized-address-management-02" and "draft-kumar-casm-
problem-and-use-cases-00".
The form of device is diverse, it can be physical or virtualized, and
it can be a box integrated with control plane and user plane, or
separated control plane remote from box and one or more devices share
centralized control plane. In this device form, the control plane
will manage multiple user plane devices. A number of devices that
are subordinate to a control plane will jointly share the address
pools to make the utilization more high.
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5. CASM Interface and operation
5.1. CASM App-facing Interface
5.1.1. Functional requirements
The CASM should support following functionality for it to be adopted
for wide variety of use cases.
5.1.1.1. Address pools
A CASM system should allow ability to manage different kind of
address pools. The following pools should be considered for
implementation; this is not mandatory or exhaustive by any means but
given here as most commonly used in networks. The CASM system should
allow user-defined pools with any address objects.
Unicast address pool:
o Private IPv4 addresses
o Public IPv4 addresses
o IPv6 addresses
o MAC Addresses
Multicast address pool:
o IPv4 address
o IPv6 address
5.1.1.2. Pool management
There should be a rich set of functionality as defined in this
section for operation of a given pool.
Address management:
o Address allocation either as single or block
o Address reservation
o Allocation logic such as mapping schemes or algorithm per pool
o
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General management:
o Pool initializing, resizing, threshold markings for resource
monitoring
o Pool attributes such as used to automatically create DNS record
o Pool priority for searching across different pools
o Pool fragmentation rules, such as how pool can be sub-divided
o Pool lease rules for allocation requests
5.1.2. General operational
The CASM architecture consists of three major distinct entities: CASM
Application, CASM Coordinator and network device with a device Agent.
In order to provide address space and pools resource that CASM
Coordinator can centrally maintaining, there is an interface between
CASM Applications and CASM Coordinator. The CASM Application can
manage the address space and pool in the CASM Coordinator, and the
get address allocation records, logs from CASM Coordinator.
5.1.3. Interface modeling requirements
There are three broad categories for CASM interface definition:
Pool management interface: Interface to external user or applications
such as SDN controller to manage addresses
Log interface: Interface to access log and records such as DHCP, DNS,
NAT Integration interface: Interface to address services such as
DHCP, DNS, NAT
5.2. CASM device-facing Interface
5.2.1. Functional requirements
In order to build a complete address management system, it is
important that CASM should be able to integrate with other address
services. This will provide a complete solution to network operators
without requiring any manual or proprietary workflows.
DHCP server:
o Interface to initialize address pools on DHCP server
o Notification interface whenever an address lease is modified
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o Interface to access address lease records from DHCP server
o Ability to store lease records and play back to DHCP server on
reboot
DNS server:
o Interface to initialize NAT pools
o Interface to access NAT records from NAT device
o Ability to store NAT records and play back to NAT device on reboot
5.2.1.1. General operational
The CASM architecture consists of three major distinct entities: CASM
Application, CASM Coordinator and network device with a device Agent.
In order to provide address pool manipulations between CASM
Coordinator and device, the CASM architecture calls for well-defined
protocols for interfacing between them. For example, legacy protocol
such as radius to compatible with legacy network equipment. In
modern network management system, device acts as NETCONF/RESTCONF
server side. It sends address pool request to the CASM Coordinator
which is protocol client, the centralized CASM Coordinator responses
with allocated address pool, the device receives the response message
and retrieve the allocated address pool information carried in the
response message.
The overall address management procedure is as follows:
o Address Pool Management System (CASM) Coordinator configure
remaining address pools centrally. There are multiple address
pools which can be configured. The CASM Coordinator will then
divide the address pools into addressing unit (AU) which will be
allocated to the agent in devices by default.
o The agent will initiate Address Pool request to the CASM
Coordinator. The device judges whether the address resource used
by the device meet certain conditions, the condition indicates the
use status of the address resource with the device. Then it
generate and issue an Address Pool request in which carried its
desired size of address pool, or just use a default value. The
address pool size in the request is only used as a hint. The
actual size of the address pool is totally determined by CASM
Coordinator. It will also carry the DA's identification and the
type of address pool.
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o CASM Coordinator looks up the remaining address pool in its local
database. It will then allocate a set of address pools to the DA.
Each address pool has a related lifetime.
o DA receives the Address Pool reply and use them for their purpose.
o If the lifetime of the address pool is going to expire, the DA
should issue an Address Pool Renew request to extend the lifetime,
including the IPv4, IPv6, Ports, etc.
o The Address Pool Report module keeps monitoring and reports the
current usage of all current address pools for each transition
mechanism. If it is running out of address pools, it can renew
for a newly allocated one. It can also release and recycle an
existing address pool if that address pool has not been used for a
specific and configurable time.
o When the connection of CASM Coordinator is lost or the CASM
Coordinator needs the status information of certain applications,
the CASM Coordinator may pre-actively query the DA for the status
information.
5.2.2. Interface modeling requirements
5.2.2.1. Initial Address Pool Configuration
+--------------+ +-----------------+
| Device | | CASM |
| Agent | | Coordinator |
+------+-------+ +--------+--------+
| |
+--------+-------+ |
|1.DA start-up | |
+---------+------+ |
| 2.Address Pool Request |
|------------------------------------------>|
| |
| +--------+-------+
| | 3. Check |
| | address pool |
| +--------+-------+
| 4.Address Pool Reply |
|<------------------------------------------|
| |
Figure 2: Initial Address Pool Configuration
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Figure 2 The procedure is as follows:
1. The DA checks whether there is already address pool configured in
the local site when it starts up. if no, it means the initial
start-up or the address pool has been released. if yes, the
address pool could be used directly.
2. The DA will initiate Address Pool request to the CASM
Coordinator. It can carry its desired size of address pool in
the request, or just use a default value. The address pool size
in the DA's request is only used as a hint. The actual size of
the address pool is totally determined by CASM Coordinator. It
will also carry the DA's identification, the type of transition
mechanism and the indication of port allocation support.
3. The CASM Coordinator determines the address pool allocated for
the DA based on the parameters received.
4. The CASM Coordinator sends the Address Pool Reply to the DA. It
will also distribute the routing entry of the address pool
automatically. In particular, if the newly received address pool
can be aggregated to an existing one, the routing should be
aggregated accordingly.
5.2.2.2. Address Pool Status Report
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+--------------+ +-----------------+
| Device | | CASM |
| Agent | | Coordinator |
+------+-------+ +--------+--------+
| |
+--------+-------+ |
|1.Monitor and | |
|count the status| |
+--------+-------+ |
| 2.Address Pool Status Report |
|--------------------------------------------->|
| +--------+-------+
| | 3. Record |
| | address pool |
| +--------+-------+
| 4.Address Pool Report Confirm |
|<---------------------------------------------|
| |
| |
Figure 3: Address Pool Status Report
Figure 3 Figure 3 illustrates the active address pool status report
procedure:
1. The DA will monitor and count the usage status of the local
address pool. The DA counts the address usage status in one
month, one week and one day, which includes the local address,
address usage ratio (peak and average values), and the port usage
ratio (peak and average values).
2. The DA reports the address pool usage status to the CASM
Coordinator. For example, it will report the address usage
status in one day, which contains the IP address, NAT44, address
list: 30.14.44.0/28, peak address value 14, average address usage
ratio 90%, TCP port usage ratio 20%, UDP port usage ratio 30% and
etc.
3. The CASM Coordinator records the status and compares with the
existing address information to determine whether additional
address pool is needed.
4. The CASM Coordinator will confirm the address pool status report
request to the DA. It will keep sending the address pool status
report request to the CASM Coordinator if no confirm message is
received.
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5.2.2.3. Address Pool Status Query
When the status of CASM Coordinator is lost or the CASM Coordinator
needs the status information of the DAs, the CASM Coordinator may
actively query the TD for the status information, as shown in step 1
of Figure 4. The following steps 2,3,4,5 are the same as the Address
Pool Status Report procedure.
+--------------+ +-----------------+
| Device | | CASM |
| Agent | | Coordinator |
+------+-------+ +--------+--------+
| |
| |
| 1.Address Pool Status Query |
|<---------------------------------------------|
| |
+--------+-------+ |
|2.Monitor and | |
|count the status| |
+--------+-------+ |
| 3.Address Pool Status Report |
|--------------------------------------------->|
| +--------+-------+
| | 4. Record |
| | address pool |
| +--------+-------+
| 5.Address Pool Report Confirm |
|<---------------------------------------------|
| |
| |
Figure 4: Address Pool Status Query
5.2.2.4. Address Exhaustion
When the DA uses up the addresses allocated, it will renew the
address pool request to the CASM Coordinator for an additional
address pool. The procedure is the same as the initial address pool
request.
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5.2.2.5. Address Pool Release
+--------------+ +-----------------+
| Device | | CASM |
| Agent | | Coordinator |
+------+-------+ +--------+--------+
| |
+--------+-------+ |
|1.Address pools | |
| not used for a| |
| long time | |
+--------+-------+ |
| 2.Address Pool Release Request |
|--------------------------------------------->|
| +--------+-------+
| |3. Update |
| | address pool |
| | database |
| +--------+-------+
| 4.Address Pool Release Notification |
|<---------------------------------------------|
+--------+-------+ |
|5. Reduce | |
| address pool | |
+--------+-------+ |
| 6.Address Pool Release Confirm |
|--------------------------------------------->|
| |
| |
Figure 5: Address Pool Release
Figure 5 illustrates the address pool release procedure:
1. The counting module in the DA checks that there are addresses not
used for a long time;
2. The DA sends the address pool release request to the CASM
Coordinator to ask the release of those addresses;
3. The CASM Coordinator updates the local address pool information
to add the new addressed released;
4. The CASM Coordinator notifies the TD that the addresses have been
release successfully;
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5. The DA will update the local address pool. If no Address Pool
Release Notification is received, the DA will repeat step 2;
6. The DA confirms with the CASM Coordinator that the address pool
has been released successfully.
6. Security Considerations
7. Acknowledgements
N/A.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
8.2. Informative References
[RFC6888] Perreault, S., Ed., Yamagata, I., Miyakawa, S., Nakagawa,
A., and H. Ashida, "Common Requirements for Carrier-Grade
NATs (CGNs)", BCP 127, RFC 6888, DOI 10.17487/RFC6888,
April 2013, <http://www.rfc-editor.org/info/rfc6888>.
Authors' Addresses
Chen Li
China Telecom
No.118 Xizhimennei street, Xicheng District
Beijing 100035
P.R. China
Email: lichen@ctbri.com.cn
Chongfeng Xie
China Telecom
No.118 Xizhimennei street, Xicheng District
Beijing 100035
P.R. China
Email: xiechf.bri@chinatelecom.cn
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Rakesh Kumar
Juniper Networks
1133 Innovation Way
Sunnyvale CA 94089
US
Email: rkkumar@juniper.net
Anil Lohiya
Juniper Networks
1133 Innovation Way
Sunnyvale CA 94089
US
Email: alohiya@juniper.net
Jun Bi
Tsinghua University
3-212, FIT Building, Tsinghua University, Haidian District
Beijing 100084
P.R. China
Email: junbi@tsinghua.edu.cn
Weiping Xu
Huawei Technologies
Bantian, Longgang District
shenzhen 518129
P.R. China
Email: xuweiping@huawei.com
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