Multi-Stage Transparent Server Load Balancing
draft-matsuhira-mslb-14
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Author | Naoki Matsuhira | ||
| Last updated | 2023-04-04 | ||
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draft-matsuhira-mslb-14
Network Working Group N. Matsuhira
Internet-Draft WIDE Project
Intended status: Informational 4 April 2023
Expires: 6 October 2023
Multi-Stage Transparent Server Load Balancing
draft-matsuhira-mslb-14
Abstract
This document specifies Multi-Stage Transparent Server Load Balancing
(MSLB) specification. MSLB make server load balancing over Layer3
network without packet header change at client and server. MSLB make
server load balancing with any protocol and protocol with encription
such as IPsec ESP, SSL/TLS.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
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 6 October 2023.
Copyright Notice
Copyright (c) 2023 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.
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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 Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Traditional load balancing method . . . . . . . . . . . . . . 2
3. Architecture of MSLB . . . . . . . . . . . . . . . . . . . . 3
4. configuration . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. basic configuration . . . . . . . . . . . . . . . . . . . 4
4.2. one arm configuration . . . . . . . . . . . . . . . . . . 5
5. mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. address translation mode . . . . . . . . . . . . . . . . 6
5.2. encapsulation mode . . . . . . . . . . . . . . . . . . . 9
6. Ingress filtering environment . . . . . . . . . . . . . . . . 12
7. Characteristic . . . . . . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9. Security Considerations . . . . . . . . . . . . . . . . . . . 14
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
11. Normative References . . . . . . . . . . . . . . . . . . . . 14
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
This document specifies Multi-Stage Transparent Server Load Balancing
(MSLB) specification.
MSLB provide server load balancing function over Layer3 network
without packet header change at client and server. MSLB work with
any protocol and protocol with payload encription such as IPsec ESP,
SSL/TLS.
2. Traditional load balancing method
There are several load balancing technique, such as round robin DNS,
IP Anycasting [RFC1546] and destination address translation.
Figure 1 shows load balancing system with typical server load
balancer with destination address translation technique.
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+---------+ +--------+
| +---+ Server |
+---------+ +----------+ | | +--------+
| | | | | | :
+--------+ | | | Server | | | +--------+
| Client +---+ Network +---+ Load +---+ Network +---+ Server |
+--------+ | | | Balancer | | | +--------+
| | | | | | :
+---------+ +----------+ | | +--------+
| +---+ Server |
+---------+ +--------+
Figure 1
It is well-known that Network address translator break internet
transparency [RFC2775] and have a application dependency [RFC2993]
characteristic.
Some server load balancer use application data, so with IPsec ESP,
SSL/TLS, this mechanisms may not work well.
3. Architecture of MSLB
Load balancing is the tecnique that distribute packet to multiple
server. For packet distribution, destination addresss translation
technique is useful, however this technique itself break internet
transparency.
After distribution, if write back to the original destination address
may possoble, it is possible to recover transparency. This is the
basic idea and architecture of MSLB. Figure 2 shows architecture of
MSLB.
Client ---- overwrite +---------- write back ----- server
destination |
address + --------- write back ----- server
|
: : :
+ --------- write back ----- server
Figure 2
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This method process only destination address of IP header. This
method can be applied to both IPv4 and IPv6.
4. configuration
4.1. basic configuration
Figure 3 shows basic server load balancing system with MSLB. This
case two-stage configuration with one MSLB-F and one-stage many MSLB-
Bs.
+-------+ +------+ +------+
| +---+MSLB-B+---+Server|
+-------+ +------+ | | +------+ +------+
| | | | | | : :
+------+ | | | | | | +------+ +------+
|Client+---+Network+---+MSLB-F+---+Network+---+MSLB-B+---+Server|
+------+ | | | | | | +------+ +------+
| | | | | | : :
+-------+ +------+ | | +------+ +------+
| +---+MSLB-B+---+Server|
+-------+ +------+ +------+
Figure 3
MSLB-F is front function of MSLB and translate destination address to
one of the address of MSLB-B. BSLB-B s backend function of MSLB and
translate destination address to the original server address, i.e.
address of MSLB-F. The IP address of MSLB-F and all server is the
same value.
MSLB-F may multi-stage configuration. Figure 4shows three stage
configuration with two-stage MSLB-F and one-stage many MSLB-Bs.
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+---+ +------+ +------+
| |--+MSLB-B+--+Server|
+---+ | | +------+ +------+
| | +----+ |Net| : :
+---+ +----+ | | |MSLB| | | +------+ +------+
| | | | | |--+ -F +--+ |--+MSLB-B+--+Server|
+------+ | | | | | | +----+ +---+ +------+ +------+
|Client+--+Net+--+MSLB+--+Net|
+------+ | | | -F | | | +----+ +---+ +------+ +------+
| | | | | +--+MSLB+--+ |--+MSLB-B+--+Server|
+---+ +----+ | | | -F | | | +------+ +------+
| | +----+ |Net| : :
+---+ | | +------+ +------+
| |--+MSLB-B+--+Server|
+---* +------+ +------+
Figure 4
4.2. one arm configuration
Figure 5shows one arm configuration of server load balancing system
with MSLB.
+---------+
| |
| MSLB-F |
| |
+----+----+
|
+----+----+ +--------+ +--------+
| +---+ MSLB-B +---+ Server |
| | +--------+ +--------+
| | : :
+--------+ | | +--------+ +--------+
| Client |-----+ Network +---+ MSLB-B +---+ Server |
+--------+ | | +--------+ +--------+
| | : :
| | +--------+ +--------+
| +---+ MSLB-B +---+ Server |
+---------+ +--------+ +--------+
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Figure 5
MSLB-F is front function of MSLB and translate destination address to
one of the address of MSLB-B. BSLB-B s backend function of MSLB and
translate destination address to the original server address, i.e.
address of MSLB-F. The IP address of MSLB-F and all server is the
same value.
This configuration, MSLB-F is connecting to the network with single
link, that is one arm configuration. This case, retuen packet, i.e.
packet from server to client does not pass through the MSLB-F.
5. mode
MSLB have two mode, one is address translation mode, and the other is
encapsulation mode.
5.1. address translation mode
This mode using address translation technique.
Figure Figure 6 shows packet processing with address translation
mode.
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+-------+ +------+ +------+
| +---+MSLB-B+---+Server|
+------+ | | | IP_B1| | IP_S |
|Client| +-------+ +------+ | | +------+ +------+
| IP_C1+---+ | | | | |
+------+ | | | | | | +------+ +------+
|Network| |MSLB-F|---+Network+---+MSLB-B+---+Server|
| +---+ | | | | IP_B2| | IP_S |
+------+ | | | IP_S | | | +------+ +------+
|Client+---+ | | | | |
| IP_C2| +-------+ +------+ | | +------+ +------+
+------+ | +---+MSLB-B+---+Server|
| | | IP_B3| | IP_S |
+-------+ +------+ +------+
: :
: :
+------+----+ : +------+----+ :+------+----+
| data | IP | : | data | IP | :| data | IP |
+------+----+ : +------+----+ :+------+----+
----------------------> : --------------------> : ------------>
src = IP_C1 : src = IP_C1 : src = IP_C1
dst = IP_S : dst = IP_B1 : dst = IP_S
: :
+------+----+ : +------+----+ :+------+----+
| data | IP | : | data | IP | :| data | IP |
+------+----+ : +------+----+ :+------+----+
<--------------------- -: <-------------------- : <------------
src = IP_S : src = IP_S : src = IP_S
dst = IP_C1 : dst = IP_C1 : dst = IP_C1
: :
Figure 6
In this figure, to the Client, IP address is allocated IP_C1, IP_C2,
and server IP address is IP_S. This case, IP_S is also allocate to
all servers and MSLB-F. And to the MSLB-B, IP_B1, IP_B2, IP_B3 is
allocated. These allocation is shown in upper part of Figure 6.
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Lower part of Figure 6 shows packet transfered between client and
server. From Client to the Server, only destination address is
translate, MSLB-F translate from IP_S to IP_B1, and MSLB-B translate
from IP_B1 to IP_S. Then the destination address of packet which
send client and the destination address of packet which recieve
server is same address. That mean, transparency is remained.
Return packet, i.e., from server to the client is not translate, just
forwarded.
In the Internet, Client IP address and server IP address must Global
IP address, however, IP address of MSLB-B may private IP address.
+--------------------+----------+-------------------------+
| Source IP address | net mask | destination IP address |
+--------------------+----------+-------------------------+
| IP_C1 | | IP_B1 |
+--------------------+----------+-------------------------+
| IP_C2 | | IP_B2 |
+--------------------+----------+-------------------------+
| : | : | : |
| : | : | : |
| : | : | : |
+--------------------+----------+-------------------------+
Figure 7
Figure 7 shows MSLB table. MSLB have this table and translate the
destination address using this table value. MSLB-F check source IP
address, and translate destination address with this table.
Using IPv4-IPv6 translation may possible, i.e., IPv4 packet
translated to IPv6, then translate to IPv4 or IPv6 packet translate
to IPv4, then translate IPv6 may possibleFigure 8 shows possible
combination of IPv4 and IPv6. These IPv4-IPv6 translation case will
be defined in future.
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Client MSLB-F MSLB-B Server
: :
: :
(1) <-- IPv4 --> : <-- IPv4 --> : <-- IPv4 -->
: :
(2) <-- IPv6 --> : <-- IPv6 --> : <-- IPv6 -->
: :
(3) <-- IPv4 --> : <-- IPv6 --> : <-- IPv4 -->
: :
(4) <-- IPv6 --> : <-- IPv4 --> : <-- IPv6 -->
: :
Figure 8
5.2. encapsulation mode
This mode using encapsulation technique.
Figure Figure 9 shows packet processing with encapsulation mode.
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+-------+ +------+ +------+
| +---+MSLB-B+---+Server|
| | | IP_B1| | IP_S |
+-------+ +------+ | | +------+ +------+
| | | | | |
+------+ | | | | | | +------+ +------+
|Client|---+Network+---+MSLB-F|---+Network+---+MSLB-B+---+Server|
| IP_C | | | | | | | | IP_B2| | IP_S |
+------+ | | | IP_S | | | +------+ +------+
| | | | | |
+-------+ +------+ | | +------+ +------+
| +---+MSLB-B+---+Server|
| | | IP_B3| | IP_S |
+-------+ +------+ +------+
: :
: :
+------+----+ : +------+----+----+ :+------+----+
| data | IP | : | data | IP | IP | :| data | IP |
+------+----+ : +------+----+----+ :+------+----+
----------------------> : --------------------> : ------------>
src = IP_C : Inner header : src = IP_C
dst = IP_S : src = IP_C : dst = IP_S
: dst = IP_S :
: Outer header :
: src = IP_S :
: dst = IP_B1 :
: :
: :
: :
+------+----+ : +------+----+ :+------+----+
| data | IP | : | data | IP | :| data | IP |
+------+----+ : +------+----+ :+------+----+
<--------------------- -: <-------------------- : <------------
src = IP_S : src = IP_S : src = IP_S
dst = IP_C : dst = IP_C : dst = IP_C
: :
Figure 9
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In this figure, to the Client, IP address is allocated IP_C1, IP_C2,
and server IP address is IP_S. This case, IP_S is also allocate to
all servers and MSLB-F. And to the MSLB-B, IP_B1, IP_B2, IP_B3 is
allocated. These allocation is shown in upper part of Figure 6.
Lower part of Figure 6 shows packet transfered between client and
server. From Client to the Server, MSLB-F encapsulate original IP
packet and send to MSLB-B. MSLB-B decapsulate outer IP header, and
forwarad to the server. Inner IP packet does not change, that mean,
transparency is remained.
With encapsulation mode, packet size is increase, so fragmentation is
needed if encapsulated packet size exceed MTU or Path MTU. MSLB-F
MUST support tunnel MTU discovery [RFC1853]. Fragmentation and Path
MTU discovery [RFC1191] issue will describe in future.
Return packet, i.e., from server to the client is not encapsulate,
just forwarded.
In the Internet, Client IP address and server IP address must Global
IP address, however, IP address of MSLB-B may private IP address.
+--------------------+----------+-------------------------+
| Source IP address | net mask | destination IP address |
+--------------------+----------+-------------------------+
| IP_C1 | | IP_B1 |
+--------------------+----------+-------------------------+
| IP_C2 | | IP_B2 |
+--------------------+----------+-------------------------+
| : | : | : |
| : | : | : |
| : | : | : |
+--------------------+----------+-------------------------+
Figure 10
Figure 10 shows MSLB table. MSLB have this table and encapsulate and
generate outer header with destination address using this table
value. MSLB-F check source IP address, and generate destination
address of outer header with this table.
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Using IPv4 over IPv6 encapsulation or IPv6 over IPv4 encapsulation
may possible, i.e., IPv4 packet encapsulated to IPv6, then
decapsulate to IPv4 or IPv6 packet encapsulated to IPv4, then
deencapsulated IPv6 may possibleFigure 11 shows possible combination
of IPv4 and IPv6. These IPv4-IPv6 encapsulation case will be defined
in future.
Client MSLB-F MSLB-B Server
: :
: :
(1) <-- IPv4 --> : <-- IPv4 over IPv4 --> : <-- IPv4 -->
: :
(2) <-- IPv6 --> : <-- IPv6 over IPv6 --> : <-- IPv6 -->
: :
(3) <-- IPv4 --> : <-- IPv4 over IPv6 --> : <-- IPv4 -->
: :
(4) <-- IPv6 --> : <-- IPv6 over IPv4 --> : <-- IPv6 -->
: :
Figure 11
6. Ingress filtering environment
[RFC2827] describe ingress filtering for defending DoS attack which
employ IP source address spoofing.
Depend on the location of the MSLB-F and MSLB-B, it is possible that
packet from server to client is discarded by ingress filtering. In
such case, encapsulating the packet from server to client might
resolve. Figure 12 shows such solution.
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+-------+ +------+ +------+
| +---+MSLB-B+---+Server|
+------+ | | | IP_B1| | IP_S |
|Client| +-------+ +------+ | | +------+ +------+
| IP_C1+---+ | | | | |
+------+ | | | | | | +------+ +------+
|Network| |MSLB-F|---+Network+---+MSLB-B+---+Server|
| +---+ | | | | IP_B2| | IP_S |
+------+ | | | IP_S | | | +------+ +------+
|Client+---+ | | | | |
| IP_C2| +-------+ +------+ | | +------+ +------+
+------+ | +---+MSLB-B+---+Server|
| | | IP_B3| | IP_S |
+-------+ +------+ +------+
: :
+------+----+ : +------+----+----+ :+------+----+
| data | IP | : | data | IP | IP | :| data | IP |
+------+----+ : +------+----+----+ :+------+----+
<--------------------- -: <-------------------- : <------------
src = IP_S : Inner header : src = IP_S
dst = IP_C : src = IP_S : dst = IP_C
: dst = IP_C :
: Outer header :
: src = IP_B1
: dst = IP_TBD
Figure 12
7. Characteristic
MSLB has following characteristics.
* Layer 3 Load balancer
* Support NAT unfriendly application such as FTP
* work with any application layer protocol (maybe)
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* work with encription (IPsec ESP, SSL/TLS)
* work over Layer 3 network
* may enforce policy with static configuration
8. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
9. Security Considerations
Security consideration does not discussed in this memo.
10. Acknowledgements
11. Normative References
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990,
<https://www.rfc-editor.org/info/rfc1191>.
[RFC1546] Partridge, C., Mendez, T., and W. Milliken, "Host
Anycasting Service", RFC 1546, DOI 10.17487/RFC1546,
November 1993, <https://www.rfc-editor.org/info/rfc1546>.
[RFC1853] Simpson, W., "IP in IP Tunneling", RFC 1853,
DOI 10.17487/RFC1853, October 1995,
<https://www.rfc-editor.org/info/rfc1853>.
[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>.
[RFC2775] Carpenter, B., "Internet Transparency", RFC 2775,
DOI 10.17487/RFC2775, February 2000,
<https://www.rfc-editor.org/info/rfc2775>.
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[RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP Source
Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
May 2000, <https://www.rfc-editor.org/info/rfc2827>.
[RFC2993] Hain, T., "Architectural Implications of NAT", RFC 2993,
DOI 10.17487/RFC2993, November 2000,
<https://www.rfc-editor.org/info/rfc2993>.
Author's Address
Naoki Matsuhira
WIDE Project
Japan
Email: naoki.matsuhira@gmail.com
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