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IETF RFC 4338
Transmission of IPv6, IPv4, and Address Resolution Protocol (ARP) Packets over Fibre Channel
Last modified on Monday, January 23rd, 2006
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Network Working Group C. DeSanti
Request for Comments: 4338 Cisco Systems
Obsoletes: 3831, 2625 C. Carlson
Category: Standards Track QLogic Corporation
R. Nixon
Emulex
January 2006
Transmission of IPv6, IPv4, and
Address Resolution Protocol (ARP) Packets over Fibre Channel
 Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright © The Internet Society (2006).
Abstract
This document specifies the way of encapsulating IPv6, IPv4, and
Address Resolution Protocol (ARP) packets over Fibre Channel. This
document also specifies the method of forming IPv6 link-local
addresses and statelessly autoconfigured IPv6 addresses on Fibre
Channel networks, and a mechanism to perform IPv4 address resolution
over Fibre Channel networks.
This document obsoletes RFC 2625 and RFC 3831.
DeSanti, et al. Standards Track PAGE 1 
RFC 4338 IP over Fibre Channel January 2006
Table of Contents
1. Introduction ....................................................3
2. Summary of Fibre Channel ........................................4
2.1. Overview ...................................................4
2.2. Identifiers and Login ......................................5
2.3. FC Levels and Frame Format .................................5
2.4. Sequences and Exchanges ....................................6
3. IP-capable Nx_Ports .............................................7
4. IPv6, IPv4, and ARP Encapsulation ...............................7
4.1. FC Sequence Format for IPv6 and IPv4 Packets ...............7
4.2. FC Sequence Format for ARP Packets .........................9
4.3. FC Classes of Service .....................................10
4.4. FC Header Code Points .....................................10
4.5. FC Network_Header .........................................11
4.6. LLC/SNAP Header ...........................................12
4.7. Bit and Byte Ordering .....................................12
4.8. Maximum Transfer Unit .....................................12
5. IPv6 Stateless Address Autoconfiguration .......................13
5.1. IPv6 Interface Identifier and Address Prefix ..............13
5.2. Generating an Interface ID from a Format 1 N_Port_Name ....14
5.3. Generating an Interface ID from a Format 2 N_Port_Name ....15
5.4. Generating an Interface ID from a Format 5 N_Port_Name ....16
5.5. Generating an Interface ID from an EUI-64 Mapped
N_Port_Name ...............................................17
6. Link-local Addresses ...........................................18
7. ARP Packet Format ..............................................18
8. Link-layer Address/Hardware Address ............................20
9. Address Mapping for Unicast ....................................20
9.1. Overview ..................................................20
9.2. IPv6 Address Mapping ......................................20
9.3. IPv4 Address Mapping ......................................21
10. Address Mapping for Multicast .................................22
11. Sequence Management ...........................................23
12. Exchange Management ...........................................23
13. Interoperability with RFC 2625 ................................24
14. Security Considerations .......................................25
15. IANA Considerations ...........................................25
16. Acknowledgements ..............................................25
17. Normative References ..........................................26
18. Informative References ........................................26
A. Transmission of a Broadcast FC Sequence over FC Topologies
(Informative) ..................................................28
B. Validation of the <N_Port_Name, N_Port_ID> Mapping
(Informative) ..................................................29
C. Fibre Channel Bit and Byte Numbering Guidance ..................30
D. Changes from RFC 2625 ..........................................31
E. Changes from RFC 3831 ..........................................31
DeSanti, et al. Standards Track PAGE 2
RFC 4338 IP over Fibre Channel January 2006
1. Introduction
Fibre Channel (FC) is a high-speed serial interface technology that
supports several Upper Layer Protocols including Small Computer
System Interface (SCSI), IPv6 [IPv6], and IPv4 [IPv4].
[RFC 2625] defined how to encapsulate IPv4 and Address Resolution
Protocol (ARP) packets over Fibre Channel for a subset of Fibre
Channel devices. This specification enables the support of IPv4 for
a broader category of Fibre Channel devices. In addition, this
specification simplifies [RFC 2625] by removing unused options and
clarifying current implementations. This document obsoletes
[RFC 2625].
Specific [RFC 2625] limitations that this document aims to resolve
are the following:
- N_Port_Name format restriction. [RFC 2625] restricts the use of
IPv4 to Fibre Channel devices having the format 0x1 N_Port_Name,
but many current implementations use other N_Port_Name formats.
- Use of Fibre Channel Address Resolution Protocol (FARP).
[RFC 2625] requires the support of FARP to map N_Port_Names to
N_Port_IDs, but many current implementations use other methods,
such as the Fibre Channel Name Server.
- Missing support for IPv4 multicast. [RFC 2625] does not specify
how to transmit IPv4 packets with a multicast destination address
over Fibre Channel.
[RFC 3831] defines how to encapsulate IPv6 over Fibre Channel and a
method of forming IPv6 link-local addresses [AARCH] and statelessly
autoconfigured IPv6 addresses on Fibre Channel networks. [RFC 3831]
also describes the content of the Source/Target Link-layer Address
option used in Neighbor Discovery [DISC] when the messages are
transmitted on a Fibre Channel network. This document obsoletes
[RFC 3831].
Warning to readers familiar with Fibre Channel: both Fibre Channel
and IETF standards use the same byte transmission order. However,
the bit numbering is different. See Appendix C for guidance.
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 [KEYWORDS].
DeSanti, et al. Standards Track PAGE 3
RFC 4338 IP over Fibre Channel January 2006
2. Summary of Fibre Channel
2.1. Overview
Fibre Channel (FC) is a gigabit-speed network technology primarily
used for storage networking. Fibre Channel is standardized in the
T11 Technical Committee of the InterNational Committee for
Information Technology Standards (INCITS), an American National
Standard Institute (ANSI) accredited standards committee.
Fibre Channel devices are called Nodes. Each Node has one or more
Ports that connect to Ports of other devices. Fibre Channel may be
implemented using any combination of the following three topologies:
- a point-to-point link between two Ports;
- a set of Ports interconnected by a switching network called a
Fabric, as defined in [FC-FS];
- a set of Ports interconnected with a loop topology, as defined in
[FC-AL-2].
A Node Port that does not operate in a loop topology is called an
N_Port. A Node Port that operates in a loop topology using the
loop-specific protocols is designated as an NL_Port. The term
Nx_Port is used to indicate a Node Port that is capable of operating
in either mode.
A Fabric Port that does not operate in a loop topology is called an
F_Port. A Fabric Port that operates in a loop topology using the
loop-specific protocols is designated as an FL_Port. The term
Fx_Port is used to indicate a Fabric Port that is capable of
operating in either mode.
A Fibre Channel network, built with any combination of the FC
topologies described above, is a multiaccess network with broadcast
capabilities.
From an IPv6 point of view, a Fibre Channel network is an IPv6 Link
[IPv6]. IP-capable Nx_Ports are what [IPv6] calls Interfaces.
From an IPv4 point of view, a Fibre Channel network is an IPv4 Local
Network [IPv4]. IP-capable Nx_Ports are what [IPv4] calls Local
Network Interfaces.
DeSanti, et al. Standards Track PAGE 4
RFC 4338 IP over Fibre Channel January 2006
2.2. Identifiers and Login
Fibre Channel entities are identified by non-volatile 64-bit
Name_Identifiers. [FC-FS] defines several formats of
Name_Identifiers. The value of the most significant 4 bits defines
the format of a Name_Identifier. These Name_Identifiers are referred
to in a more concise manner as follows:
- an Nx_Port's Name_Identifier is called N_Port_Name;
- an Fx_Port's Name_Identifier is called F_Port_Name;
- a Node's Name_Identifier is called Node_Name;
- a Fabric's Name_Identifier is called Fabric_Name.
An Nx_Port connected to a Fibre Channel network is associated with
two identifiers, its non-volatile N_Port_Name and a volatile 24-bit
address called N_Port_ID. The N_Port_Name is used to identify the
Nx_Port, and the N_Port_ID is used for communications among Nx_Ports.
Each Nx_Port acquires an N_Port_ID from the Fabric by performing a
process called Fabric Login, or FLOGI. The FLOGI process is used
also to negotiate several communications parameters between the
Nx_Port and the Fabric, such as the receive data field size, which
determines the maximum size of the Fibre Channel frames that may be
transferred between the Nx_Port and the Fabric.
Before effective communication may take place between two Nx_Ports,
they must complete a process called Port Login, or PLOGI. The PLOGI
process provides each Nx_Port with the other Nx_Port's N_Port_Name,
and negotiates several communication parameters, such as the receive
data field size, which determines the maximum size of the Fibre
Channel frames that may be transferred between the two Nx_Ports.
Both Fabric Login and Port Login may be explicit (i.e., performed
using specific FC control messages called Extended Link Services, or
ELSes) or implicit (i.e., in which the parameters are specified by
configuration or other methods).
2.3. FC Levels and Frame Format
[FC-FS] describes the Fibre Channel protocol using 5 different
levels. The FC-2 and FC-4 levels are relevant for this
specification. The FC-2 level defines the FC frame format, the
transport services, and the control functions necessary for
information transfer. The FC-4 level supports Upper Level Protocols,
such as IPv6, IPv4, and SCSI. The Fibre Channel frame format is
shown in figure 1.
DeSanti, et al. Standards Track PAGE 5
RFC 4338 IP over Fibre Channel January 2006
+-----+-----------+-----------+--------//-------+-----+-----+
| | | Data Field | | |
| SOF | FC Header |<--------------------------->| CRC | EOF |
| | | Optional | Frame | | |
| | | Header(s) | Payload | | |
+-----+-----------+-----------+--------//-------+-----+-----+
Figure 1: Fibre Channel Frame Format
The Start of Frame (SOF) and End of Frame (EOF) are special FC
transmission words that act as frame delimiters. The Cyclic
Redundancy Check (CRC) is 4 octets long and is used to verify the
integrity of a frame.
The FC Header is 24 octets long and contains several fields
associated with the identification and control of the Data Field.
The Data Field is of variable size, ranging from 0 to 2112 octets,
and includes the user data in the Frame Payload field and Optional
Headers. The currently defined Optional Headers are the following:
- ESP_Header;
- Network_Header;
- Association_Header;
- Device_Header.
The value of the SOF field determines the FC Class of service
associated with the frame. Five Classes of service are specified in
[FC-FS]. They are distinguished primarily by the method of flow
control between the communicating Nx_Ports and by the level of data
integrity provided. A given Fabric or Nx_Port may support one or
more of the following Classes of service:
- Class 1: Dedicated physical connection with delivery confirmation;
- Class 2: Frame multiplexed service with delivery confirmation;
- Class 3: Datagram service;
- Class 4: Fractional bandwidth;
- Class 6: Reliable multicast via dedicated connections.
Classes 3 and 2 are commonly used for storage networking
applications; Classes 1 and 6 are typically used for specialized
applications in avionics. Class 3 is recommended for IPv6, IPv4, and
ARP (see section 4.3).
2.4. Sequences and Exchanges
An application-level payload such as an IPv6 or IPv4 packet is called
an Information Unit at the FC-4 level of Fibre Channel. Each FC-4
DeSanti, et al. Standards Track PAGE 6
RFC 4338 IP over Fibre Channel January 2006
Information Unit is mapped to an FC Sequence by the FC-2 level. An
FC Sequence consists of one or more FC frames related by the value of
the Sequence_ID (SEQ_ID) field of the FC Header.
The architectural maximum data that may be carried by an FC frame is
2112 octets. The maximum usable frame size depends on the Fabric and
Nx_Port implementations and is negotiated during the Login process.
Whenever an Information Unit to be transmitted exceeds this value,
the FC-2 level segments it into multiple FC frames, sent as a single
Sequence. The receiving Nx_Port reassembles the Sequence of frames
and delivers a reassembled Information Unit to the FC-4 level. The
Sequence Count (SEQ_CNT) field of the FC Header may be used to ensure
frame ordering.
Multiple Sequences may be grouped together as belonging to the same
FC Exchange. The Exchange is a mechanism used by two Nx_Ports to
identify and manage an operation between them. The Exchange is
opened when the operation is started between the two Nx_Ports, and
closed when the operation ends. FC frames belonging to the same
Exchange are related by the value of the Exchange_ID fields in the FC
Header. An Originator Exchange_ID (OX_ID) and a Responder
Exchange_ID (RX_ID) uniquely identify the Exchange between a pair of
Nx_Ports.
3. IP-capable Nx_Ports
This specification requires an IP-capable Nx_Port to have the
following properties:
- The format of its N_Port_Name MUST be one of 0x1, 0x2, 0x5, 0xC,
0xD, 0xE, 0xF (see section 5.1);
- It MUST support Class 3;
- It MUST support continuously increasing SEQ_CNT [FC-FS];
- It MUST be able to transmit and receive an FC-4 Information Unit
at least 1304 octets long (see section 4.1);
- It SHOULD support a receive data field size for Device_Data FC
frames of at least 1024 octets (see section 10).
4. IPv6, IPv4, and ARP Encapsulation
4.1. FC Sequence Format for IPv6 and IPv4 Packets
An IPv6 or IPv4 packet is mapped to an Information Unit at the FC-4
level of Fibre Channel, which in turn is mapped to an FC Sequence by
the FC-2 level [FC-FS]. An FC Information Unit containing an IP
packet MUST carry the FC Network_Header [FC-FS] and the Logical Link
Control/SubNetwork Access Protocol (LLC/SNAP) header [IEEE-LLC],
resulting in the FC Information Unit format shown in figure 2.
DeSanti, et al. Standards Track PAGE 7
RFC 4338 IP over Fibre Channel January 2006
+---------------+---------------+---------------+---------------+
| |
+- -+
| Network_Header |
+- (16 octets) -+
| |
+- -+
| |
+---------------+---------------+---------------+---------------+
| LLC/SNAP header |
+- (8 octets) -+
| |
+---------------+---------------+---------------+---------------+
| |
+- -+
/ IPv6 or IPv4 Packet /
/ /
+- -+
| |
+---------------+---------------+---------------+---------------+
Figure 2: FC Information Unit Mapping an IP Packet
In order to support the minimum IPv6 MTU (i.e., 1280 octets), an
Nx_Port supporting IP MUST be able to transmit and receive an FC-4
Information Unit at least 1304 octets long (i.e., 1280 + 8 + 16).
The FC ESP_Header [FC-FS] MAY be used to secure the FC frames
composing an IP FC Sequence. Other FC Optional Headers MUST NOT be
used in an IP FC Sequence.
An IP FC Sequence often consists of more than one frame, all frames
having the same TYPE (see section 4.4). The first frame of the
Sequence MUST include the FC Network_Header and the LLC/SNAP header.
The other frames MUST NOT include them, as shown in figure 3.
First Frame of an IP FC Sequence
+-----------+-------------------+-----------------+-------//--------+
| FC Header | FC Network_Header | LLC/SNAP header | First chunk of |
| | | | the IP Packet |
+-----------+-------------------+-----------------+-------//--------+
Subsequent Frames of an IP FC Sequence
+-----------+-----------------//--------------------+
| FC Header | Additional chunk of the IP Packet |
+-----------+----------------//---------------------+
Figure 3: Optional Headers in an IP FC Sequence
DeSanti, et al. Standards Track PAGE 8
RFC 4338 IP over Fibre Channel January 2006
4.2. FC Sequence Format for ARP Packets
An ARP packet is mapped to an Information Unit at the FC-4 level of
Fibre Channel, which in turn is mapped to an FC Sequence by the FC-2
level. An FC Information Unit containing an ARP packet MUST carry
the FC Network_Header [FC-FS] and the LLC/SNAP header [IEEE-LLC],
resulting in the FC Information Unit format shown in figure 4.
+---------------+---------------+---------------+---------------+
| |
+- -+
| Network_Header |
+- (16 octets) -+
| |
+- -+
| |
+---------------+---------------+---------------+---------------+
| LLC/SNAP header |
+- (8 octets) -+
| |
+---------------+---------------+---------------+---------------+
| |
+- -+
/ ARP Packet /
/ /
+- -+
| |
+---------------+---------------+---------------+---------------+
Figure 4: FC Information Unit Mapping an ARP Packet
Given the limited size of an ARP packet (see section 7), an FC
Sequence carrying an ARP packet MUST be mapped to a single FC frame
that MUST include the FC Network_Header and the LLC/SNAP header.
The FC ESP_Header [FC-FS] MAY be used to secure an FC frame carrying
an ARP packet. Other FC Optional Headers MUST NOT be used in an FC
frame carrying an ARP packet.
DeSanti, et al. Standards Track PAGE 9
RFC 4338 IP over Fibre Channel January 2006
4.3. FC Classes of Service
This specification uses FC Class 3. The following types of packets
MUST be mapped in Class 3 FC frames:
- multicast IPv6 packets;
- multicast/broadcast IPv4 packets;
- Control Protocol packets (e.g., ARP packets; IPv6 packets carrying
ICMPv6 [ICMPv6], Neighbor Discovery [DISC], or Multicast Listener
Discovery [MLDv2] messages; IPv4 packets carrying ICMP [ICMPv4] or
IGMP [IGMPv3] messages; IPv6 and IPv4 Routing Protocols packets).
Other IPv6 and IPv4 packets (i.e., unicast IP packets carrying data
traffic) SHOULD be mapped in Class 3 FC frames as well. Support for
reception of IPv4 or IPv6 packets mapped in FC frames of any Class
other than Class 3 is OPTIONAL; receivers MAY ignore them.
4.4. FC Header Code Points
The fields of the Fibre Channel Header are shown in figure 5. The
D_ID and S_ID fields contain, respectively, the destination N_Port_ID
and the source N_Port_ID.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| R_CTL | D_ID |
+---------------+---------------+---------------+---------------+
| CS_CTL/Prio | S_ID |
+---------------+---------------+---------------+---------------+
| TYPE | F_CTL |
+---------------+---------------+---------------+---------------+
| SEQ_ID | DF_CTL | SEQ_CNT |
+---------------+---------------+---------------+---------------+
| OX_ID | RX_ID |
+---------------+---------------+---------------+---------------+
| Parameter |
+---------------+---------------+---------------+---------------+
Figure 5: FC Header Format
To encapsulate IPv6 and IPv4 over Fibre Channel, the following code
points apply. When a single value is listed without further
qualification, that value MUST be used:
- R_CTL: 0x04 (Device_Data frame with Unsolicited Data Information
Category [FC-FS]);
- TYPE: 0x05 (IP over Fibre Channel);
DeSanti, et al. Standards Track PAGE 10
RFC 4338 IP over Fibre Channel January 2006
- CS_CTL/Prio: 0x00 is the default, see [FC-FS] for other values;
- DF_CTL: 0x20 (Network_Header) for the first FC frame of an IPv6 or
IPv4 Sequence, 0x00 for the following FC frames. If the FC
ESP_Header is used, then 0x60 for the first FC frame of an IPv6 or
IPv4 Sequence, 0x40 for the following FC frames;
- F_CTL, SEQ_ID, SEQ_CNT, OX_ID, RX_ID: see section 11, section 12,
and [FC-FS] for additional requirements;
- Parameter: if Relative Offset [FC-FS] is not used, the content of
this field MUST be ignored by the receiver, and SHOULD be set to
zero by the sender. If Relative Offset is used, see [FC-FS].
To encapsulate ARP over Fibre Channel, the following code points
apply. When a single value is listed without further qualification,
that value MUST be used:
- R_CTL: 0x04 (Device_Data frame with Unsolicited Data Information
Category [FC-FS]);
- TYPE: 0x05 (IP over Fibre Channel);
- CS_CTL/Prio: 0x00 is the default, see [FC-FS] for other values;
- DF_CTL: 0x20 (Network_Header). If the FC ESP_Header is used, then
0x60;
- F_CTL, SEQ_ID, SEQ_CNT, OX_ID, RX_ID: see section 11, section 12,
and [FC-FS] for additional requirements;
- Parameter: SHOULD be set to zero.
4.5. FC Network_Header
The fields of the FC Network_Header are shown in figure 6. For use
with IPv6, IPv4, and ARP, the N_Port_Names formats MUST be one of
0x1, 0x2, 0x5, 0xC, 0xD, 0xE, 0xF [FC-FS].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- Destination N_Port_Name -+
| |
+---------------------------------------------------------------+
| |
+- Source N_Port_Name -+
| |
+---------------------------------------------------------------+
Figure 6: FC Network_Header Format
DeSanti, et al. Standards Track PAGE 11
RFC 4338 IP over Fibre Channel January 2006
4.6. LLC/SNAP Header
The fields of the LLC/SNAP header [IEEE-LLC] are shown in figure 7.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DSAP | SSAP | CTRL | OUI |
+---------------+---------------+---------------+---------------+
| OUI | PID |
+---------------+---------------+---------------+---------------+
Figure 7: LLC/SNAP Header Format
To encapsulate IPv6, IPv4, and ARP over Fibre Channel, the following
code points MUST be used:
- DSAP: 0xAA;
- SSAP: 0xAA;
- CTRL: 0x03;
- OUI: 0x000000;
- PID: 0x86DD for IPv6, 0x0800 for IPv4, 0x0806 for ARP.
4.7. Bit and Byte Ordering
IPv6, IPv4, and ARP packets are mapped to the FC-4 level using the
big-endian byte ordering that corresponds to the standard network
byte order or canonical form.
4.8. Maximum Transfer Unit
The default MTU size for IPv6 packets over Fibre Channel is 65280
octets. Large IPv6 packets are mapped to a Sequence of FC frames
(see section 2.4). This size may be reduced by a Router
Advertisement [DISC] containing an MTU option that specifies a
smaller MTU, or by manual configuration of each Nx_Port. However, as
required by [IPv6], the MTU MUST NOT be lower than 1280 octets. If a
Router Advertisement received on an Nx_Port has an MTU option
specifying an MTU larger than 65280, or larger than a manually
configured value, that MTU option MAY be logged to system management
but MUST be otherwise ignored.
As the default MTU size far exceeds the message sizes typically used
in the Internet, an IPv6 over FC implementation SHOULD implement Path
MTU Discovery [PMTUD6], or at least maintain different MTU values for
on-link and off-link destinations.
DeSanti, et al. Standards Track PAGE 12
RFC 4338 IP over Fibre Channel January 2006
For correct operation of IPv6 in a routed environment, it is
critically important to configure an appropriate MTU option in Router
Advertisements.
For correct operation of IPv6 when mixed media (e.g., Ethernet and
Fibre Channel) are bridged together, the smallest MTU of all the
media must be advertised by routers in an MTU option. If there are
no routers present, this MTU must be manually configured in each node
that is connected to a medium with a default MTU larger than the
smallest MTU.
The default MTU size for IPv4 packets over Fibre Channel is 65280
octets. Large IPv4 packets are mapped to a Sequence of FC frames
(see section 2.4). This size may be reduced by manual configuration
of each Nx_Port or by the Path MTU Discovery technique [PMTUD4].
5. IPv6 Stateless Address Autoconfiguration
5.1. IPv6 Interface Identifier and Address Prefix
The IPv6 Interface ID [AARCH] for an Nx_Port is based on the EUI-64
address [EUI64] derived from the Nx_Port's N_Port_Name. The IPv6
Interface Identifier is obtained by complementing the Universal/Local
(U/L) bit of the OUI field of the derived EUI-64 address. The U/L
bit has no function in Fibre Channel; however, it has to be properly
handled when a Name_Identifier is converted to an EUI-64 address.
[FC-FS] specifies a method to map format 0x1 (IEEE 48-bit address),
0x2 (IEEE Extended), or 0x5 (IEEE Registered) FC Name_Identifiers in
EUI-64 addresses. This allows the usage of these Name_Identifiers to
support IPv6. [FC-FS] also defines EUI-64 mapped FC Name_Identifiers
(formats 0xC, 0xD, 0xE, and 0xF) that are derived from an EUI-64
address. It is possible to reverse this address mapping to obtain
the original EUI-64 address in order to support IPv6.
IPv6 stateless address autoconfiguration MUST be performed as
specified in [ACONF]. An IPv6 Address Prefix used for stateless
address autoconfiguration of an Nx_Port MUST have a length of 64
bits.
DeSanti, et al. Standards Track PAGE 13
RFC 4338 IP over Fibre Channel January 2006
5.2. Generating an Interface ID from a Format 1 N_Port_Name
The Name_Identifier format 0x1 is shown in figure 8.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1| 0x000 | OUI |
+-------+-------+---------------+---------------+---------------+
| OUI | VSID |
+---------------+---------------+---------------+---------------+
Figure 8: Format 0x1 Name_Identifier
The EUI-64 address derived from this Name_Identifier has the format
shown in figure 9 [FC-FS].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OUI with complemented U/L bit |0 0 0 1| VSID |
+---------------+---------------+-------+-------+-------+-------+
| VSID | 0x000 |
+---------------+---------------+-------+-------+---------------+
Figure 9: EUI-64 Address from a Format 0x1 Name_Identifier
The IPv6 Interface Identifier is obtained from this EUI-64 address by
complementing the U/L bit in the OUI field. Therefore, the OUI in
the IPv6 Interface ID is exactly as in the FC Name_Identifier. The
resulting IPv6 Interface Identifier has local scope [AARCH] and the
format shown in figure 10.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OUI |0 0 0 1| VSID |
+---------------+---------------+-------+-------+-------+-------+
| VSID | 0x000 |
+---------------+---------------+-------+-------+---------------+
Figure 10: IPv6 Interface ID from a Format 0x1 Name_Identifier
As an example, the FC Name_Identifier 0x10-00-34-63-46-AB-CD-EF
generates the IPv6 Interface Identifier 3463:461A:BCDE:F000.
DeSanti, et al. Standards Track PAGE 14
RFC 4338 IP over Fibre Channel January 2006
5.3. Generating an Interface ID from a Format 2 N_Port_Name
The Name_Identifier format 0x2 is shown in figure 11.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 1 0| Vendor Specific | OUI |
+-------+-------+---------------+---------------+---------------+
| OUI | VSID |
+---------------+---------------+---------------+---------------+
Figure 11: Format 0x2 Name_Identifier
The EUI-64 address derived from this Name_Identifier has the format
shown in figure 12 [FC-FS].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OUI with complemented U/L bit |0 0 1 0| VSID |
+---------------+-----------------------+-------+-------+-------+
| VSID | Vendor Specific |
+---------------+-----------------------+-------+---------------+
Figure 12: EUI-64 Address from a Format 0x2 Name_Identifier
The IPv6 Interface Identifier is obtained from this EUI-64 address by
complementing the U/L bit in the OUI field. Therefore, the OUI in
the IPv6 Interface ID is exactly as in the FC Name_Identifier. The
resulting IPv6 Interface Identifier has local scope [AARCH] and the
format shown in figure 13.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OUI |0 0 1 0| VSID |
+---------------+-----------------------+-------+-------+-------+
| VSID | Vendor Specific |
+---------------+-----------------------+-------+---------------+
Figure 13: IPv6 Interface ID from a Format 0x2 Name_Identifier
As an example, the FC Name_Identifier 0x27-89-34-63-46-AB-CD-EF
generates the IPv6 Interface Identifier 3463:462A:BCDE:F789.
DeSanti, et al. Standards Track PAGE 15
RFC 4338 IP over Fibre Channel January 2006
5.4. Generating an Interface ID from a Format 5 N_Port_Name
The Name_Identifier format 0x5 is shown in figure 14.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 0 1| OUI | VSID |
+-------+-------+---------------+---------------+-------+-------+
| VSID |
+---------------+---------------+---------------+---------------+
Figure 14: Format 0x5 Name_Identifier
The EUI-64 address derived from this Name_Identifier has the format
shown in figure 15 [FC-FS].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OUI with complemented U/L bit |0 1 0 1| VSID |
+---------------+---------------+---------------+-------+-------+
| VSID |
+---------------+---------------+---------------+---------------+
Figure 15: EUI-64 Address from a Format 0x5 Name_Identifier
The IPv6 Interface Identifier is obtained from this EUI-64 address
complementing the U/L bit in the OUI field. Therefore, the OUI in
the IPv6 Interface ID is exactly as in the FC Name_Identifier. The
resulting IPv6 Interface Identifier has local scope [AARCH] and the
format shown in figure 16.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OUI |0 1 0 1| VSID |
+---------------+---------------+---------------+-------+-------+
| VSID |
+---------------+---------------+---------------+---------------+
Figure 16: IPv6 Interface ID from a Format 0x5 Name_Identifier
As an example, the FC Name_Identifier 0x53-46-34-6A-BC-DE-F7-89
generates the IPv6 Interface Identifier 3463:465A:BCDE:F789.
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RFC 4338 IP over Fibre Channel January 2006
5.5. Generating an Interface ID from an EUI-64 Mapped N_Port_Name
The EUI-64 mapped Name_Identifiers formats (formats 0xC through 0xF)
are derived from an EUI-64 address by compressing the OUI field of
such addresses. The compression is performed by removing the
Universal/Local and Individual/Group bits from the OUI, and by
putting bits 0 to 5 of the OUI in the first octet of the
Name_Identifier, and bits 8 to 23 of the OUI in the second and third
octet of the Name_Identifier, as shown in figure 17.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 1| OUI[0..5] | OUI[8..23] | VSID |
+---+-----------+---------------+---------------+---------------+
| VSID |
+---------------+---------------+---------------+---------------+
Figure 17: EUI-64 Mapped Name_Identifiers Format
The EUI-64 address used to generate the Name_Identifier shown in
figure 17 has the format shown in figure 18.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OUI[0..5] |0 0| OUI[8..23] | VSID |
+-----------+---+---------------+---------------+---------------+
| VSID |
+---------------+---------------+---------------+---------------+
Figure 18: EUI-64 Address from an EUI-64 Mapped Name_Identifier
The IPv6 Interface Identifier is obtained from this EUI-64 address by
complementing the U/L bit in the OUI field. The resulting IPv6
Interface Identifier has global scope [AARCH] and the format shown in
figure 19.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OUI[0..5] |1 0| OUI[8..23] | VSID |
+-----------+---+---------------+---------------+---------------+
| VSID |
+---------------+---------------+---------------+---------------+
Figure 19: IPv6 Interface ID from an EUI-64 Mapped Name_Identifier
DeSanti, et al. Standards Track PAGE 17
RFC 4338 IP over Fibre Channel January 2006
As an example, the FC Name_Identifier 0xCD-63-46-AB-01-25-78-9A
generates the IPv6 Interface Identifier 3663:46AB:0125:789A.
6. Link-local Addresses
The IPv6 link-local address [AARCH] for an Nx_Port is formed by
appending the Interface Identifier (as defined in section 5) to the
prefix FE80::/64. The resulting address is shown in figure 20.
10 bits 54 bits 64 bits
+----------+-----------------------+----------------------------+
|1111111010| (zeros) | Interface Identifier |
+----------+-----------------------+----------------------------+
Figure 20: IPv6 Link-local Address Format
7. ARP Packet Format
The Address Resolution Protocol defined in [ARP] is designed to be a
general purpose protocol, to accommodate many network technologies
and many Upper Layer Protocols.
[RFC 2625] chose to use for Fibre Channel the same ARP packet format
used for Ethernet networks. In order to do that, [RFC 2625]
restricted the use of IPv4 to Nx_Ports having N_Port_Name format 0x1.
Although this may have been a reasonable choice at that time, today
there are Nx_Ports with an N_Port_Name format other than 0x1 in
widespread use.
This specification accommodates Nx_Ports with N_Port_Names of a
format different from 0x1 by defining a Fibre Channel specific
version of the ARP protocol (FC ARP), carrying both N_Port_Name and
N_Port_ID as Hardware (HW) Address.
IANA has registered the number 18 (decimal) to identify Fibre Channel
as ARP HW type. The FC ARP packet format is shown in figure 21. The
length of the FC ARP packet is 40 octets.
DeSanti, et al. Standards Track PAGE 18
RFC 4338 IP over Fibre Channel January 2006
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HW Type = 0x0012 | Protocol = 0x0800 |
+---------------+---------------+---------------+---------------+
| HW Len = 12 | Proto Len = 4 | Opcode |
+---------------+---------------+---------------+---------------+
| |
+- -+
| HW Address of Sender |
+- -+
| |
+---------------+---------------+---------------+---------------+
| Protocol Address of Sender |
+---------------+---------------+---------------+---------------+
| |
+- -+
| HW Address of Target |
+- -+
| |
+---------------+---------------+---------------+---------------+
| Protocol Address of Target |
+---------------+---------------+---------------+---------------+
Figure 21: FC ARP Packet Format
The following code points MUST be used with FC ARP:
- HW Type: 0x0012 (Fibre Channel);
- Protocol: 0x0800 (IPv4);
- HW Len: 12 (Length in octets of the HW Address);
- Proto Len: 4 (Length in octets of the Protocol Address);
- Opcode: 0x0001 for ARP Request, 0x0002 for ARP Reply [ARP];
- HW Address of Sender: the HW Address (see section 8) of the
Requester in an ARP Request, or the HW Address of the Responder in
an ARP Reply;
- Protocol Address of Sender: the IPv4 address of the Requester in
an ARP Request, or that of the Responder in an ARP Reply;
- HW Address of Target: set to zero in an ARP Request, and to the HW
Address (see section 8) of the Requester in an ARP Reply;
- Protocol Address of Target: the IPv4 address of the Responder in
an ARP Request, or that of the Requester in an ARP Reply.
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RFC 4338 IP over Fibre Channel January 2006
8. Link-layer Address/Hardware Address
The Link-layer Address used in the Source/Target Link-layer Address
option (see section 9.2) and the Hardware Address used in FC ARP (see
section 7) have the same format, shown in figure 22.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- N_Port_Name -+
| |
+---------------+---------------+---------------+---------------+
| Reserved | N_Port_ID |
+---------------+---------------+---------------+---------------+
Figure 22: Link-layer Address/HW Address Format
Reserved fields MUST be set to zero when transmitting, and MUST be
ignored when receiving.
9. Address Mapping for Unicast
9.1. Overview
An Nx_Port has two kinds of Fibre Channel addresses:
- a non-volatile 64-bit address, called N_Port_Name;
- a volatile 24-bit address, called N_Port_ID.
The N_Port_Name is used to uniquely identify the Nx_Port, and the
N_Port_ID is used to route frames to the Nx_Port. Both FC addresses
are required to resolve an IPv6 or IPv4 unicast address. The fact
that the N_Port_ID is volatile implies that an Nx_Port MUST validate
the mapping between its N_Port_Name and N_Port_ID when certain Fibre
Channel events occur (see Appendix B).
9.2. IPv6 Address Mapping
The procedure for mapping IPv6 unicast addresses into Fibre Channel
link-layer addresses uses the Neighbor Discovery Protocol [DISC].
The Source/Target Link-layer Address option has the format shown in
figure 23 when the link layer is Fibre Channel.
DeSanti, et al. Standards Track PAGE 20
RFC 4338 IP over Fibre Channel January 2006
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length = 2 | |
+---------------+---------------+ -+
| |
+- Link-layer Address -+
| |
+- +---------------+---------------+
| | Padding |
+---------------+---------------+---------------+---------------+
Figure 23: Source/Target Link-layer Address Option for Fibre Channel
Type: 1 for Source Link-layer address.
2 for Target Link-layer address.
Length: 2 (in units of 8 octets).
Padding: MUST be set to zero when transmitting,
MUST be ignored when receiving.
Link-layer Address: the Nx_Port's Link-layer Address (see section
8).
9.3. IPv4 Address Mapping
The procedure for mapping IPv4 unicast addresses into Fibre Channel
link-layer addresses uses the FC ARP protocol, as specified in
section 7 and [ARP]. A source Nx_Port that has to send IPv4 packets
to a destination Nx_Port, known by its IPv4 address, MUST perform the
following steps:
1) The source Nx_Port first consults its local mapping tables for a
mapping <destination IPv4 address, N_Port_Name, N_Port_ID>.
2) If such a mapping is found, and a valid Port Login is in place
with the destination Nx_Port, then the source Nx_Port sends the
IPv4 packets to the destination Nx_Port using the retrieved
N_Port_ID as D_ID.
3) If such a mapping is not found, or a valid Port Login is not in
place with the destination Nx_Port, then the source Nx_Port sends
a broadcast FC ARP Request (see section 10) to its connected FC
network.
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RFC 4338 IP over Fibre Channel January 2006
4) When a broadcast FC ARP Request is received by the Nx_Port with
the matching IPv4 address, that Nx_Port caches the information
carried in the FC ARP Request in its local mapping tables and
generates a unicast FC ARP Reply. If a valid Port Login to the
Nx_Port that sent the broadcast FC ARP Request does not exist, the
Nx_Port MUST perform such a Port Login, and then use it for the
unicast reply. The N_Port_ID to which the Port Login is directed
is taken from the N_Port_ID field of the Sender HW Address field
in the received FC ARP packet.
5) If no Nx_Port has the matching IPv4 address, no unicast FC ARP
Reply is returned.
10. Address Mapping for Multicast
IPv6 multicast packets, IPv4 multicast/broadcast packets, and ARP
broadcast packets MUST be mapped to FC Sequences addressed to the
broadcast N_Port_ID 0xFFFFFF, sent in FC Class 3 in a unidirectional
Exchange (see section 12). Appendix A specifies how to transmit a
Class 3 broadcast FC Sequence over various Fibre Channel topologies.
The Destination N_Port_Name field of the FC Network_Header MUST be
set to the value:
- for broadcast ARP and IPv4 packets: 0x10-00-FF-FF-FF-FF-FF-FF;
- for multicast IPv6 packets: 0x10-00-33-33-XX-YY-ZZ-QQ, where
XX-YY-ZZ-QQ are the 4 least significant octets of the multicast
destination IPv6 address;
- for multicast IPv4 packets: 0x10-00-01-00-5E-XX-YY-ZZ, where the
23 least significant bits of XX-YY-ZZ are the 23 least significant
bits of the multicast destination IPv4 address and the most
significant bit of XX-YY-ZZ is set to zero.
An Nx_Port supporting IPv6 or IPv4 MUST be able to map a received
broadcast Class 3 Device_Data FC frame to an implicit Port Login
context in order to handle IPv6 multicast packets, IPv4 multicast or
broadcast packets, and ARP broadcast packets. The receive data field
size of this implicit Port Login MUST be the same across all the
Nx_Ports connected to the same Fabric, otherwise FC broadcast
transmission does not work. In order to reduce the need for FC
Sequence segmentation, the receive data field size of this implicit
Port Login SHOULD be 1024 octets. This receive data field size
requirement applies to broadcast Device_Data FC frames, not to ELSes.
Receiving an FC Sequence carrying an IPv6 multicast packet, an IPv4
multicast/broadcast packet, or an FC ARP broadcast packet triggers
some additional processing by the Nx_Port when that IPv6, IPv4, or
FC ARP packet requires a unicast reply. In this case, if a valid
Port Login to the Nx_Port that sent the multicast or broadcast packet
DeSanti, et al. Standards Track PAGE 22
RFC 4338 IP over Fibre Channel January 2006
does not exist, the Nx_Port MUST perform such a Port Login, and then
use it for the unicast reply. In the case of Neighbor Discovery
messages [DISC], the N_Port_ID to which the Port Login is directed is
taken from the N_Port_ID field of the Source Link-layer Address in
the received Neighbor Discovery message. In the case of FC ARP
messages, the N_Port_ID to which the Port Login is directed is taken
from the N_Port_ID field of the Sender HW Address field in the
received FC ARP packet.
As an example, if a received broadcast FC Sequence carries an IPv6
multicast unsolicited Router Advertisement [DISC], the receiving
Nx_Port processes it simply by passing the carried IPv6 packet to the
IPv6 layer. Instead, if a received broadcast FC Sequence carries an
IPv6 multicast solicitation message [DISC] requiring a unicast reply,
and no valid Port Login exists with the Nx_Port sender of the
multicast packet, then a Port Login MUST be performed in order to
send the unicast reply message. If a received broadcast FC Sequence
carries an IPv6 multicast solicitation message [DISC] requiring a
multicast reply, the reply is sent to the broadcast N_Port_ID
0xFFFFFF.
11. Sequence Management
FC Sequences carrying IPv6, IPv4, or ARP packets are REQUIRED to be
non-streamed [FC-FS]. In order to avoid missing FC frame aliasing by
Sequence_ID reuse, an Nx_Port supporting IPv6 or IPv4 is REQUIRED to
use continuously increasing SEQ_CNT [FC-FS]. Each Exchange MUST
start by setting SEQ_CNT to zero in the first frame; every frame
transmitted after that MUST increment the previous SEQ_CNT by one.
The Continue Sequence Condition field in the F_CTL field of the FC
Header MUST be set to zero [FC-FS].
12. Exchange Management
To transmit IPv6, IPv4, or ARP packets to another Nx_Port or to a
multicast/broadcast address, an Nx_Port MUST use dedicated
unidirectional Exchanges (i.e., Exchanges dedicated to IPv6, IPv4, or
ARP packet transmission and that do not transfer Sequence
Initiative). As such, the Sequence Initiative bit in the F_CTL field
of the FC Header MUST be set to zero [FC-FS]. The RX_ID field of the
FC Header MUST be set to 0xFFFF.
Unicast FC Sequences carrying unicast Control Protocol packets (e.g.,
ARP packets; IPv6 packets carrying ICMPv6 [ICMPv6], Neighbor
Discovery [DISC], or Multicast Listener Discovery [MLDv2] messages;
IPv4 packets carrying ICMP [ICMPv4] or IGMP [IGMPv3] messages) SHOULD
be sent in short-lived unidirectional Exchanges (i.e., Exchanges
containing only one Sequence, in which both the First_Sequence and
DeSanti, et al. Standards Track PAGE 23
RFC 4338 IP over Fibre Channel January 2006
Last_Sequence bits in the F_CTL field of the FC Header are set to one
[FC-FS]). Unicast FC Sequences carrying other IPv6 and IPv4 packets
(i.e., unicast IP packets carrying data traffic) MUST be sent in a
long-lived unidirectional Exchange (i.e., an Exchange containing one
or more Sequences). IP multicast packets MUST NOT be carried in
unicast FC Sequences (see section 10).
Broadcast FC Sequences carrying multicast or broadcast Control
Protocol packets (e.g., ARP packets; IPv6 packets carrying ICMPv6
[ICMPv6], Neighbor Discovery [DISC], or Multicast Listener Discovery
[MLDv2] messages; IPv4 packets carrying ICMP [ICMPv4] or IGMP
[IGMPv3] messages) MUST be sent in short-lived unidirectional
Exchanges. Broadcast FC Sequences carrying other IPv6 or IPv4
multicast traffic (i.e., multicast IP packets carrying data traffic)
MAY be sent in long-lived unidirectional Exchanges to enable a more
efficient multicast distribution.
Reasons to terminate a long-lived Exchange include the termination of
Port Login and the completion of the IP communication. A long-lived
Exchange MAY be terminated by setting the Last_Sequence bit in the
F_CTL field of the FC Header to one, or via the ABTS (Abort Sequence)
protocol [FC-FS]. A long-lived Exchange SHOULD NOT be terminated by
transmitting the LOGO ELS, since this may terminate active Exchanges
on other FC-4s [FC-FS].
13. Interoperability with RFC 2625
The IPv4 encapsulation defined in this document, along with Exchange
and Sequence management, are as defined in [RFC 2625].
Implementations following this specification are expected to
interoperate with implementations compliant to [RFC 2625] for IPv4
packet transmission and reception.
The main difference between this document and [RFC 2625] is in the
address resolution procedure. [RFC 2625] uses the Ethernet format of
the ARP protocol and requires all Nx_Ports to have a format 0x1
N_Port_Name. This specification defines a Fibre Channel format for
the ARP protocol that supports all commonly used N_Port_Names. In
addition, this specification does not use FARP [RFC 2625].
An Nx_Port following this specification, and not having a format 0x1
N_Port_Name, is able to interoperate with an [RFC 2625]
implementation by manually configuring the mapping <destination IPv4
address, N_Port_Name, N_Port_ID> on the involved Nx_Ports. Through
this manual configuration, the ARP protocol does not need to be
performed. However, IPv4 communication is not possible if the
[RFC 2625] implementation strictly enforces the requirement for
Nx_Ports to use N_Port_Names of format 0x1.
DeSanti, et al. Standards Track PAGE 24
RFC 4338 IP over Fibre Channel January 2006
An Nx_Port following this specification, and having a format 0x1
N_Port_Name, is able to interoperate with an [RFC 2625]
implementation by manually configuring the mapping <destination IPv4
address, N_Port_Name, N_Port_ID> on the involved Nx_Ports, or by
performing the IPv4 address resolution in compatibility mode, as
described below:
- When IPv4 address resolution is attempted, the Nx_Port MUST send
two ARP Requests, the first one according to the FC ARP format and
the second one according to the Ethernet ARP format. If only an
Ethernet ARP Reply is received, it provides the N_Port_Name of the
Nx_Port having the destination IPv4 address. The N_Port_ID
associated with the N_Port_Name received in an Ethernet ARP Reply
may be retrieved from the S_ID field of the received ARP Reply, or
by querying the Fibre Channel Name Server;
- The Nx_Port MUST respond to a received Ethernet ARP Request with
an Ethernet ARP Reply;
- The Nx_Port MAY respond to FARP Requests [RFC 2625].
The reception of a particular format of ARP message does not imply
that the sending Nx_Port will continue to use the same format later.
Support of compatibility mode is REQUIRED by each implementation.
The use of compatibility mode MUST be administratively configurable.
14. Security Considerations
IPv6, IPv4, and ARP do not introduce any additional security concerns
beyond those that already exist within the Fibre Channel protocols.
Zoning techniques based on FC Name Server masking (soft zoning) do
not work with IPv6 and IPv4, because IPv6 and IPv4 over Fibre Channel
do not use the FC Name Server. The FC ESP_Header [FC-FS] may be used
to secure the FC frames composing FC Sequences carrying IPv6, IPv4,
and ARP packets. All the techniques defined to secure IP traffic at
the IP layer may be used in a Fibre Channel environment.
15. IANA Considerations
The directory of ARP parameters has been updated to reference this
document for hardware type 18.
16. Acknowledgements
The authors would like to acknowledge the ANSI INCITS T11.3 Task
Group members who reviewed this document as well as the authors of
[RFC 2625] and [RFC 3831]. The authors also thank the IMSS WG and
Brian Haberman for their review and comments.
DeSanti, et al. Standards Track PAGE 25
RFC 4338 IP over Fibre Channel January 2006
17. Normative References
[FC-FS] ANSI INCITS 373-2003, "Fibre Channel - Framing and
Signaling (FC-FS)".
[FC-AL-2] ANSI INCITS 332-1999, "Fibre Channel - Arbitrated Loop-2
(FC-AL-2)".
[IPv6] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[AARCH] Hinden, R. and S. Deering, "Internet Protocol Version 6
(IPv6) Addressing Architecture", RFC 3513, April 2003.
[ACONF] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.
[DISC] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC 2461, December
1998.
[PMTUD6] McCann, J., Deering, S., and J. Mogul, "Path MTU
Discovery for IP version 6", RFC 1981, August 1996.
[IPv4] Postel, J., "Internet Protocol", STD 5, RFC 791,
September 1981.
[ARP] Plummer, D., "Ethernet Address Resolution Protocol: Or
converting network protocol addresses to 48.bit Ethernet
address for transmission on Ethernet hardware", STD 37,
RFC 826, November 1982.
[IEEE-LLC] IEEE Std 802-2001, "IEEE Standard for Local and
Metropolitan Area Networks: Overview and Architecture".
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
18. Informative References
[RFC 3831] DeSanti, C., "Transmission of IPv6 Packets over Fibre
Channel", RFC 3831, July 2004.
[RFC 2625] Rajagopal, M., Bhagwat, R., and W. Rickard, "IP and ARP
over Fibre Channel", RFC 2625, June 1999.
[MLDv2] Vida, R. and L. Costa, "Multicast Listener Discovery
Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.
DeSanti, et al. Standards Track PAGE 26
RFC 4338 IP over Fibre Channel January 2006
[IGMPv3] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
Thyagarajan, "Internet Group Management Protocol, Version
3", RFC 3376, October 2002.
[PMTUD4] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
November 1990.
[ICMPv6] Conta, A. and S. Deering, "Internet Control Message
Protocol (ICMPv6) for the Internet Protocol Version 6
(IPv6) Specification", RFC 2463, December 1998.
[ICMPv4] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, September 1981.
[EUI64] "Guidelines For 64-bit Global Identifier (EUI-64)
Registration Authority",
http://standards.ieee.org/regauth/oui/tutorials/
EUI64.html
DeSanti, et al. Standards Track PAGE 27
RFC 4338 IP over Fibre Channel January 2006
A. Transmission of a Broadcast FC Sequence over FC Topologies
(Informative)
A.1. Point-to-Point Topology
No particular mechanisms are required for this case. The Nx_Port
connected at the other side of the cable receives the broadcast FC
Sequence having D_ID 0xFFFFFF.
A.2. Private Loop Topology
An NL_Port attached to a private loop must transmit a Class 3
broadcast FC Sequence by using the OPN(fr) primitive signal
[FC-AL-2].
1) The source NL_Port first sends an Open Broadcast Replicate
(OPN(fr)) primitive signal, forcing all the NL_Ports in the loop
(except itself) to replicate the frames that they receive while
examining the FC Header's D_ID field.
2) The source NL_Port then removes the OPN(fr) signal when it returns
to it.
3) The source NL_Port then sends the Class 3 broadcast FC Sequence
having D_ID 0xFFFFFF.
A.3. Public Loop Topology
An NL_Port attached to a public loop must not use the OPN(fr)
primitive signal. Rather, it must send the Class 3 broadcast FC
Sequence having D_ID 0xFFFFFF to the FL_Port at AL_PA = 0x00
[FC-AL-2].
The Fabric propagates the broadcast to all other FC_Ports [FC-FS],
including the FL_Port that the broadcast arrives on. This includes
all F_Ports, and other FL_Ports.
Each FL_Port propagates the broadcast by using the primitive signal
OPN(fr), in order to prepare the loop to receive the broadcast
sequence.
A.4. Fabric Topology
An N_Port connected to an F_Port must transmit the Class 3 broadcast
FC Sequence having D_ID 0xFFFFFF to the F_Port. The Fabric
propagates the broadcast to all other FC_Ports [FC-FS].
DeSanti, et al. Standards Track PAGE 28
RFC 4338 IP over Fibre Channel January 2006
B. Validation of the <N_Port_Name, N_Port_ID> Mapping
(Informative)
B.1. Overview
At all times, the <N_Port_Name, N_Port_ID> mapping must be valid
before use.
After an FC link interruption occurs, the N_Port_ID of an Nx_Port may
change, as well as the N_Port_IDs of all other Nx_Ports that have
previously performed Port Login with this Nx_Port. Because of this,
address validation is required after a Loop Initialization Primitive
Sequence (LIP) in a loop topology [FC-AL-2] or after Not_Operational
Primitive Sequence / Offline Primitive Sequence (NOS/OLS) in a
point-to-point topology [FC-FS].
N_Port_IDs do not change as a result of Link Reset (LR) [FC-FS];
thus, address validation is not required in this case.
B.2. FC Layer Address Validation in a Point-to-Point Topology
No validation is required after Link Reset (LR). In a point-to-point
topology, NOS/OLS causes implicit Logout of each N_Port and after an
NOS/OLS each N_Port must again perform a Port Login [FC-FS].
B.3. FC Layer Address Validation in a Private Loop Topology
After a LIP [FC-AL-2], an NL_Port must not transmit any data to
another NL_Port until the address of the other port has been
validated. The validation consists of completing the Address
Discovery procedure with the ADISC ELS [FC-FS].
If the three FC addresses (N_Port_ID, N_Port_Name, Node_Name) of a
logged remote NL_Port exactly match the values prior to the LIP, then
any active Exchange with that NL_Port may continue.
If any of the three FC addresses has changed, then the remote NL_Port
must be logged out.
If an NL_Port's N_Port_ID changes after a LIP, then all active
logged-in NL_Ports must be logged out.
DeSanti, et al. Standards Track PAGE 29
RFC 4338 IP over Fibre Channel January 2006
B.4. FC Layer Address Validation in a Public Loop Topology
A Fabric Address Notification (FAN) ELS may be sent by the Fabric to
all known previously logged-in NL_Ports following an initialization
event. Therefore, after a LIP [FC-AL-2], NL_Ports may wait for this
notification to arrive, or they may perform an FLOGI.
If the F_Port_Name and Fabric_Name contained in the FAN ELS or FLOGI
response exactly match the values before the LIP and if the AL_PA
[FC-AL-2] obtained by the NL_Port is the same as the one before the
LIP, then the port may resume all Exchanges. If not, then FLOGI must
be performed with the Fabric and all logged-in Nx_Ports must be
logged out.
A public loop NL_Port must perform the private loop validation as
specified in section B.3 to any NL_Port on the local loop that has an
N_Port_ID of the form 0x00-00-XX (i.e., to any private loop NL_Port).
B.5. FC Layer Address Validation in a Fabric Topology
No validation is required after Link Reset (LR).
After NOS/OLS, an N_Port must perform FLOGI. If, after FLOGI, the
N_Port's N_Port_ID, the F_Port_Name, and the Fabric_Name are the same
as before the NOS/OLS, then the N_Port may resume all Exchanges. If
not, all logged-in Nx_Ports must be logged out [FC-FS].
C. Fibre Channel Bit and Byte Numbering Guidance
Both Fibre Channel and IETF standards use the same byte transmission
order. However, the bit numbering is different.
Fibre Channel bit numbering can be observed if the data structure
heading shown in figure 24 is cut and pasted at the top of the
figures present in this document.
3 2 1 0
1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 24: Fibre Channel Bit Numbering
DeSanti, et al. Standards Track PAGE 30
RFC 4338 IP over Fibre Channel January 2006
D. Changes from RFC 2625
- Nx_Ports with N_Port_Name format 0x2, 0x5, 0xC, 0xD, 0xE, and 0xF
are supported, in addition to format 0x1;
- An IP-capable Nx_Port MUST support Class 3;
- An IP-capable Nx_Port MUST support continuously increasing
SEQ_CNT;
- An IP-capable Nx_Port SHOULD support a receive data field size for
Device_Data FC frames of at least 1024 octets;
- The FC ESP_Header MAY be used;
- FC Classes of services other than 3 are not recommended;
- Defined a new FC ARP format;
- Removed support for FARP because some FC implementations do not
tolerate receiving broadcast ELSes;
- Added support for IPv4 multicast;
- Clarified the usage of the CS_CTL and Parameter fields of the FC
Header;
- Clarified the usage of FC Classes of service;
- Clarified the usage of FC Sequences and Exchanges.
E. Changes from RFC 3831
- Clarified the usage of the CS_CTL and Parameter fields of the FC
Header;
- Clarified the usage of FC Classes of service;
- Clarified and updated the mapping of IPv6 multicast on Fibre
Channel;
- Clarified the usage of FC Sequences and Exchanges;
- Clarified and updated the format of the Neighbor Discovery
Link-layer option for Fibre Channel.
DeSanti, et al. Standards Track PAGE 31
RFC 4338 IP over Fibre Channel January 2006
Authors' Addresses
Claudio DeSanti
Cisco Systems, Inc.
170 W. Tasman Dr.
San Jose, CA 95134
USA
Phone: +1 408 853-9172
EMail: cds@cisco.com
Craig W. Carlson
QLogic Corporation
6321 Bury Drive
Eden Prairie, MN 55346
USA
Phone: +1 952 932-4064
EMail: craig.carlson@qlogic.com
Robert Nixon
Emulex
3333 Susan Street
Costa Mesa, CA 92626
USA
Phone: +1 714 885-3525
EMail: bob.nixon@emulex.com
DeSanti, et al. Standards Track PAGE 32
RFC 4338 IP over Fibre Channel January 2006
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DeSanti, et al. Standards Track PAGE 33
Transmission of IPv6, IPv4, and Address Resolution Protocol (ARP) Packets over Fibre Channel
RFC TOTAL SIZE: 75541 bytes
PUBLICATION DATE: Monday, January 23rd, 2006
LEGAL RIGHTS: The IETF Trust (see BCP 78)
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