Internet DRAFT - draft-chen-dots-server-hierarchical-deployment
draft-chen-dots-server-hierarchical-deployment
DOTS M. Chen
Internet-Draft Li. Su
Intended status: Informational China Mobile
Expires: December 26, 2020 June 24, 2020
A method for dots server deployment
draft-chen-dots-server-hierarchical-deployment-03
Abstract
As DOTS is used for DDoS Mitigation signaling, there are different
deployment scenarios for DOTS agents deployment depending on the
network topology. This document made recommandations for DOTS Server
deployment, include ISP and enterprise deployment scenarios. The
goal is to provide some guidance for DOTS agents deployment.
Status of This Memo
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This Internet-Draft will expire on December 26, 2020.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. DOTS server Considerations . . . . . . . . . . . . . . . . . 3
4. DOTS server deployment inside an ISP . . . . . . . . . . . . 4
4.1. DOTS Agents Deployment . . . . . . . . . . . . . . . . . 4
4.2. DOTS Agents interfaces . . . . . . . . . . . . . . . . . 7
4.2.1. Bandwidth consuming attack . . . . . . . . . . . . . 8
4.2.2. Host resource consuming attack . . . . . . . . . . . 8
5. DOTS server deployment between ISPs . . . . . . . . . . . . . 8
6. DOTS server deployment for Enterprise . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
DDoS Open Threat Signaling (DOTS) is a protocol to standardize real-
time signaling, threat-handling
requests[I-D.ietf-dots-signal-channel], when attack target is under
attack, dots client send mitigation request to dots server for help,
If the mitigation request contains enough messages of the attack,
then the mitigator can respond very effectively.
In the architecture draft[I-D.ietf-dots-architecture], when comes to
the deployment topic, it says this does not necessarily imply that
the attack target and the DOTS client have to be co-located in the
same administrative domain, but it is expected to be a common
scenario. Although co-location of DOTS server and mitigator within
the same domain is expected to be a common deployment model, it is
assumed that operators may require alternative models.
In the DOTS server discovery draft[I-D.ietf-dots-server-discovery],
it is says that a key point in the deployment of DOTS is the ability
of network operators to be able to configure DOTS clients with the
correct DOTS server(s) information consistently.
In the DOTS multihoming draft[I-D.ietf-dots-multihoming], it provides
deployment recommendations for DOTS client and DOTS gateway, it is
says when conveying a mitigation request to protect the attack
target, the DOTS client among the DOTS servers available Must select
a DOTS server whose network has assigned the prefixes from which
target prefixes and target IP addresses are derived. This implies
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that id no appropriate DOTS server is found, the DOTS client must not
send the mitigation request to any DOTS server. So in this document,
we give some dots server deployment consideration as the title
suggests we prefer hierarchical deployment.
This is DOTS server deployment guidance for operators, We've written
about our experience as an ISP, and we hope that other scenarios will
contribute as well.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119]
The readers should be familiar with the terms defined in
[I-D.ietf-dots-requirements] [I-D.ietf-dots-use-cases]
The terminology related to YANG data modules is defined in [RFC7950]
In addition, this document uses the terms defined below:
dots svr: abbreviation of dots server.
ISP: Internet service provider.
Orchestrator: With the function of DOTS server that can receive
messages from clients and made decisions for mitigators selection.
netflow/ipfix collector: Flow collector used for DDoS attack
detection.
3. DOTS server Considerations
When take dots server deployment into consideration, one thing must
be involved is mitigator that can provide DDoS mitigation service.
So far, how many network devices can play the role of mitigator, we
make a summerized list as follows:
o Router.
o Special cleaning equipment, such as flow clean device and clean
center.
o Network security equipment, such as firewall, IPS and WAF.
o Servers that websites can hidden behind them.
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There are several requirements for DOTS server deployment that may be
, and is consistent with other drafts:
o DOTS server and mitigator are in the same administrative domain.
o DOTS server can go directly to the mitigator which had best go
through without any other DOTS agents.
o DOTS server has the permissions for scheduling on mitigators.
o DOTS server has the ability to know the address of attack target
belong to which mitigator, if DOTS server hasn't matched attack
target to mitigators, DOTS server need to configure default
mitigators.
4. DOTS server deployment inside an ISP
4.1. DOTS Agents Deployment
From the internal structure of ISP, the whole network can abstract as
a three-level network logically. The hierarchy of the network can be
adjusted according to the size of the network. In addition to having
its own business, the upper network is responsible for connectivity
between the lower networks. It's worth noting that there are usually
Internet Data Centers(IDC), high bandwidth demand customers(such as
online game companies) and VIP customer centers(such as financial
clients) distributed in each level network, but most of these
services are typically placed on a secondary network.
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/<===>Mitigator
__(RT)___
/ \
/ primary \
----------------
|
/ \
/ \ /<===>Mitigator
_______ _(RT)_
/ \ / \
/ Second \ / Second \
----------- ----------
/ / \
/<==>Mitigator / \
_(RT) ___ _(RT)
/ \ / \ / \
/ Third \ /Third\ /Third \
--------- ------- --------
Figure 1: ISP multilevel network
There are mitigators such as cleaning centers in each regional
network. Select the second level network for detailed description,
the cleaning equipment is attached to the exit router, and Detector
is concatenated on the link, usually detector could be one type of
netflow/ipfix collector, sometimes could be firewall or IDS(Intrusion
Detection System), they could able to find some types of DDoS
attacks. Attacks from two different sources occur inside the Second
network as follows:
(Router)<=====>Flow Clean Device
^^
||(Detector)
________||__________
( || )
( #IDC# ++<<<<<<DDoS )
( #VIP# )
( #other service# )
( ^^ )
_______________||________
||
DDoS>>>>>>>++
Figure 2:Two DDoS attack paths
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There are only two attack source paths under this structure: One is
an attack launched within the network, flowing to the upper level of
the network. The other is that low-level networks launch attacks and
flow to the upper level of networks, and pass through the
intermediate level network. Internal DDoS attacks is out of scope in
this draft.
In this case, DOTS clients might consider to be deployed internally.
When DDoS attack occurs, attack target inside the Second network may
sense being attacked, such as customer complaints and the processing
speed is slower than before. attack target then inform Detector(DOTS
client) making mitigation request to DOTS server(Router), and the
traffic mitigation is then triggered. DOTS server and Mitigator are
in the same administrative domain.
(The Secondary network)
^
||
(Router)<=====>Flow Clean Device
(DOTS Server) (Mitigator)
^
||
|/
(DOTS Client)
Detector
________||__________
( || 1 )
( #IDC# ++<<<<<<DDoS )
( #VIP# )
( #other service# )
( ^^ )
_______________||_________
-------------------2||--------------
(The Third network) ||
||
DDoS>>>>>>>++
Figure 3: DOTS Agents Deployment
When DDoS Attack path case 1 occurs, the DOTS client in the same
network will send mitigation requests to DOTS server which installed
in the same area within export router.
When DDoS Attack path case 2 occurs, the Dots server in the Third
network export router will receive mitigation request. If the first
level of protection is not effective enough, the DOTS server in the
upper network will also receive mitigation requests.
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If attacks on the same attack target are found both in adjacent
areas, there are two strategies for the mitigators' selection, then
found the best mitigation node for different scenes.
o Near Attack Source Mitigation(NASM), NASM means that the
mitigation is performed closest to the source of the attack, this
usually happens at the entrance to the edge of the network. This
approach can block attack flow at the source and protect network
bandwidth maximumly, but requires the ability to operate the
entire network. This principle is more suitable for large-traffic
attack mitigation.
o Near Attack Target Mitigation(NATM), NATM means that the
mitigation is performed closest to the attack target, This is the
easiest and most direct way, but it will cause the attack flow
long-distance transmission, occupy the bandwidth along the link,
more likely to cause link congestion. This principle is more
suitable for low-traffic attack mitigation.
Normally, The lower network the target in, the easier it is to alert.
Because the higher network the attack target in, the greater the
bandwidth of the pipeline. When multiple mitigators need to work
together, then need orchestrator to take on the role for scheduling.
Because the importance of the orchestrator, it is suggested to
consider bakeup mechanisms or heartbeat technology to ensure
continuity and security.
How does DOTS client can find DOTS servers, we can reference the DOTS
server discovery draft[I-D.ietf-dots-server-discovery], Static
configuration or dynamic discovery depends on the actual scenario and
the size of the network.
4.2. DOTS Agents interfaces
In the dots use case draft[I-D.ietf-dots-use-cases], it is says the
orchestrator analyses the various information it receives from DDoS
telemetry system, and initiates one or multiple DDoS mitigation
strategies. In the telemetry draft, all the telemetry informations
are contained and some parameters can be used to make decisions.
This section made a discussion on which attributes could be used in
orchestrator for scheduling.
We suggest orchestrator has three capabilities and reuse the method
of registration and notification in signal channel to know all the
related mitigators capability and residue capability:
1.Can get the neflow/ipfix collector's telemetry informations.
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2.Can get the capabilities of each mitigator, it means the initial
capacity, this means that with each addition of mitigator there needs
to be a protocol that can push this information to orchestrator, we
recommend using DOTS signal channel to transfer initial capacity.
3.When mitigation finished, mitigator can inform orchestrator that
mitigation is finished and capacity has been released, also we
recommend using DOTS signal channel to transfer.
4.2.1. Bandwidth consuming attack
The following parameters will be required by orchestrator:
o top-talker
o source-prefix
o total-traffic
o total-attack-traffic
o total-pipe-capability
The recommended approach here is to redirect traffic and flow
cleaning.
4.2.2. Host resource consuming attack
The following parameters will be required by orchestrator:
o top-talker
o source-prefix
The recommended approach here is to use router for disposition.
5. DOTS server deployment between ISPs
Because of global connectivity, the coexistence of different
operators is very common, coordination between operators across
networks is very important. Interdomain attacks occur frequently, We
recommend deploying the DOTS server at the access point.
o DDoS attack from one of other ISPs, for example, ISP A received
DDoS attack from ISP B or ISP C, then dots server inside ISP B or
ISP C will receive the mitigation requests.
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o DDoS attacks from two or more of other ISPs,for example, ISP A and
ISP B both start ddos attack to ISP C, then dots server A and dots
server B will both receive mitigation request from dots client C.
+-------------+ +-------------+
| ISP A | | ISP B |
| +---------+ | | +---------+ |
| C/S | | C/S |
+-------------+ +-------------+
| |
+---------------------------+
|
|
+-------------+
| C/S |
| +---------+ |
| ISP C |
+-------------+
Figure 4: DOTS Agents Deployment between ISPs
When an DDoS attack occurs, depending on the direction of the attack,
the corresponding server is required for mitigation, DOTS server can
use call home to find the source of the DDoS
attacks[I-D.ietf-dots-signal-call-home]
6. DOTS server deployment for Enterprise
In addition to operators taking advantage of the pipeline to make a
contribution to DDoS attack mitigation, there are also enterprise-
level DDoS attack mitigation solutions. It's usually a cloud service
and a large number of distributed nodes are deployed to protect their
customers from DDoS attack, customers' websites can be hidden behind
the nodes, usually the internet game companies and the live streaming
company will choose this way.
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+-------------+
| ISP |
| +---------+ |
| |dots svr | |
+-------------+
|
|
+-------------+
| Anti-D Node |
+-------------+
|dots client|
+-----------+
|
|
+-------------+
|attack target|
+-------------+
*Anti-D is for Anti-DDoS
Figure 5: Deployment for Enterprise and ISP
When enterprise-level anti-DDos nodes are unable to mitigate the DDoS
attack, they can trigger DOTS client which integrated in the Anti-D
Node to send mitigation request to ISP's DOTS server.
7. Security Considerations
TBD
8. IANA Considerations
TBD
9. Acknowledgement
TBD
10. References
10.1. 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,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
10.2. Informative References
[I-D.ietf-dots-architecture]
Mortensen, A., Reddy.K, T., Andreasen, F., Teague, N., and
R. Compton, "Distributed-Denial-of-Service Open Threat
Signaling (DOTS) Architecture", draft-ietf-dots-
architecture-18 (work in progress), March 2020.
[I-D.ietf-dots-multihoming]
Boucadair, M., Reddy.K, T., and W. Pan, "Multi-homing
Deployment Considerations for Distributed-Denial-of-
Service Open Threat Signaling (DOTS)", draft-ietf-dots-
multihoming-04 (work in progress), May 2020.
[I-D.ietf-dots-requirements]
Mortensen, A., K, R., and R. Moskowitz, "Distributed
Denial of Service (DDoS) Open Threat Signaling
Requirements", draft-ietf-dots-requirements-22 (work in
progress), March 2019.
[I-D.ietf-dots-server-discovery]
Boucadair, M. and T. Reddy.K, "Distributed-Denial-of-
Service Open Threat Signaling (DOTS) Agent Discovery",
draft-ietf-dots-server-discovery-10 (work in progress),
February 2020.
[I-D.ietf-dots-signal-call-home]
Reddy.K, T., Boucadair, M., and J. Shallow, "Distributed
Denial-of-Service Open Threat Signaling (DOTS) Signal
Channel Call Home", draft-ietf-dots-signal-call-home-08
(work in progress), March 2020.
[I-D.ietf-dots-signal-channel]
Reddy.K, T., Boucadair, M., Patil, P., Mortensen, A., and
N. Teague, "Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel Specification", draft-
ietf-dots-signal-channel-41 (work in progress), January
2020.
[I-D.ietf-dots-use-cases]
Dobbins, R., Migault, D., Moskowitz, R., Teague, N., Xia,
L., and K. Nishizuka, "Use cases for DDoS Open Threat
Signaling", draft-ietf-dots-use-cases-23 (work in
progress), May 2020.
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Authors' Addresses
Meiling Chen
China Mobile
32, Xuanwumen West
BeiJing
,
BeiJing
100053
China
Email:
chenmeiling@chinamobile.com
Li Su
China Mobile
32, Xuanwumen West
BeiJing
100053
China
Email:
suli@chinamobile.com
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