Internet DRAFT - draft-yong-gre-in-udp-encap-4-service-chaining
draft-yong-gre-in-udp-encap-4-service-chaining
Network Working Group L. Yong
Internet Draft Huawei Technologies, USA
Category: Standard Track
Expires: January 2014 July 13, 2013
GRE-in-UDP Encapsulation for Service Chaining
draft-yong-gre-in-udp-encap-4-service-chaining-00.txt
Abstract
This document proposes use of the GRE-in-UDP encapsulation [GRE-in-
UDP] for the packet encapsulation in service chaining.
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Internet-Draft GRE-in-UDP Encap. for Service Chaining July 2013
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Table of Contents
1. Introduction...................................................3
1.1. Conventions used in this document.........................3
2. GRE-in-UDP Encapsulation for Service Chaining..................3
3. Procedures.....................................................5
4. Security Considerations........................................5
5. IANA Considerations............................................6
6. References.....................................................6
6.1. Normative References......................................6
6.2. Informative References....................................6
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1. Introduction
New Data Center and Cloud applications drive more flexible to deploy
the services including network services such as firewall and load
balancing, etc. To achieve that, the service chain technology is
necessary.[SC-PS] [NSC-PS] Service chain denotes a sequence of
service processes applying to flow packets before flow packets being
delivered to the destination. Service Chaining refers to the
mechanism of building service chains. [SC-REQ]
IP forwarding is based on the IP destination address on the packet.
Applying service chain technology in an IP network, the flow packets
need to be forward along the service chain path not the shortest
path. Therefore, directly forwarding on IP destination address on
packets will not work. Hop-by-hop tunneling the flow packets along a
service chain path is a way to address the issue. In addition, some
service information are necessary to be inserted on the flow
packets.[NSH]
This document proposes use of the GRE-in-UDP encapsulation [GRE-in-
UDP] for the packet encapsulation in the service chaining. The
encapsulation allows a network protocol to be tunneled over an IP
network. The payload type is identified in the protocol type field
in GRE header and the flow entropy may be encoded in the UDP source
port. The latter supports the network load balancing per flow basis.
The benefit of this encapsulation scheme is not burning UDP ports
for the payload identification and supports IP ECMP without changing
existing transit routers.
1.1. Conventions used in this document
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].
2. GRE-in-UDP Encapsulation for Service Chaining
Following figure illustrates the format of GRE-in-UDP encapsulation
for service chaining with IPv4 outer headers. The IP protocol is
filled with 17 (UDP). When the outer header is IPv6, the next header
field is encoded with 17 (UDP).
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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
IPv4 Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| IHL |Type of Service| Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identification |Flags| Fragment Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Time to Live |Protcol=17[UDP]| Header Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
UDP Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port = entropy | Dest Port = GRE-in-UDP |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UDP Length | UDP Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
GRE Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| |0|0| Reserved0 | Ver |Proto Type=Service Chain (TBD) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Server Chain Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Chain Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Chain Data (Variable) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Original Payload:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Original Payload ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1 The format for Service Chaining Encapsulation
In this encapsulation format, the UDP source port is for flow
entropy. The value can be derived from the original payload header;
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the UDP destination port has a registered port value for GRE-in-UDP.
The protocol type field in GRE header is used to indicate tunneled
protocol type. To support Service Chaining application, the document
proposes allocating a new protocol type for Service Chaining. In
addition, for this application, the bits for checksum, key present,
and sequence in GRE header MUST be clear. The usages of other fields
in udp and gre headers MUST comply with the specification in the
GRE-in-UDP document [GRE-in-UDP].
Service header and data are inserted at the front of the original
payload before adding gre-in-ugp encapsulation. The original payload
may be an IP, Ethernet, MPLS, etc.
3. Procedures
When the first service node in the service chain such as service
classifier receives a packet and needs to send it to the next
service node, it inserts the service data and service header on the
packet first, performs the gre-in-udp encapsulation with the Service
Chaining protocol type, and then adds IP header on the packet with
the next service node IP address as the destination IP address and
its IP address as the source IP address.
When a transit service node in the service chain receives a packet,
it decapsulates the packet and performs the service. When it needs
to forward the packet to next service node, it performs the gre-in-
udp encapsulation and adds IP outer header before sending the packet
out. Note that, the transit service node may modify the service
header and/or data on the packet.
When the last service node in the service chain completes the
service process on a packet, it removes the service header and data,
and forwards the original payload directly.
The gre-in-udp encapsulation process MUST comply with the procedures
specified in the GRE-in-UDP Encapsulation document [GRE-in-UDP].
4. Security Considerations
Coming soon.
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5. IANA Considerations
Request to allocate a protocol type value for Service Chaining.
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC2119, March 1997.
6.2. Informative References
[GRE-in-UDP] Crabbe, E. Yong, L., and Xu, X. "Generic UDP
Encapsulation for IP Tunneling", draft-yong-tsvwg-gre-in-
udp-encap-01, work in progress.
[NHS] Quinn, P., et al, "Network Service Header", draft-quinn-nsh-
01.txt, work in progress.
[NSC-PS] Guichard, J., et al, "Network Service Chaining Problem
Statement", draft-quinn-nsc-problem-statement-00.txt, work
in progress.
[SC-PS] Dunbar, L. and Eastlake, D., "Layer 4-7 Service Chain
problem statement", draft-dunbar-l4-l7-sc-problem-
statement-00.txt, work in progress.
[SC-REQ] Li, H. and Jiang Y., "Requirements for Service Chaining",
draft-li-service-chaining-requirements-00 , work in
progress.
Authors' Addresses
Lucy Yong
Huawei Technologies
5340 Legacy Drive
Plano, TX 75025
U.S.A
Phone: 469-277-5837
Email: lucy.yong@huawei.com
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