Fibre Channel (FC) is a high speed serial interface technology that
supports several Upper Layer Protocols including Small Computer
System Interface (SCSI) and IPv4 as specified in [IPFC].
The purpose of this document is to specify a way of encapsulating IP
version 6 [IPv6] over Fibre Channel and to describe a method of
forming IPv6 link-local addresses [AARCH] and statelessly
autoconfigured addresses on Fibre Channel networks. This document
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.
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].
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RFC 3831 IPv6 over Fibre Channel July 2004
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 is more precisely called an N_Port. A Node Port that is
capable of operating in a loop topology using the loop specific
protocols is designated as an NL_Port. The term Nx_Port is used to
generically indicate these two kinds of Node Port.
A Fabric Port is more precisely called an F_Port. A Fabric Port that
is capable of operating in a loop topology using the loop specific
protocols is designated as an FL_Port. The term Fx_Port is used to
generically indicate these two kinds of Fabric Port.
From an IPv6 point of view, a Fibre Channel network, built with any
combination of the FC topologies described above, is an IPv6 Link
[IPv6]. IPv6-capable Nx_Ports are what [IPv6] calls Interfaces.
Fibre Channel entities are identified by permanent 64 bit long
Name_Identifiers. [FC-FS] defines several formats of
Name_Identifiers. The value of the first four bits defines the
format of a Name_Identifier. These names are referred to in a more
precise 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.
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RFC 3831 IPv6 over Fibre Channel July 2004
An Nx_Port connected to a Fibre Channel network is associated with
two identifiers, its permanent N_Port_Name and a volatile 24 bit
address called N_Port_ID. The N_Port_Name is used to identify the
Nx_Port, while 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
ELS), or implicit, in which the parameters are specified by
configuration or other methods.
[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 control functions necessary for information
transfer. The FC-4 level supports Upper Level Protocols, such as
IPv4, IPv6 or SCSI. The Fibre Channel frame format is depicted in
figure 1.
+-----+-----------+-----------+--------//-------+-----+-----+
| | | Data Field | | |
| SOF | FC Header |<--------------------------->| CRC | EOF |
| | | Optional | Frame | | |
| | | Header(s) | Payload | | |
+-----+-----------+-----------+--------//-------+-----+-----+
Fig. 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 CRC is 4 octets
long and uses the same 32-bit polynomial used in FDDI.
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RFC 3831 IPv6 over Fibre Channel July 2004
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:
- 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.
An application level payload such as IPv6 is called Information Unit
at the FC-4 level of Fibre Channel. Each FC-4 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 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 related 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
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RFC 3831 IPv6 over Fibre Channel July 2004
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.
This specification requires an IPv6 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 6.1). IPv6 support for other
Name_Identifier formats is outside the scope of this
specification;
- 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;
- It SHOULD support a receive data field size for Device_Data FC
frames of at least 1024 octets.
An IPv6 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 IPv6 packet MUST carry
the FC Network_Header [FC-FS] and the LLC/SNAP header [IEEE-LLC],
resulting in the FC Information Unit format depicted in figure 2.
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RFC 3831 IPv6 over Fibre Channel July 2004
+---------------+---------------+---------------+---------------+
| |
+- -+
| Network_Header |
+- (16 octets) -+
| |
+- -+
| |
+---------------+---------------+---------------+---------------+
| LLC/SNAP header |
+- (8 octets) -+
| |
+---------------+---------------+---------------+---------------+
| |
+- -+
/ IPv6 Packet /
/ /
+- -+
| |
+---------------+---------------+---------------+---------------+
Fig. 2: FC Information Unit Mapping an IPv6 Packet
The FC ESP_Header [FC-FS] MAY be used to secure the FC frames
composing the FC Sequence. [AH] or [ESP] may be used to provide
security at the IPv6 layer. Other types of FC Optional Header MUST
NOT be used in an IPv6 FC Sequence.
Typically, a Sequence consists of more than one frame. Only 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
depicted in figure 3.
First Frame of an IPv6 FC Sequence
+-----------+-------------------+-----------------+-------//--------+
| FC Header | FC Network_Header | LLC/SNAP header | First chunk of |
| | | | the IPv6 Packet |
+-----------+-------------------+-----------------+-------//--------+
Subsequent Frames of an IPv6 FC Sequence
+-----------+-----------------//------------------+
| FC Header | Additional chunk of the IPv6 Packet |
+-----------+----------------//-------------------+
Fig. 3: Optional Headers in an IPv6 FC Sequence
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RFC 3831 IPv6 over Fibre Channel July 2004
This specification uses FC Class 3. IPv6 packets carrying Neighbor
Discovery [DISC] messages MUST be encapsulated in Class 3 FC frames.
Other IPv6 packets SHOULD use Class 3 as well. The use of other
Classes of service is outside the scope of this specification.
The fields of the Fibre Channel Header are depicted in figure 4. The
D_ID and S_ID fields contain respectively the destination N_Port_ID
and the source N_Port_ID. To encapsulate IPv6 over Fibre Channel the
following code points 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: 0x0
- DF_CTL: 0x20 (Network_Header) for the first FC frame of an IPv6
Sequence, 0x00 for the following FC frames. If the FC ESP_Header
is used, then 0x60 for the first FC frame of an IPv6 Sequence,
0x40 for the following FC frames.
- F_CTL, SEQ_ID, SEQ_CNT, OX_ID, RX_ID, Parameter: see section 10,
section 11, and [FC-FS] for additional requirements.
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 |
+---------------+---------------+---------------+---------------+
Fig. 4: FC Header Format
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RFC 3831 IPv6 over Fibre Channel July 2004
The fields of the FC Network_Header are depicted in figure 5. For
use with IPv6 the N_Port_Names formats MUST be one of 0x1, 0x2, 0x5,
0xC, 0xD, 0xE, 0xF. IPv6 support for other Name_Identifier formats
is outside the scope of this specification.
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 -+
| |
+---------------------------------------------------------------+
Fig. 5: FC Network_Header Format
IPv6 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.
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RFC 3831 IPv6 over Fibre Channel July 2004
The default MTU size for IPv6 [IPv6] packets over Fibre Channel is
65280 octets. 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 [PMTUD], or at least maintain different MTU values for
on-link and off-link destinations.
For correct operation in a routed environment, it is critically
important to configure an appropriate MTU option in Router
Advertisements.
For correct operation 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 which is
connected to a medium with a default MTU larger than the smallest
MTU.
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
bit of the OUI field of the derived EUI-64 address.
[FC-FS] specifies a method to map format 0x1 (IEEE 48 bit address),
or 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.
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RFC 3831 IPv6 over Fibre Channel July 2004
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.
The Name_Identifier format 0x2 is depicted 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 1 0| Vendor Specific | OUI |
+-------+-------+---------------+---------------+---------------+
| OUI | VSID |
+---------------+---------------+---------------+---------------+
Fig. 10: Format 0x2 Name_Identifier
The EUI-64 address derived from this Name_Identifier has the format
depicted in figure 11 [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 |
+---------------+-----------------------+-------+---------------+
Fig. 11: 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. So 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
depicted in figure 12.
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 |
+---------------+-----------------------+-------+---------------+
Fig. 12: 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.
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RFC 3831 IPv6 over Fibre Channel July 2004
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 from the
OUI the Universal/Local and Individual/Group bits, 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 1| OUI[0..5] | OUI[8..23] | VSID |
+---+-----------+---------------+---------------+---------------+
| VSID |
+---------------+---------------+---------------+---------------+
Fig. 16: EUI-64 Mapped Name_Identifiers Format
The EUI-64 address used to generate the Name_Identifier shown in
figure 16 has the format depicted 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OUI[0..5] |0 0| OUI[8..23] | VSID |
+-----------+---+---------------+---------------+---------------+
| VSID |
+---------------+---------------+---------------+---------------+
Fig. 17: 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 depicted
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] |1 0| OUI[8..23] | VSID |
+-----------+---+---------------+---------------+---------------+
| VSID |
+---------------+---------------+---------------+---------------+
Fig. 18: IPv6 Interface ID from an EUI-64 Mapped Name_Identifier
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RFC 3831 IPv6 over Fibre Channel July 2004
As an example, the FC Name_Identifier 0xCD-63-46-AB-01-25-78-9A
generates the IPv6 Interface Identifier 3663:46AB:0125:789A.
The IPv6 link-local address [AARCH] for an Nx_Port is formed by
appending the Interface Identifier, as defined in section 6, to the
prefix FE80::/64. The resulting address is depicted in figure 19.
10 bits 54 bits 64 bits
+----------+-----------------------+----------------------------+
|1111111010| (zeros) | Interface Identifier |
+----------+-----------------------+----------------------------+
Fig. 19: IPv6 link-local Address Format
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, while the
N_Port_ID is used to route frames to the Nx_Port. Both FC addresses
are required to resolve an IPv6 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).
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 depicted
in figure 20 when the link layer is Fibre Channel.
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 | Reserved |
+---------------+---------------+---------------+---------------+
| |
+- N_Port_Name -+
| |
+---------------+---------------+---------------+---------------+
| Reserved | N_Port_ID |
+---------------+---------------+---------------+---------------+
Fig. 20: Source/Target Link-layer Address option for Fibre Channel
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RFC 3831 IPv6 over Fibre Channel July 2004
Type: 1 for Source Link-layer address.
2 for Target Link-layer address.
Length: 2 (in units of 8 octets).
N_Port_Name: This field contains the Nx_Port's N_Port_Name.
N_Port_ID: This field contains the Nx_Port's N_Port_ID.
Reserved fields MUST be zero when transmitting, and MUST be ignored
when receiving.
By default, all best-effort IPv6 multicast packets MUST be mapped to
FC Sequences addressed to the broadcast N_Port_ID 0xFF-FF-FF. In
particular, datagrams addressed to all-nodes multicast address,
all-routers multicast address, and solicited-node multicast addresses
[AARCH] MUST be sent as Class 3 FC Sequences addressed to the
broadcast N_Port_ID 0xFF-FF-FF. In this case, the Destination
N_Port_Name field of the FC Network_Header MUST be set to the value
0x10-00-FF-FF-FF-FF-FF-FF. Appendix A specifies how to transmit a
Class 3 broadcast FC Sequence over various Fibre Channel topologies.
An Nx_Port supporting IPv6 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. 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 ELSs.
Receiving an FC Sequence carrying an IPv6 multicast packet MAY
trigger some additional processing by the Nx_Port if that IPv6 packet
requires a unicast reply. In this case, if a valid Port Login to the
Nx_Port that sent the IPv6 multicast packet does not exist, the
Nx_Port MUST perform such a Port Login, and then use it for the
unicast IPv6 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/Target Link-layer Address
option.
As an example, an Nx_Port processes a received broadcast FC Sequence
carrying an IPv6 multicast unsolicited router advertisement [DISC]
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
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RFC 3831 IPv6 over Fibre Channel July 2004
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 0xFF-FF-FF.
Best-effort IPv6 multicast for other multicast group addresses MAY
use Fibre Channel Multicast Groups [FC-FS], if supported by the
particular FC topology and implementation.
FC Sequences are REQUIRED to be non-streamed. In order to avoid
missing FC frame aliasing by Sequence_ID reuse, an Nx_Port supporting
IPv6 is REQUIRED to use continuously increasing SEQ_CNT [FC-FS].
Each Exchange MUST start with SEQ_CNT = 0 in the first frame, and
every frame transmitted after that MUST increment the previous
SEQ_CNT by one. Any frames received from the other N_Port in the
Exchange shall have no effect on the transmitted SEQ_CNT.
To transfer IPv6 packets, each Nx_Port MUST have a dedicated Exchange
for sending data to each Nx_Port in the network and a dedicated
Exchange for receiving data from each Nx_Port.
An Exchange Responder is not required to assign RX_IDs. If an RX_ID
of 0xFFFF is assigned, the Exchange Responder is identifying
Exchanges based on S_ID / D_ID / OX_ID only.
When an Exchange is created between two Nx_Ports for unicast IPv6
packets, it remains active while the Nx_Ports are logged in with each
other. Each FC broadcast and ELS [FC-FS] SHOULD use a separate short
lived Exchange.
For IPv6, Exchanges MUST NOT transfer Sequence Initiative, because
they are used in a unidirectional mode. The Sequence Initiative bit
in the F_CTL field of the FC Header [FC-FS] MUST be set to 0.
The mechanism for aging or expiring exchanges based on activity,
timeout, or other methods is outside the scope of this document.
The Exchange Originator MAY terminate Exchanges by setting the F_CTL
LS bit [FC-FS]. Exchanges MAY be torn down by the Exchange
Originator or Exchange Responder by using the ABTS (Abort Sequence)
protocol [FC-FS]. IPv6 Exchanges SHOULD NOT be terminated by Logout,
since this may terminate active Exchanges on other FC-4s [FC-FS].
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RFC 3831 IPv6 over Fibre Channel July 2004
IPv6 does 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, because IPv6 over Fibre Channel does 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 packets. All the
techniques defined to secure IPv6 traffic at the IPv6 layer may be
used in a Fibre Channel environment.
The author would like to acknowledge the authors of [IPFC], [ETHER],
and [IPv6-1394], since some part of this document has been derived
from them, as well as the ANSI INCITS T11.3 Task Group members who
reviewed this document.
[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.
[PMTUD] McCann, J., Deering, S., and J. Mogul, "Path MTU
Discovery for IP version 6", RFC 1981, August 1996.
[IEEE-LLC] IEEE Std 802-2001, "IEEE Standard for Local and
Metropolitan Area Networks: Overview and Architecture".
DeSanti Standards Track [Page 18]
RFC 3831 IPv6 over Fibre Channel July 2004
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[IPFC] Rajagopal, M., Bhagwat, R., and W. Rickard, "IP and ARP
over Fibre Channel", RFC 2625, June 1999.
[AH] Kent, S. and R. Atkinson, "IP Authentication Header", RFC
2402, November 1998.
[ESP] Kent, S. and R. Atkinson, "IP Encapsulating Security
Payload (ESP)", RFC 2406, November 1998.
[EUI64] "Guidelines For 64-bit Global Identifier (EUI-64)",
http://standards.ieee.org/db/oui/tutorials/EUI64.html
[ETHER] Crawford, M., "Transmission of IPv6 Packets over Ethernet
Networks", RFC 2464, December 1998.
[IPv6-1394] Fujisawa, K. and A. Onoe, "Transmission of IPv6 Packets
over IEEE 1394 Networks", RFC 3146, October 2001.
DeSanti Standards Track [Page 19]
RFC 3831 IPv6 over Fibre Channel July 2004
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.
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].
a) 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.
b) The source NL_Port then removes the OPN(fr) signal when it returns
to it.
c) The source NL_Port then sends the Class 3 broadcast FC Sequence
having D_ID 0xFFFFFF.
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 which 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.
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].
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RFC 3831 IPv6 over Fibre Channel July 2004
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 LIP in a loop topology
[FC-AL-2] or after 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.
No validation is required after LR. In a point-to-point topology,
NOS/OLS causes implicit Logout of each N_Port and after a NOS/OLS
each N_Port must again perform a Port Login [FC-FS].
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 either ADISC or
PDISC [FC-FS].
For a requester, this specification prohibits PDISC and requires
ADISC. As a responder, an implementation may need to respond to both
ADISC and PDISC for compatibility with other FC specifications.
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.
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RFC 3831 IPv6 over Fibre Channel July 2004
A 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.
No validation is required after LR (link reset).
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].
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 21 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fig. 21: Fibre Channel Bit Numbering
DeSanti Standards Track [Page 22]
RFC 3831 IPv6 over Fibre Channel July 2004
Author's Address
Claudio DeSanti
Cisco Systems, Inc.
170 W. Tasman Dr.
San Jose, CA 95134
USA
Phone: +1 408 853-9172
EMail: cds@cisco.com
DeSanti Standards Track [Page 23]
RFC 3831 IPv6 over Fibre Channel July 2004
Full Copyright Statement
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DeSanti Standards Track [Page 24]