Internet DRAFT - draft-deng-overlay-routing-ps
draft-deng-overlay-routing-ps
Internet Engineering Task Force X. Fei, Ed.
Internet-Draft G. Li
Intended status: Informational Huawei
Expires: 13 July 2023 Y. Cui
Tsinghua University
9 January 2023
Overlay Routing Problem Statement
draft-deng-overlay-routing-ps-01
Abstract
This document considers the limitations of existing technologies in
addressing the challenges of low network latency. It analyzes the
problem of signaling redundancy on control plane and problem of non-
global optimal path selection policy for overlay network and explores
possible solutions.
Status of This Memo
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This Internet-Draft will expire on 13 July 2023.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Related Work . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Global Server Load Balancer Based on Smart DNS . . . . . 3
2.2. Intelligent Overlay Routing . . . . . . . . . . . . . . . 3
3. Challenges and Problem Statement . . . . . . . . . . . . . . 4
3.1. Signaling Redundancy on Control Plane . . . . . . . . . . 4
3.2. Non-global Optimal Path Selection Policy . . . . . . . . 6
4. Candidate Solution Directions . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. Additional Stuff . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
There are emerging mobile applications, such as online games, audio
and video, and AR (augmented reality)/VR (virtual reality), which
have higher requirements for low latency, throughput, and packet
loss. With the rapid development of mobile Internet services, the
research on mobile Internet architecture has become a hot topic. The
terminal industry, represented by device-edge-pipe-cloud devices with
ultimate interoperability experience in all-scenario, poses great
challenges to the current Internet and requires disruptive
technologies to support transformation.
This document analyzes some existing technologies related to
improving the user experience of real-time applications, and hope to
find a solution to improve the end-to-end transmission experience to
meet the increasing requirements of network delay.
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2. Related Work
There is a significant amount of previous work in terms of improving
the end-to-end transmission performance. Some are to control the
destination ends, and some are to control the network path. The
relevant work is presented in this section.
2.1. Global Server Load Balancer Based on Smart DNS
In the request process of Global Server Load Balancer (GSLB) Based on
Smart DNS, the root DNS forcibly forwards the DNS to the GSLB device.
The GSLB resolves the optimal IP address based on the server load and
the user's IP address, sends the DNS response to the local server,
and finally sends the response to the user.
GSLB based on smart DNS enables an application to control the
destination of requests but cannot control the path to the
destination. For example, if an application wants to further
optimize the path requested by a user due to security or performance
considerations, smart DNS cannot meet the preceding requirements.
The overlay network technology can further optimize the path to avoid
failure or congestion in the path to a certain extent. It is an
important means to improve the quality of Internet transmission and
user experience and achieve high-quality transmission.
2.2. Intelligent Overlay Routing
The Internet consists of multiple carriers, ISPs, and autonomous
domains, which causes the complex business relationships between
domains. The transmission paths of the Internet are affected by
business relationships and is not the shortest path in the network.
For example, transmission between two Asian nodes may be detoured to
Europe. This increases the end-to-end latency. At the same time,
the Internet routing is not aware of path performance, and thus it is
difficult to avoid failure or congestion in the path, or requires a
long convergence time.
The overlay network technology is proposed to find out the optimal
path of the Internet. Software forwarding units are deployed in data
centers in different areas of the Internet to connect to each other
and schedule each other. In this way, a new virtual overlay network
is constructed on the basis of the existing public network (underlay
network). An intermediate forwarding node may be referred to as a
forwarding relay or a point of presence (PoP) node.
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Intelligent overlay routing, the key of overlay network technology,
directly determines the transmission performance for users accessing
the overlay network. It selects appropriate forwarding nodes on the
overlay network to form an end-to-end optimal forwarding path for
data transmission.
In the existing intelligent overlay routing technologies, the optimal
path is determined by three subsystems: the ingress PoP selection
system, the egress PoP selection system, and the internal overlay
routing system. The optimal scheme is computed independently in each
subsystem, but the local optimal doesn't mean the global optimal.
The sum of each optimal scheme in subsystem can't figure out the best
network path. In addition, it takes expensive cost to maintain the
routing table status and invoke different systems to perform packet
header encapsulation and decapsulation for subsystems.
3. Challenges and Problem Statement
This section describes in detail some possible bottlenecks
encountered when dealing with low network latency.
3.1. Signaling Redundancy on Control Plane
Overlay routing can be divided into two segments: access segment and
backbone segment. The source in the access segment obtains the
address of the access controller through the DNS and requests the
address of the access point (ingress or egress). The access
controller selects an access point based on factors such as
geographic location and latency. The backbone controller in the
backbone segment updates the optimal path from any ingress to egress
in real time.
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+-----------------+
+-----------|access controller|--------------+
| +-----------------+ |
| | | |
| | | |
| | | |
| | +----+ +----+ | |
| | +------->|PoP4|-------|PoP3|<------+ | |
+---+ | | | +----+\ /+----+ | | |
|DNS| | | | | \ / | | | |
+---+ | | | | \ / | | | |
| | | | | \ | | | |
| | | | | / \ | | | |
| | | | | / \ | | | |
| | | | +----+/ \+----+ | | | +-----------+
+------+ | | |------->|PoP1|-------|PoP2|<------| | +->|destination|
|source|<-+ | | +----+ +----+ | | +-----------+
+------+ | | | |
| | | |
| | | |
| | +--------------------+ | |
| +-------|backbone conctroller|-----+ |
| +--------------------+ |
| |
access segment| backbone segment | access segment
| |
Figure 1: Overlay Routing
On the control plane, the source obtains the address of destination
and access controller through the DNS, requests for an access point
from the access controller, and sends the messages to the
destination. Multiple rounds of signaling interaction with the DNS
and the controller are required from connection establishment to
packet transmission. As shown in the figure, five rounds of
signaling interaction are needed and it is redundant.
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+------+ +---+ +-----------------+
|source| |DNS| |access controller|
+------+ +---+ +-----------------+
| | |
| 1a. request the address | |
| of destination | |
|-------------------------------->| |
| | |
| 1b. return the address | |
|<--------------------------------| |
| | |
|-------+ | |
| |2. select overlay network| |
| | to transmit data | |
|<------+ | |
| | |
| 3a. request the address of | |
| access controller | |
|-------------------------------->| |
| | |
| 3b. return the address | |
|<--------------------------------| |
| | |
| 4a. request the ingress and |
| egress PoP from the controller |
|-------------------------------------------------------->|
| | |
| 4b. return the ingress and egress PoP |
|<--------------------------------------------------------|
| | |
| 5. Encapsulate packets based on the ingress |
| address and send the packets |
|-------------------------------------------------------->|
| | |
Figure 2: Signaling Redundancy on Control Plane
3.2. Non-global Optimal Path Selection Policy
In the prior art, an optimal path is calculated in several parts.
That is, the Internet gets the optimal routing in access segment and
backbone segment, and strings them together as the optimal path.
However, the optimal path calculated in this way is not an optimal
end-to-end path.
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+-+ 120.5ms +-+ 19.9ms +-+
|A|-------------|B|------------|C|
+-+ +-+ +-+
| |
| |
90ms | |4.9ms
| |
| |
+-+ +-+ +-+
|D|-------------|E|------------|F|
+-+ 153.4ms +-+ 15.3ms +-+
Figure 3: Non-global Optimal Path Selection Policy
For example, the nearest PoP would be chosen as the access point
(ingress/egress) according to the latency. Take A as the source and
C as the destination, and then an optimal path is calculated by the
existing overlay routing technology: A->D->E->F->C (263.7ms).
However, it is clear that there is a better path here: A->B->C
(140.4ms).
4. Candidate Solution Directions
This section seeks for the possible breakthrough point to achieve
lower latency and improve the user experience in real-time
applications.
As mentioned above, the problem of signaling redundancy on control
plane and problem of non-global optimal path may be the obstacles to
reduce lower network latency and improve user's experience. A
possible solution direction is presented below.
To solve the problem of non-global optimal path, the source
calculates the global optimal overlay path and delivers to the
destination.
For details, the source directly delivers routing through DNS. The
DNS is redirected to the controller to request an optimal path, and
the controller returns a multi-dimensional path vector. In this way,
the users can control a delivery path at the source. Also, the
intermediate forwarding nodes don't need to maintain any routing
table, because all routing status information may be included in a
private header of a data packet generated by the source.
5. IANA Considerations
Request to IANA will be added later.
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6. Security Considerations
Security issues will be considered later in the design.
7. References
7.1. Normative References
7.2. Informative References
Appendix A. Additional Stuff
This becomes an Appendix.
Authors' Addresses
XinCai Fei (editor)
Huawei
No. 410, Jianghong Road, Binjiang District
Hangzhou
China
Email: feixincai1@huawei.com
Geng Li
Huawei
HuaWei Bld., No.3 Xinxi Rd.
Beijing
China
Email: ligeng23@huawei.com
Yong Cui
Tsinghua University
4-104, FIT Building
Beijing
China
Email: cuiyong@tsinghua.edu.cn
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