Network Working Group C. Li
Internet-Draft C. Xie
Intended status: Informational China Telecom
Expires: September 7, 2017 J. Bi
Tsinghua University
W. Xu
Huawei Technologies
March 6, 2017
Interface to the Address Pool Management
draft-li-casm-address-pool-management-arch-00
Abstract
This document describes an mechanism for a standard, programmatic
interface for address pool management. With the remaining IPv4
address becoming more and more scattered, it is complicated to
manually configure the address pools on lots of Broadband Network
Gateways(BNGs) for operators. By introducing SDN/NFV in BNG, the
address pools can be allocated in a centralized way. It will not
only simplify the address management for operators, but also improve
the utilization efficiency of the address pool.
Status of This Memo
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provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 7, 2017.
Copyright Notice
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. Architectural Overview . . . . . . . . . . . . . . . . . . . 3
4. Initial Address Pool Configuration . . . . . . . . . . . . . 5
5. Address Pool Status Report . . . . . . . . . . . . . . . . . 7
6. Address Pool Status Query . . . . . . . . . . . . . . . . . . 8
7. Address Exhaustion . . . . . . . . . . . . . . . . . . . . . 8
8. Address Pool Release . . . . . . . . . . . . . . . . . . . . 8
9. Compatibility of different forms of devices . . . . . . . . . 10
10. Control Protocol consideration . . . . . . . . . . . . . . . 10
11. Security Considerations . . . . . . . . . . . . . . . . . . . 11
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
13.1. Normative References . . . . . . . . . . . . . . . . . . 11
13.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
The 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.
Another use case which needs to configure the address pools is IPv6
migration. For IPv6 transition mechanisms, e.g. DS-Lite, lw4over6,
etc., they all need to be configured with address pools as translated
routeable addresses. When high availability features, e.g. active-
active/active-standby failover mechanism, etc., are enabled for these
IPv6 transition mechanisms, different address pools need to be
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configured on each transition instance. This will further increase
the number of address pools need to be configured. Besides, the
occupation of the address pools may vary during different transition
periods, (e.g. at the early stage of IPv6 transition, IPv4 traffic
will normally occupy a great portion of the total traffic, while in
the later stage of IPv6 transition, IPv4 traffic will decrease and
the amount of IPv4 address pools will decrease accordingly.
There are other devices which may need to configure address pools as
well. For example, the Firewall need to configure the address pool
for acl/NAT process. The VPN also needs to configure the address
pools for end-users.
When SDN/NFV is introduced in the network, these devices (e.g. BNG,
CGN, firewall, VPN, etc.) will run as VNFs in virtualized
environment. A common centralized address management server can
interact with different VNFs and allocate address pools
automatically.
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:
APMS A management system which has a centralized databse manage
the overall address pools and allocate address pools to the device
in the devices.
DA A device agent in device, which contact with APM server to
manipulate address pool.
3. Architectural Overview
In this architecture, the Address Pool Management (APM) server is a
centralized address pool management server for operators to configure
the overall address pools. It maintains the address pool database
including the overall address pools (OAP) and the address pool
status(APS). Operators can configure its remaining address pools in
the OAP. They can also reserve some address pool for special-purpose
usage. The address pools status is to reflects the current usage of
the address pools for different devices. APM also has the interface
to configure the address pools to different devices dynamically.
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In each device, there is an device agent (DA) to contact with APM
server. 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.
+*********************+
| APM server |
| +------------+ |
| | Address DB | |
| +------------+ |
+***^*****^******^*^**+
| | |
| | |
+------------+ | +------------+
| | |
| | |
+------v------+ +------v------+ +------v------+
| +--------+ | | +--------+ | | +--------+ |
| | agent | | | | agent | | | | agent | |
| +----+---+ | | +----+---+ | | +----+---+ |
| | | | | | | | |
| v | | v | | v |
| +--------+ | | +---------+ | | +---------+ |
| | Local | | | | v6tra | | | | VPN | |
| | Conf | | | | instance| | | |instance | |
| +--------+ | | +----+----+ | | +---------+ |
+-------------+ | | | | | |
| v | | v | | v |
| +---------+ | | +---------+ | | +---------+ |
| | routing | | | | routing | | | | routing | |
| +---------+ | | +---------+ | | +---------+ |
+-------------+ +-------------+ +-------------+
BNG/vBNG v6tra/fw VPN
Figure 1: Interface to Address Pool Management (APM)
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. Initial Address Pool Configuration
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+--------------+ +-----------------+
| Device | |AddrPoolMangement|
| Agent | | Server |
+------+-------+ +--------+--------+
| |
+--------+-------+ |
|1.DA start-up | |
+---------+------+ |
| 2.Address Pool Request |
|------------------------------------------>|
| |
| +--------+-------+
| | 3. Check |
| | address pool |
| +--------+-------+
| 4.Address Pool Reply |
|<------------------------------------------|
| |
| |
Figure 2: Initial Address Pool Configuration
Figure 2 illustrates the initial address pool configuration
procedure:
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 APMS. 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 APMS. It will also carry the DA's
identification, the type of transition mechanism and the
indication of port allocation support.
3. The APMS determines the address pool allocated for the DA based
on the parameters received.
4. The APMS 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.
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5. Address Pool Status Report
+--------------+ +-----------------+
| Device | |AddrPoolMangement|
| Agent | | Server |
+------+-------+ +--------+--------+
| |
+--------+-------+ |
|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 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 APMS. 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 APMS records the status and compares with the existing
address information to determine whether additional address pool
is needed.
4. The APMS will confirm the address pool status report request to
the DA. It will keep sending the address pool status report
request to the APMS if no confirm message is received.
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6. Address Pool Status Query
When the status of APMS is lost or the AMS needs the status
information of the DAs, the APMS 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 | |AddrPoolMangement|
| Agent | | Server |
+------+-------+ +--------+--------+
| |
| |
| 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
7. Address Exhaustion
When the DA uses up the addresses allocated, it will renew the
address pool request to the APMS for an additional address pool. The
procedure is the same as the initial address pool request.
8. Address Pool Release
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+--------------+ +-----------------+
| Device | |AddrPoolMangement|
| Agent | | Server |
+------+-------+ +--------+--------+
| |
+--------+-------+ |
|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 APMS to ask
the release of those addresses;
3. The APMS updates the local address pool information to add the
new addressed released.
4. The APMS notifies the TD that the addresses have been release
successfully;
5. The DA will update the local address pool. if no Address Pool
Release Notification is received, the DA will repeat step 2;
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6. The DA confirms with the APMS that the addres pool has been
released successfully.
9. Compatibility of different forms of devices
As described in section 3, each device has its address pools, the
Address Pool Management (APM) server act as a centralized address
pool management server for operators to configure the overall address
pools of each devices. In this form of device, the user plane and
the control plane are integrated in the box. There are another form
of device, the control plane is separated from the 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. The control plane device, together with the
dependent multiple user plane devices, forms a "big" device. This
bigger device contacts with the APM server to manipulate IP address
pool. For example, the device acts as a server side when running the
NETCONF protocol between the device and the APM. It determines
whether the usage status of the IP address pool resource in device is
satisfies the condition. For example, the address pool resource of
device is not enough or excessive. It sends address pools resource
request to the APM server, and receives response with address pools
resource for this device allocated from APM server. Then it passes
the address pools resource to local instances. In addition, it
report the status of local address pool resource usage and update the
address pools requests, etc.
10. Control Protocol consideration
The I2APM architecture consists of two major distinct entities: APM
Server and network equipment with an APM Agent. In order to provide
address pool manipulations between these two entities, the I2APM
architecture calls for well-defined protocols for interfacing between
them. For compatibility with legacy network equipment, the
architecture reuse legacy protocol such as radius. While the IETF
may also choose to define one or more specific approaches to
manipulate address pool, such as NETCONF or RESTCONF with address
pool YANG data model.In modern network management system, the NETCONF
or RESTCONF is used widely, the device implements as the NETCONF or
RESTCONF server, and the network management system implements as the
NETCONF or RESTCONF client, that achieving more automated network
management.
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11. Security Considerations
12. Acknowledgements
N/A.
13. References
13.1. 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>.
13.2. Informative References
[RFC6674] Brockners, F., Gundavelli, S., Speicher, S., and D. Ward,
"Gateway-Initiated Dual-Stack Lite Deployment", RFC 6674,
DOI 10.17487/RFC6674, July 2012,
<http://www.rfc-editor.org/info/rfc6674>.
[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.bri@chinatelecom.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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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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