Network Working Group David Melman Internet Draft Tal Mizrahi Intended status: Informational Marvell Expires: May 2013 Donald Eastlake Huawei November 7, 2012 FCoE over TRILL draft-mme-trill-fcoe-05.txt Abstract Fibre Channel over Ethernet (FCoE) and TRILL are two emerging standards in the data center environment. While these two protocols are seemingly unrelated, they have a very similar behavior in the forwarding plane, as both perform hop-by-hop forwarding over Ethernet, modifying the packet's MAC addresses at each hop. This document describes an architecture for the integrated deployment of these two protocols. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on May 7, 2013. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. Melman, et al. Expires May 7, 2013 [Page 1] Internet-Draft FCoE over TRILL November 2012 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction ................................................. 2 2. Abbreviations ................................................ 3 3. FCoE over TRILL .............................................. 4 3.1. FCoE over a TRILL Cloud ................................. 4 3.2. FCoE over RBridge ....................................... 6 3.2.1. FCRB ............................................... 6 3.2.2. Topology ........................................... 8 3.2.3. The FCRB Flow ..................................... 10 3.2.3.1. Example - ENode to ENode ..................... 10 3.2.3.1.1. Forwarding from A to C - Dense Mode ..... 10 3.2.3.1.2. Forwarding from A to C - Sparse Mode .... 11 3.2.3.2. Example - ENode to Native FC Node ............ 12 3.2.3.3. Example - ENode to ENode with non-FCRB EoR ... 12 3.2.3.4. Example - FCoE Control Traffic through an FCRB 13 4. Security Considerations ..................................... 14 5. IANA Considerations ......................................... 14 6. Acknowledgments ............................................. 14 7. References .................................................. 15 7.1. Normative References ................................... 15 7.2. Informative References ................................. 15 1. Introduction Data center networks are rapidly evolving towards a consolidated approach, where Ethernet is used as the common infrastructure for all types of traffic. Storage traffic was traditionally dominated by the Fibre Channel (FC) protocol suite. At the intersection between these two technologies a new technology was born, Fibre Channel over Ethernet (FCoE), where native Fibre Channel (FC) packets are encapsulated with an FCoE encapsulation over an Ethernet header. FCoE is specified in [FC-BB-5] (A future version of FCoE is under development and is expected to be specified in a document to be referred to as FC-BB-6; however, this is a work in progress and beyond the scope of this document.) Melman, et al. Expires May 7, 2013 [Page 2] Internet-Draft FCoE over TRILL November 2012 Traffic between two FCoE end nodes (ENodes) is forwarded through one or more FCoE Forwarders (FCF). An FCF takes a forwarding decision based on the Fibre Channel destination ID (D_ID), and enforces security policies between ENodes, also known as zoning. Once an FCF takes a forwarding decision, it modifies the source and destination MAC addresses of the packet, to reflect the path to the next hop FCF or ENode. An FCoE virtual link is an Ethernet link between an ENode and an FCF, or between two FCFs. An FCoE virtual link may traverse one or more Layer 2 bridges. FCFs use a routing protocol called Fabric Shortest Path First (FSPF) to find the optimal path to each destination. An FCF typically has one or more native Fibre Channel interfaces, allowing it to communicate with native Fibre Channel devices, e.g., storage arrays. TRILL [RFCTRILL] is a protocol for transparent least cost routing, where RBridges forward traffic to their destination based on a least cost route, using a TRILL encapsulation header. RBridges route TRILL- encapsulated packets based on the Egress RBridge Nickname in the TRILL header. An RBridge routes a TRILL-encapsulated packet after modifying its MAC addresses to reflect the path to the next-hop RBridge, and decrementing a Hop Count field. TRILL and FCoE bear a strong resemblance in their forwarding planes. Both protocols take a routing decision based on protocol addresses above Layer 2, and modify the Ethernet MAC addresses on a per-hop basis. Each of the protocols uses its own routing protocol rather than using any type of bridging protocol such as spanning tree protocol [802.1Q] or the Shortest Path Bridging protocol [802.1aq]. FCoE and TRILL are both targeted at the data center environment, and their concurrent deployment is self-evident. This document describes an architecture for the integrated deployment of these two protocols. 2. Abbreviations DCB Data Center Bridging ENode FCoE Node such as server or storage array EoR End of Row FC Fibre Channel FCF Fibre Channel Forwarder FCoE Fibre Channel over Ethernet Melman, et al. Expires May 7, 2013 [Page 3] Internet-Draft FCoE over TRILL November 2012 FCRB Fibre Channel forwarder over RBridge FIP FCoE Initialization Protocol FSPF Fabric Shortest Path First LAN Local Area Network RBridge Routing Bridge SAN Storage Area Network ToR Top of Rack TRILL Transparent Interconnection of Lots of Links WAN Wide Area Network 3. FCoE over TRILL 3.1. FCoE over a TRILL Cloud The simplest approach for running FCoE traffic over a TRILL network is presented in Figure 1. The figure illustrates a TRILL-enabled network, where FCoE traffic is transparently forwarded over the TRILL cloud. The figure illustrates two ENodes, a Server and an FCoE Storage Array, an FCF, and a native Fibre Channel SAN connected to the FCF. FCoE traffic between the two ENodes is sent from the first ENode over the TRILL cloud to the FCF, and then back through the TRILL cloud to the second ENode. Melman, et al. Expires May 7, 2013 [Page 4] Internet-Draft FCoE over TRILL November 2012 +---+ | |_________ | | \ ___ _ +---+ \/ \_/ \__ _ __ FCoE Storage _/ \ / \_/ \_ Array / TRILL / +---+ \_ \ (ENode A) \_ Cloud /________| |____/ SAN _/ / \ | | \__ _/ \__/\_ ___/ +---+ \_/ +---+ / \_/ FCF | |________/ | | +---+ Server (ENode B) Figure 1 The "Separate Cloud" Approach The configuration in Figure 1 separates the TRILL cloud(s) and the FCoE cloud(s). The TRILL cloud routes FCoE traffic as standard Ethernet traffic, and appears to the ENodes and FCF as an Ethernet LAN. FCoE traffic routed over the TRILL cloud includes FCoE data frames, as well as FCoE control traffic, including FCoE Initialization Protocol (FIP) frames. To eliminate frame loss due to queue overflow, the switches in any TRILL Cloud used with FCoE would likely implement and use the relevant DCB protocols [TRILLDCB]. The main drawback of the Separate Cloud approach is that RBridges and FCFs are separate nodes in the network, resulting in more cabling and boxes, and communication between ENodes usually requires two TRILL cloud traversals with twice as many hops. As mentioned above, data center networking is converging towards a consolidated and cost effective approach, where the same infrastructure and equipment is used for both data and storage traffic, and where high efficiency and minimal number of hops are important factors when designing the network topology. The Separate Cloud approach is presented as a background and motivation. The next section introduces an alternative approach with a higher level of integration. Melman, et al. Expires May 7, 2013 [Page 5] Internet-Draft FCoE over TRILL November 2012 3.2. FCoE over RBridge 3.2.1. FCRB Rather than the Separate Cloud approach discussed in the previous subsection, an alternate approach is presented, where each switch incorporates both an FCF entity and an RBridge entity. This consolidated entity is referred to as FCoE-forwarder-over-RBridge (FCRB). Figure 2 illustrates an FCRB, and its main building blocks. An FCRB can be functionally viewed as two independent entities: o An FCoE Forwarder (FCF) entity. o An RBridge entity. The FCF entity is connected to one of the ports of the RBridge, and appears to the RBridge as a native Ethernet host. A detailed description of the interaction between the layers is presented in Section 3.2.3. Note: the term "FCF" is used in this document slightly differently than defined in [FC-BB-5], to emphasize the concept that an FCRB is logically similar to an RBridge cascaded to an FCF. In the [FC-BB-5] terminology, an FCRB would be referred to as an FCF, and the "FCF" building block in Figure 2 would be referred to as a FC switching element. Melman, et al. Expires May 7, 2013 [Page 6] Internet-Draft FCoE over TRILL November 2012 +-------------------+ |FCRB | | +-----------+ | Native FC | | FCF |------ Interface | +-----+-----+ | | | | | +-----+-----+ | | | RBridge | | | +-+-+---+-+-+ | | | | | | | +-----|-|---|-|-----+ FCoE/ / | | | +---+ Ethernet / / | | FCoE / Ethernet | |___________________/ / | | over TRILL ___ _ | | / | | / \_/ \__ +---+ / | \_____________ _/ \ FCoE Storage / \_______________/ TRILL / Array / \_ Cloud / (ENode A) / / \ / \__/\_ ___/ +---+ / \_/ | |______________/ | | +---+ Server (ENode B) Figure 2 FCRB Entity in the Network The FCRB entity maintains layer independence between the TRILL and FCoE protocols, while enabling both protocols on the same network. It is noted that FCoE traffic is always forwarded through an FCF, and cannot be forwarded directly between two ENodes. Thus, FCoE traffic between ENodes A and B in the topology in Figure 1 is forwarded through the path ENode A-->TRILL cloud-->FCF-->TRILL cloud-->ENode B As opposed to the topology in Figure 1, the FCF in Figure 2 is adjacent to ENodes A and B. In Figure 2 the FCRB is connected to ENodes A and B, and functions as the edge RBridge that connects these two nodes to the TRILL cloud, as well as the FCF that forwards Melman, et al. Expires May 7, 2013 [Page 7] Internet-Draft FCoE over TRILL November 2012 traffic between these two nodes. Thus, traffic between A and B in the topology in Figure 2 is forwarded through the path ENode A-->FCRB-->ENode B Hence, the usage of FCRB entities allows TRILL and FCoE to use common infrastructure and equipment, as opposed to the Separate Cloud topology presented in Figure 1. 3.2.2. Topology The network configuration illustrated in Figure 3 shows a typical topology of a data center network. Servers are hierarchically connected through Top-of-Rack (ToR) switches, also known as access switches, and each set of racks is aggregated through an End-of-Row (EoR) switch. The EoR switches are aggregated to the Core switches, which may be connected to other clouds, such as an external WAN or a native FC SAN. Melman, et al. Expires May 7, 2013 [Page 8] Internet-Draft FCoE over TRILL November 2012 _ __ _ __ / \_/ \_ / \_/ \_ \_ \ \_ \ .... / SAN _/ / WAN _/ \__ _/ \__ _/ \_/ \_/ | | | | | | +------+ +------+ Core | | | | FCoE over | | | | RBridge | | | | (FCRB) +------+ +------+ | \___ ___/ | | \ / | | \/ | EoR +----+_______/\_______+----+ FCoE over | | | | RBridge | | | | (FCRB) +----+ +----+ / \ / \ / \ / \ ToR +---+ +---+ +---+ +---+ FCoE over | | | | | | | | RBridge | | | | | | | | (FCRB) +---+ +---+ +---+ +---+ / \ / \ / \ / \ / \ / \ / \ / \ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ Servers/ | | | | | | | | | | | | | | | | ENodes +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ A B C D E F G H Figure 3 FCoE over RBridge Topology Note that in the example in Figure 3 all the ToR, EoR and core switches are FCRB entities, but it is also possible for some of the network nodes to be pure RBridges, creating a topology where FCRBs are interconnected through TRILL clouds. Melman, et al. Expires May 7, 2013 [Page 9] Internet-Draft FCoE over TRILL November 2012 3.2.3. The FCRB Flow 3.2.3.1. Example - ENode to ENode FCoE traffic sent between two ENodes, A and B in Figure 3, is transmitted through the ToR FCRB, since A and B are connected to the same ToR. Traffic between A and C must be forwarded through the EoR FCRB. The FCoE jargon distinguishes between two deployment modes: o Sparse mode: an FCoE packet sent between two FCFs may be forwarded over several hops of a Layer 2 network, allowing the underlying Layer 2 network to determine the path between the two FCFs. o Dense mode: each node along the path between two FCFs is also an FCF, and the network is configured such that the forwarding decision at each hop is taken at the FCF layer, allowing the path between the two FCFs to be based on the FSPF routing protocol. Figure 4 illustrates the traffic between ENodes A and C that are not connected to the same ToR. The following two subsections describe the forwarding procedure in the Dense mode and in the Sparse mode, respectively. +--------+ +--------+ +--------+ +--------+ +--------+ | FCoE |.....| FCF |.....| FCF |.....| FCF |.....| FCoE | | ENode | +--------+ +--------+ +--------+ | ENode | | | |RBridge |.....|RBridge |.....|RBridge | | | +--------+ +--------+ +--------+ +--------+ +--------+ |Ethernet|<===>|Ethernet|<===>|Ethernet|<===>|Ethernet|<===>|Ethernet| +--------+ +--------+ +--------+ +--------+ +--------+ Server ToR 1 EoR ToR 2 FCoE Storage ENode A FCRB FCRB FCRB Array ENode C Figure 4 Traffic between two ENodes - Example 3.2.3.1.1. Forwarding from A to C - Dense Mode o FCoE traffic from A is sent to the ToR over the Ethernet interface. The destination MAC address is the address of the FCF entity at the ToR. o ToR 1: Melman, et al. Expires May 7, 2013 [Page 10] Internet-Draft FCoE over TRILL November 2012 o The packet is forwarded to the FCF entity at the ToR. Thus, forwarding between A and the FCF at the ToR is analogous to forwarding between two Ethernet hosts. o The FCF entity at the ToR takes a forwarding decision based on the FC addresses. This decision is based on the FSPF routing protocol at the FCF layer, forwarding the packet to the FCF entity in the EoR. o The FCF then updates the destination MAC address of the packet to the address of the EoR FCF. o The packet is forwarded to the RBridge entity, where it is encapsulated in a TRILL header, and sent to the RBridge at the EoR over a single hop of the TRILL network. o The RBridge entity in the EoR FCRB, acting as the egress RBridge, decapsulates the TRILL header and forwards the FCoE packet to the FCF entity. From this point the forwarding process is similar to the one described above for the ToR. o A similar forwarding process takes place at the next hop ToR FCRB, where the FCRB finally forwards the FCoE packet to the target ENode C. 3.2.3.1.2. Forwarding from A to C - Sparse Mode o Traffic is forwarded to ToR 1, as described in Section 3.2.3.1.1. o The FCF in ToR 1, based on an FSPF forwarding decision, forwards the packet to the FCF in ToR 2. The destination MAC address of the FCoE packet is updated, reflecting the FCF in ToR 2. The RBridge entity in ToR 2 adds a TRILL encapsulation, with an egress RBridge nickname representing ToR 2. o The packet reaches the EoR. The RBridge entity in the EoR routes the packet to the RBridge entity in ToR 2. o The packet reaches ToR 2, and from this point on the process is identical to the one described in Section 3.2.3.1.1. Melman, et al. Expires May 7, 2013 [Page 11] Internet-Draft FCoE over TRILL November 2012 3.2.3.2. Example - ENode to Native FC Node +--------+ +--------+ +--------+ +---------+ +--------+ | FCoE |.....| FCF |.....| FCF |.....| FCF |.....| FC | | ENode | +--------+ +--------+ +----+----+ |protocol| | | |RBridge |.....|RBridge |.....| RB | | | stack | +--------+ +--------+ +--------+ +----+ FC | | | |Ethernet|<===>|Ethernet|<===>|Ethernet|<===>|Eth | |<===>| | +--------+ +--------+ +--------+ +----+----+ +--------+ Server ToR EoR Core Native FC ENode FCRB FCRB FCRB Storage Array Figure 5 Example Traffic between ENode & Native FC Storage Array Figure 5 illustrates a second example, where traffic is sent between an ENode and an FC Storage Array, following the network topology in Figure 3. o FCoE traffic from the ENode is sent to the ToR over the Ethernet interface. The forwarding process through the ToR FCRB and through the EoR is similar to the corresponding steps in Section 3.2.3.1. o When the packet reaches the core FCRB, the egress RBridge entity decapsulates the TRILL header and forwards the FCoE packet to the FCF entity. The packet is then forwarded as a native FC packet through the FC interface to the native FC node. 3.2.3.3. Example - ENode to ENode with non-FCRB EoR The example illustrated in Figure 6 is similar to the one shown in Figure 4, except that the EoR is an RBridge rather than an FCRB. Melman, et al. Expires May 7, 2013 [Page 12] Internet-Draft FCoE over TRILL November 2012 +--------+ +--------+ +--------+ +--------+ | FCoE |.....| FCF |....................| FCF |.....| FCoE | | ENode | +--------+ +--------+ +--------+ | ENode | | | |RBridge |.....|RBridge |.....|RBridge | | | +--------+ +--------+ +--------+ +--------+ +--------+ |Ethernet|<===>|Ethernet|<===>|Ethernet|<===>|Ethernet|<===>|Ethernet| +--------+ +--------+ +--------+ +--------+ +--------+ Server ToR 1 EoR ToR 2 FCoE Storage ENode A FCRB FCRB FCRB Array ENode C Figure 6 Traffic between two ENodes - Example An FCoE packet sent from A to C is forwarded as follows: o The packet is sent to the FCF in ToR 1, as in the previous example. o The FCF in ToR 1 takes a forwarding decision based on the FC addresses, and forwards the packet to the next hop FCF, which resides in ToR 2. This forwarding decision is taken at the FCF layer, and is based on the FSPF routing protocol. o The packet is then forwarded to the RBridge entity in ToR 1, where it is encapsulated in a TRILL encapsulation, and forwarded to the RBridge at ToR 2. The packet is routed over the TRILL cloud through the RBridge at the EoR. The path through the TRILL cloud is determined by TRILL's IS-IS routing protocol. o Once the packet reaches ToR 2, it is forwarded in a similar manner to the description in Section 3.2.3.1. This example demonstrates that it is possible to have a hybrid network, where some of the nodes are FCRBs, and some of the nodes are RBridges. The forwarding procedure in this example is somewhat similar to the sparse-mode forwarding described in Section 3.2.3.1.2. 3.2.3.4. Example - FCoE Control Traffic through an FCRB The previous subsections focused on the data plane, i.e., storage data exchanges transported over an FCoE encapsulation. FCoE also requires control and management traffic that is used for initializing sessions (FIP), distributing routing information (FSPF), and fabric administration and management. Melman, et al. Expires May 7, 2013 [Page 13] Internet-Draft FCoE over TRILL November 2012 The FCoE Initialization Protocol (FIP) uses Ethernet frames with a dedicated Ethertype, allowing the FCF to distinguish it from other traffic. FIP uses both unicast and multicast traffic. The following example describes the forwarding scheme of a multicast FIP packet sent through the network depicted in Figure 4: o ENode A generates a multicast frame to a multicast MAC address representing all the FCFs (All-FCF-MAC). o The packet is forwarded to the ToR FCRB node. The RBridge entity forwards a copy of the packet to its FCF entity, and also sends the packet through the TRILL cloud as a multicast TRILL encapsulated packet. o Each of the FCRBs in turn receives the packet, forwards a copy to its FCF entity, as well as forwarding the packet through the TRILL network, allowing all the FCFs to receive the packet. While FIP packets have a dedicated Ethertype and frame format, other types of FCoE control and management frames use the same FCoE encapsulation as FCoE data traffic. Thus, the forwarding scheme for such control traffic is similar to the examples described in the previous subsections, with the exception that these frames can be sent between ENodes, between FCFs, or between ENodes and FCFs. 4. Security Considerations For general TRILL Security Considerations see [RFCTRILL]. For general FCoE Security Consideration see Annex D of [FC-BB-5]. There are no additional security implications imposed by this document. 5. IANA Considerations There are no IANA actions required by this document. RFC Editor: please delete this section before publication. 6. Acknowledgments The authors gratefully acknowledge Ayandeh Siamack and David Black for their helpful comments. The authors also thank the T11 committee for reviewing the document, and in particular Pat Thaler and Joe White for their useful inputs. Melman, et al. Expires May 7, 2013 [Page 14] Internet-Draft FCoE over TRILL November 2012 This document was prepared using 2-Word-v2.0.template.dot. 7. References 7.1. Normative References [RFCTRILL] Perlman, R., Eastlake, D., Dutt, D., Gai, S., Ghanwani, A., "Routing Bridges (RBridges): Base Protocol Specification", RFC 6325, July 2011. [FC-BB-5] ANSI INCITS 462: Information Technology - Fibre Channel - Backbone - 5 (FC-BB-5). 7.2. Informative References [802.1Q] "IEEE Standard for Local and metropolitan area networks - Virtual Bridged Local Area Networks", IEEE Std 802.1Q-2011, May 2011. [802.1aq] "IEEE Standard for Local and metropolitan area networks - Media Access Control (MAC) Bridges and Virtual Bridged Local Area Networks - Shortest Path Bridging", IEEE Std 802.1aq-2012, June 2012. [TRILLDCB] Eastlake, D., Wadekar, M., Ghanwani, A., Agarwal, P., Mizrahi, T., "TRILL: Support of IEEE 802.1Qbb, 802.1Qaz, and Congestion Notification", draft- eastlake-trill-rbridge-dcb, work in progress, 2012. Authors' Addresses David Melman Marvell 6 Hamada St. Yokneam, 20692 Israel Email: davidme@marvell.com Melman, et al. Expires May 7, 2013 [Page 15] Internet-Draft FCoE over TRILL November 2012 Tal Mizrahi Marvell 6 Hamada St. Yokneam, 20692 Israel Email: talmi@marvell.com Donald Eastlake 3rd Huawei USA R&D 155 Beaver Street Milford, MA 01757 USA Phone: +1-508-333-2270 EMail: d3e3e3@gmail.com Melman, et al. Expires May 7, 2013 [Page 16]