| 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
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.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any 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 December 26, 2020.
Copyright (c) 2020 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 (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
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 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.
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:
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:
There are several requirements for DOTS server deployment that may be , and is consistent with other drafts:
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.
/<===>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
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.
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.
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.
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.
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.
The following parameters will be required by orchestrator:
The recommended approach here is to redirect traffic and flow cleaning.
The following parameters will be required by orchestrator:
The recommended approach here is to use router for disposition.
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.
+-------------+ +-------------+
| 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]
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.
+-------------+
| 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.
TBD
TBD
TBD
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC7950] | Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016. |