IPv4 and ARP over Fibre Channel draft-desanti-imss-ipv4-over-fibre-channel-00.txt
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Transcript of IPv4 and ARP over Fibre Channel draft-desanti-imss-ipv4-over-fibre-channel-00.txt
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IPv4 and ARP over Fibre Channeldraft-desanti-imss-ipv4-over-fibre-channel-00.txt
61th IETF, Washington DC
Claudio DeSanti
222Claudio DeSanti
History
• RFC 2625 has been evaluated for advancement to Draft Standard status
• Discovered that some implementations are not following RFC 2625 because of:
N_Port_Name format restriction
RFC 2625 allowed only NAA 1
Use of FARP
RFC 2625 required its support for interoperability
Major problems
• The new specification tries to resolve these issues
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RFC 2625 ARP Format
Sender
Target IP Address
HW Type = Ethernet
HW Len = 6
ProtocolType = IPv4
Proto Len = 4 Opcode
Sender HW Address
IP Address
Target HW Address
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RFC 2625 IPv4 Address Resolution (1)
ARP Request:- Sender HW Address = HW(A)- Sender IP Address = IP(A)- Target HW Address = ??- Target IP Address IP(B)
A
B C D
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RFC 2625 IPv4 Address Resolution (2)
ARP Reply:- Sender HW Address = HW(B)- Sender IP Address = IP(B)- Target HW Address = HW(A)- Target IP Address IP(A)
A
B C D
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RFC 2625 IPv4 Address Resolution (3)
FARP Request:- Requester N_Port_Name- Requester N_Port_ID- Responder N_Port_Name- Responder N_Port_ID = ??
A
B C D
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RFC 2625 IPv4 Address Resolution (4)
FARP Reply:- Requester N_Port_Name- Requester N_Port_ID- Responder N_Port_Name- Responder N_Port_ID
A
B C D
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The Nasty FARP…
• FARP is a broadcast ELS
• Several (old?) disk implementation do (did?) not tolerate receiving unexpected ELSs
They may reinitialize or issue some SCSI errors
B resolving C’s IPv4 address may cause I/O errors to A!
• Some vendors did not implement FARP at all!
• The Switch vendors defined “broadcast zoning” in FC-SW-3 to administratively limit the scope of the FARP broadcast ELS
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New ARP Format
Sender HW Address
HW Type = Fibre Channel ProtocolType = IPv4
HW Len = 12 Proto Len = 4 Opcode
Sender IP Address
Target HW Address
Target IP Address
Sender N_Port_Name
Sender N_Port_IDReserved
Target N_Port_Name
Target N_Port_IDReserved
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Updated IPv4 Address Resolution (1)
ARP Request:- Sender HW Address = N_Port_Name(A), N_Port_ID(A)- Sender IP Address = IP(A)- Target HW Address = ??- Target IP Address IP(B)
A
B C D
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Updated IPv4 Address Resolution (2)
ARP Reply:- Sender HW Address = N_Port_Name(B), N_Port_ID(B)- Sender IP Address = IP(B)- Target HW Address = N_Port_Name(A), N_Port_ID(A)- Target IP Address IP(A)
A
B C D
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New Draft Benefits
• All commonly used Name_Identifier formats are supported
• Simplified ARP resolution process
No more need for FARP
• Missing functionality added
IPv4 multicast support
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Backward Compatibility (1)
• Communication between an RFC 2625 implementation and an Nx_Port with NAA ≠ 1
If the RFC 2625 implementation strictly enforces theNAA =1 requirement, no way!
IP encapsulation issue
If the RFC 2625 implementation does not strictly enforce the NAA = 1 requirement, only address resolution does not work
Use manual mapping tables
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Backward Compatibility (2)
• Communication between an RFC 2625 implementation and an Nx_Port with NAA = 1
No issues with IP encapsulation
For address resolution send two ARP requests:
one according to the Fibre Channel format
one according to the Ethernet format
Use the first reply received
Reply with an Ethernet ARP reply to any received Ethernet ARP request
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How to move forward
• There is consensus in T11 in replacing RFC 2625
• Create a combined IPv6/IPv4 document to replace both RFC 2625 and RFC 3831
Easier for implementors to work over it
It shows that IPv6 support is straightforward
Allows “standard developers” to think to both worlds
A single Exchange for IPv4 and IPv6, or one per protocol?
The quality of the combined document is better
The new draft is getting a deeper review