Network Working Group M. Smith
Internet Draft D. Dutt
Intended status: Experimental Cisco Systems
Expires: September 11, 2011 March 11, 2011
Layer 2 (L2) LISP Encapsulation Format
draft-smith-lisp-layer2-00.txt
Abstract
This memo describes an encapsulation method for carrying Ethernet
and IEEE 802 media access control (MAC) frames within the Locator/ID
Separation Protocol (LISP).
Status of this Memo
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Table of Contents
1. Introduction...................................................2
2. Conventions used in this document..............................2
3. Basic Overview.................................................3
4. L2 LISP Encapsulation Details..................................4
4.1. L2 LISP Header Format.....................................4
4.2. Header Field Descriptions.................................4
5. MTU Considerations.............................................5
6. Security Considerations........................................5
7. IANA Considerations............................................5
8. References.....................................................6
8.1. Normative References......................................6
8.2. Informative References....................................6
9. Acknowledgments................................................6
1. Introduction
LISP [LISP] specifies an architecture and method for separating the
location of an endpoint from its network identifier. It does this
by using two separate name spaces: EIDs representing the network
identifier of the endpoint and RLOCs representing the network
location of the endpoint. This document extends the LISP
specifications to allow Ethernet/IEEE 802 MAC frames to be carried
within the LISP frame. The MAC addresses of the encapsulated
Ethernet/IEEE 802 MAC frames will be used as EIDs.
2. 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].
In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance.
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3. Basic Overview
L2 LISP specifies the mechanism on which to carry L2 traffic over a
LISP network. Within an L2 LISP environment, the source and
destination MAC addresses of the Ethernet/IEEE 802.3 packet are used
as the source and destination EIDs. The RLOCs can use IPv4 or IPv6
addressing. The entire MAC frame is encapsulated with the exception
of the preamble and trailing FCS. It should be noted that L2 LISP
introduces the possibility of packet reordering during route
topology changes due to the usage of IP as the network substrate.
This memo addresses the data plane and frame format details of L2
LISP. The control plane details are outside the scope of this memo.
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4. L2 LISP Encapsulation Details
The L2 LISP encapsulation is based on the LISP header defined in the
LISP specification [LISP]. The UDP and LISP headers are shown below
for reference.
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ | Source Port = xxxx | Dest Port = 4341 |
UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ | UDP Length | UDP Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L |N|L|E|V|I|flags| Nonce/Map-Version |
I \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
S / | Instance ID/Locator Status Bits |
P +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
When the headers are used for encapsulating L2 frames, the following
settings are required:
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ | Source Port = xxxx | Dest Port = 8472 |
UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ | UDP Length | UDP Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L |0 0 0 0|I|0 0 0| Not Used |
I \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
S / | Instance ID | Not Used |
P +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The "Not Used" fields may be enabled in the future for usage in L2
LISP by allocating an unused bit in the flags field. This will be
defined within the main LISP specification [LISP].
4.1. Header Field Descriptions
UDP Header: The UDP header contains a ITR selected source port when
encapsulating a L2 LISP packet. The source port allows routers
and bridges in the network to load-split the traffic across the
equal cost paths available. The choice of the source port SHOULD
be made based on a hash of some combination of the inner frame
header fields such as but not limited to the source MAC address,
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destination MAC address, Length/Ethertype, and IP header fields
if present. The destination port MUST be set to the well-known
IANA assigned port value 8472.
UDP Length: The UDP length field is for an IPv4 encapsulated
packet, the length of the inner L2 frame plus the UDP and LISP
header lengths are used. For an IPv6 encapsulated packet, the
length of the inner L2 frame plus the size of the IPv6 header (40
bytes) plus the size of the UDP and LISP headers are used. The
UDP header length is 8 bytes.
UDP Checksum: The UDP checksum field is used in accordance with the
LISP specification [LISP].
I: The I bit is the Instance ID bit. When this bit is set to 1, it
indicates that the Instance ID field carried the LISP header is
valid. In L2 LISP, this bit MUST be set to 1.
Instance ID: An EID is scoped within the virtual L2 network which is
specified through the usage of the Instance ID field. The
Instance ID namespace is contained within a single administrative
domain. The 24-bit Instance ID field is used in accordance with
the LISP specification [LISP].
5. MTU Considerations
Since additional tunnel headers are prepended, the packet becomes
larger and can exceed the MTU of any link traversed from the ITR to
the ETR. It is recommended in IPv4 that packets do not get
fragmented as they are encapsulated by the ITR.
6. Security Considerations
Security in a network carrying L2 LISP should be similar to security
in a normal IPv4 network. Packet filtering on the L2 LISP inner
frames will require that a firewall look inside the L2 LISP packet
or that filtering is done at the ITR/ETR.
7. IANA Considerations
The IANA registry has allocated UDP port number 8472 for the L2 LISP
data packets.
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8. References
8.1. Normative References
[802.1Q] ANSI/IEEE Standard 802.1Q-2005, "IEEE Standards for Local
and Metropolitan Area Networks: Virtual Bridged Local Area
Networks", 2005.
[LISP] Farinacci, D., Fuller, V., Meyer, D., Lewis, D., draft-
ietf-lisp-10.txt (work in progress), March 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March, 1997.
8.2. Informative References
9. Acknowledgments
The authors would like to thank Dino Farinacci, Sumeet Singh, Ajit
Sanzgiri, and Larry Kreeger for their technical and editorial
commentary.
This document was prepared using 2-Word-v2.0.template.dot.
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Authors' Addresses
Michael Smith
Cisco Systems
Tasman Drive
San Jose, CA 95134
Email: michsmit@cisco.com
Dinesh Dutt
Cisco Systems
Tasman Drive
San Jose, CA 95134
Email: ddutt@cisco.com
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