Internet DRAFT - draft-kang-tcpm-accurate-data-scheduling-by-server
draft-kang-tcpm-accurate-data-scheduling-by-server
TCP Maintenance and Minor Extensions J. Kang
Internet-Draft Q. Liang
Intended status: Informational X. Fei, Ed.
Expires: 13 July 2023 Huawei
9 January 2023
Accurate Data Scheduling by Server in MPTCP
draft-kang-tcpm-accurate-data-scheduling-by-server-04
Abstract
This document defines a new mechanism that enables MPTCP server to
send requests to MPTCP client for data scheduling between specified
subflows during a MPTCP session.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Typical flows for accurate data scheduling by server . . . . 3
3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Traffic switching to a newly-added network interface . . 5
3.2. Traffic switching to a network interface already in the
session . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. MP_Navigation Option . . . . . . . . . . . . . . . . . . . . 6
4.1. Option Format . . . . . . . . . . . . . . . . . . . . . . 6
5. Data scheduling on client when receiving MP_Navigation . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
MPTCP protocol is being deployed in various networks. In most
scenarios, MPTCP scheduling strategies for subflows are implemented
on client considering RTT and congestion, or sending packets
redundantly. MPTCP server does not participate in such decision-
making.
However, in actual deployment, MPTCP server is configured with
multiple network interfaces and these network interfaces are from
different operators. There are some scenarios in which MPTCP server
wants to set scheduling algorithms on these network interfaces based
on its own rules, network planning and operating policies. These
scheduling algorithms need to be passed to the MPTCP client and
executed on the client during a MPTCP session. Requirements for
these use cases are described below:
* Network fault prevention. Server tools can help detect quality of
each deployed network interfaces including packet loss, delay and
jitter. If key performance indicators (KPI) of one network
interface becomes worse, MPTCP server hopes to instruct MPTCP
client to switch the traffic into another network interface with
better KPI.
* A new entrance is deployed or an emergency entrance of 5G card is
added during a MPTCP session. In this case, MPTCP server may hope
to lead existing traffic to this newly added network interface.
One purpose is to test this new network in trial operation. Other
purposes include avoiding congestion and improving transmission
reliability on existing networks. For example, MPTCP server is
using network of Operator A for data transmission and a network of
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operator B is added when data traffic increases. At this time,
MPTCP server wants to arrange part of traffic of Operator A to
Operator B. In this case, the network of Operator B is the target
network.
* Value-added services. This requirement comes from operating
policies of operators. MPTCP server is required to help provide
its customers with diversified services in order to satisfy
individual demand. For example,it should be possible that MPTCP
server can indicate MPTCP client to switch VIP users' traffic to a
network interface with better KPIs.
* Another typical scenario is that MPTCP server hopes to adjust
traffic to a specific subflow because of the changes in network
cost, for example, the expiration of discounts. This requirement
also comes from the operating policies of operators.
Currently, there are two implementations related to these
requirements. [RFC8684] defines REMOVE_ADDR Option to delete one
address during a MPTCP session but it will close all subflows bound
to this address. draft-hoang-mptcp-sub-rate-limit-00 proposes a
Subflow Rate Limit Option which can be used by sender to receiver for
setting the rate of one subflow to zero.
For the use cases in this document, existing technologies are
somewhat inadequate because they do not provide a clear indication of
which subflow to switch to.
2. Typical flows for accurate data scheduling by server
An accurate data scheduling mechanism for MPTCP server is proposed in
this document. Two typical flows are illustrated in Figure 1 and
Figure 2.
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+--------+ +--------+
| Client | | Server |
+--------+ +--------+
| |
|<----Session setup with subflows----->|
| |
| Determine address ID
| for target network interface
| |
|<--Sending MP_Navigation for request--|
| on one ongoing subflow |
| |
Determine target subflow |
by address ID in MP_Navigation |
| |
Traffic switching to |
the target subflow |
| |
|----Data transfer is swichted to----->|
| the target subflow of |
| target network interface |
| |
| |
Figure 1: Server requests client to perform traffic switching
+--------+ +--------+
| Client | | Server |
+--------+ +--------+
| |
|<---Subflow with diverted traffic --->|
| is still kept alive |
| |
| Determine to cancel MP_Navigation
| for target network interface
| |
|<----Sending MP_Navigation on the-----|
| subflow with diverted traffic |
| for cancellation |
| |
Cancel traffic switching to |
target network interface |
in the MP_Navigation |
| |
|-----Continue data transfer over----->|
| the subflow with diverted traffic |
| |
| |
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Figure 2: Server sends a request to client to cancel previous
navigation setting
For the use case of adding a new network interface to a MPTCP session
for data shceduling, normal process of ADD_ADDR should be executed
before traffic switching.
If it is determined to cancel the data switching on a subflow, the
client should delete the navigation information for it. Navigation
information is generated by MPTCP client and is used to determine the
target subflow for data switching based on the address ID of the
target network interface.
After data switching, if the subflow with diverted traffic is
disconnected, the client should delete the navigation and
configuration information for it. The navigation information is
generated by the client and is used to determine the target subflow
for data switching based on the address ID of the target network
interface.
3. Examples
3.1. Traffic switching to a newly-added network interface
Four subflows have been established between client and server that
are <IP1, IP3>, <IP2, IP3>, <IP1, IP4> and <IP2, IP4>. On the
client, IP1 and IP2 are the address IDs for WiFi and a cellular
network. On the server, IP3 and IP4 are the address IDs for Ethernet
and WiFi. When a new 5G network is deployed on the server, the
server can switch the data traffic on the subflow <IP2, IP4> to the
destination IP5 corresponding to 5G. In this case, the target
network interface is IP5.
3.2. Traffic switching to a network interface already in the session
Four subflows have been established between client and server that
are <IP1, IP3>, <IP2, IP3>, <IP1, IP4> and <IP2, IP4>. On the
client, IP1 and IP2 are the address IDs for WiFi and a cellular
network. On the server, IP3 and IP4 are the address IDs for Ethernet
and WiFi. Server tool detects that KPI for IP4 is better now so the
server can switch data traffic on the subflow <IP1, IP3> to the
destination IP4.
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4. MP_Navigation Option
MP_Navigation option is defined and sent from server to force client
to switch traffic from the subflow over which the option was received
to a target subflow, or to cancel traffic switching when it is not
required. MP_Navigation option includes a Flag 'R' to distinguish
this two functions. If it is set, the target subflow is determined
through the Address ID of the target network interface in
MP_Navigation option.
MP_Navigation option can be sent in ACK.
Noted that if MP_Navigation option is not supported by the MPTCP
client, it should be omitted when received.
4.1. Option Format
The format of the MP_Navigation option is depicted in Figure 3:
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------+---------------+-------+-------+---------------+
| Kind | Length |Subtype|r|R|E|B| Address ID |
+---------------+---------------+-------+-------+---------------+
Figure 3: MP_Navigation Option
Subtype: a new subtype should be allocated to indicate MP_Navigation
Option.
Flag 'r': reserved for future usage.
Flag 'R': when set, defines the content of this option, as follows:
* When value of 'R' is set to zero, it means that the server wants
to use this option to inform client of data scheduling policy and
the client will perform traffic switching as requested by the
server. When value of 'R' is set to 1, the server requests to
cancel current data scheduling policy on client and the client
will delete corresponding navigation information to this Address
ID.
Flag 'E': exists to provide reliability for this option (like that in
"ADD_ADDR").
Flag 'B': indicates whether the subflow over which the option is
received is a backup one (that is compatiable with the value by
MP_PRIO).
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Address ID: Address ID in MP_Navigation Option is used to identify
the address ID of target network Interface. When the client receives
the MP_Navigation Option, it will determine the target network
interface by the Address ID. Address ID may map to one or more
ongoing subflows and the client will select one for data transfer by
its local strategies.
5. Data scheduling on client when receiving MP_Navigation
This section will be finished later.
6. IANA Considerations
IANA is requested to assign a MPTCP option subtype for the
MP_Navigation option.
7. Security Considerations
Since MP_Navigation option is neither encrypted nor authenticated,
on-path attackers and middleboxes could remove, add or modify the
MP_Navigation option on observed Multipath TCP connections.
8. References
8.1. Normative References
[RFC8684] Ford, A., Raiciu, C., Handley, M., Bonaventure, O., and C.
Paasch, "TCP Extensions for Multipath Operation with
Multiple Addresses", RFC 8684, DOI 10.17487/RFC8684, March
2020, <https://www.rfc-editor.org/info/rfc8684>.
Authors' Addresses
Jiao Kang
Huawei
Email: jiao_kang2022@163.com
Qiandeng Liang
Huawei
No. 207, Jiufeng 3rd Road, East Lake High-tech Development Zone
Wuhan
China
Email: liangqiandeng@huawei.com
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XinCai Fei (editor)
Huawei
No. 410, Jianghong Road, Binjiang District
Hangzhou
China
Email: feixincai1@huawei.com
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