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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: iFCP as an IP Storage Work ItemWe are also not in support of picking up iFCP as a IP Storage Work Item. As we indicated in earlier posts (FC-BB-2 exists thread and the FCIP support for N_Port etc.) we would not be in support of multiple ways (i.e., FCIP and iFCP) in which FC and IP networks/devices are made to coexist. In particular, our reasons for not supporting iFCP as a work item are the following. 1. Confusion in market place The overall goal of iFCP appears to be to leverage investment in IP networking technology for networking storage. In this respect, it is closer in the goal of iSCSI. In a storage network based on IP networking technology, we see iSCSI as a better alternative. It would be confusing to present both iSCSI and iFCP as two technologies for using the IP network for storage. Since the IP Storage Working Group and its members have already invested heavily in standardizing iSCSI, we do not see much value in diluting the efforts on multiple technologies towards the same end goal. 2. Support for existing FC networks FCIP and its coordinated effort with FC-BB-2 supports existing FC networks better. The interoperability issues between FC and IP networks are restricted to the border switches. Other infrastructure needs such as FC Name Server, Fabric Controller etc. are leveraged from standards work already done in T11 working groups. The argument that iFCP is useful in a world of FC devices is not very strong, since FCIP is a solution that not only preserves investment in FC end nodes but also in FC switches. 3. iFCP does not support FC loops and FC E_Port The drafts as submitted do not handle FC loops and FC switches. There were some email discussions where authors indicated that these are trivial to add to iFCP. We do not think it would be trivial to add E_Port support and work through the interoperability issues between iFCP gateways and FC switches. Adding FC loop support and E_Port support to an iFCP gateway would make that gateway device closer to an FC switch, so one could simply use FC switches with B_Port support and FCIP as the tunneling protocol. 4. iFCP adds cost to deployment End nodes may be forced to support both FC N_Port and iSCSI. It is easier for end nodes to just support iSCSI when storage network is based on an IP network. There is also an additional cost in testing a pure iSCSI end node with a bridged FC-iFCP end node. 5. FCIP has broader coverage iFCP implies that it is only useful for translating FCP traffic. FCIP is able to tunnel all FC traffic through its border switches. It is also possible to add N_Port connectivity using FCIP, although such an attempt would also compete with the goals of iSCSI. 6. iFCP addds processing overhead to frames In contrast to iSCSI, iFCP requires examination of every frame and substitution of addresses at both iFCP Portals. This has the potential to add unwanted latencies as well as consume processing overhead on gateways. Given this, it would be hard to compete with cut-through routing based products in a pure FC or IP based storage network. We also do not believe the NAT like function should really be the top priority for the working group to address. As an example, the first NAT RFC was RFC 1631 (which was an Informational RFC from the one vendor), well after several other higher priority items were addressed. We do not believe that FC networks (when deployed in the context of back-end storage) are running out of address space to warrant this to be addressed immediately. Venkat Rangan Rhapsody Networks Inc. http://www.rhapsodynetworks.com -----Original Message----- From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of David Peterson Sent: Wednesday, January 03, 2001 9:42 AM To: Ips@Ece. Cmu. Edu Subject: iFCP as an IP Storage Work Item The iFCP proposal for encapsulating Fibre Channel frames should not be a work item for the IP Storage working group. This view is taken by Cisco Systems and Brocade Communications for the following technical reasons. 1. FCIP is aligned with the existing FC-BB-2 work in progress. 2. FCIP will function with any existing/future FC-4 protocol such as FCP/FCP-2, VI, SRP. 3. A native iSCSI device will provide the same functionality as a device connected to an iFCP gateway. 4. Combining iFCP and FCIP does not make any sense since they are implemented using two different routing planes. In addition, FCIP is a tunneling protocol and requires mimimal processing of the Fibre Channel frame. In contrast, iFCP is a gateway protocol and requires much more processing such as the reading and modification of the Fibre Channel header, augmentation data for specific Fibre Channel Extended Link Services, and special handling of specific Fibre Channel Extended Link Services. 5. Existing Fibre Channel device addressing capability in conjunction with FCIP is viable at this point in time. 6. Manipulation of N_Port ID's as specified in iFCP will make debugging/analysis extremely difficult. In summary, FCIP exists today and is well-defined. FCIP provides all of the features necessary to tunnel Fibre Channel over IP networks. Similarly, iSCSI provides the capability for executing the SCSI command set over IP networks. Creating yet another protocol, such as iFCP, is redundant. David Peterson Cisco Systems, Inc (SRBU) Lead Architect - Standards Development Office: 763-398-1007 Cell: 612-802-3299 e-mail: dap@cisco.com Bob Snively Brocade Communications Systems Principal Engineer Office: 408 487 8135 e-mail: rsnively@brocade.com Mark Bakke Cisco Systems, Inc (SRBU) Chief Architect
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