Converged Data Center: FCoE, iSCSI and the Future of Storage Networking

1 © Copyright 2012 EMC Corporation. All rights reserved.

CONVERGED DATA CENTER: FCoE, iSCSI AND THE FUTURE OF STORAGE NETWORKING

David L. Black, Ph.D. Distinguished Engineer


Agenda

Network Convergence

Protocols & Standards

Server Virtualization

Solution Evolution

Conclusion


10Gb Ethernet Converged Data Center

Maturation of 10 Gigabit Ethernet – Replace 1Gb adapters with fewer (start with 2) 10Gb adapters

– Single network simplifies mobility for virtualization/cloud deployments

10 Gigabit Ethernet simplifies infrastructure – Reduces the number of cables and server adapters

– Lowers capital expenditures and administrative costs

– Reduces server power and cooling costs

– Blade servers and server virtualization drive consolidated bandwidth

FCoE and iSCSI both leverage this inflection point

LAN

SAN Single Wire for Network and Storage 10 GbE


Conventional Rack Servers

• Servers connect to LAN, NAS and iSCSI SAN with NICs

• Servers connect to FC SAN with HBAs

• Many environments today are still Gigabit Ethernet

• Multiple server adapters, higher power/ cooling costs – Separate storage network (incl. iSCSI)

Rack-mount servers

Ethernet Fibre Channel

Ethernet LAN

Gigabit Ethernet

Gigabit Ethernet NICs

Storage

Fibre Channel SAN

Fibre Channel HBAs

Gigabit Ethernet

iSCSI SAN

Note: NAS is part of the converged approach. Everywhere that Ethernet or 10Gb Ethernet is used in this presentation, NAS can be considered part of the unified storage solution


Agenda

• Network Convergence

• Protocols & Standards

• Server Virtualization

• Solution Evolution

• Conclusion


iSCSI Introduction

Transport storage (SCSI) over standard Ethernet – Reliability through TCP

More flexible than FC due to IP routing

Good performance

iSCSI has thrived – Especially where the server, storage and network

administrators are the same person

Link

IP

TCP

iSCSI

SCSI

IP Network


iSCSI Introduction (continued)

Standardized in 2004: IETF RFC 3720 – Stable: No major changes since 2004

– iSCSI Corrections and Clarifications: IETF RFC 5048 (2007)

– Now underway: consolidated spec, minor updates

iSCSI Session: One Initiator and one Target – Multiple TCP connections allowed in a session

Important iSCSI additions to SCSI – Immediate and unsolicited data to avoid round trip

– Login phase for connection setup

– Explicit logout for clean teardown


iSCSI Read Example

Optimization: Good status can be included with last “Data in” PDU

Command Complete

Receive Data

SCSI Read Command

Initiator Target

Status

Data in PDU

Target Data in PDU

Data in PDU


iSCSI Write Example

Optimization: Immediate and/or unsolicited data avoids a round trip

Status

Initiator

R2T

Target

SCSI Write Command

Ready to Transmit (R2T)

Command Complete

Receive Data

Receive Data

Data out PDU

Data out PDU

Data out PDU

Data out PDU


CRC Ethernet Header

IP TCP iSCSI

iSCSI Encapsulation

Delivery of iSCSI Protocol Data Unit (PDU) for SCSI functionality (initiator, target, data read/write, etc.)

Provides IP routing capability so packets can find their way through the network

Reliable data transport and delivery (TCP Windows, ACKs, ordering, etc.) Also demux within node (port numbers)

Provides physical network capability (Cat 6, MAC, etc.)

Data


FCoE: Why a New Option for FC?

FC: large and well managed installed base – Leverage FC expertise / investment

– Other convergence options not incremental for existing FC

Data Center solution for I/O consolidation

Leverage Ethernet infrastructure and skill set

FCoE allows an Ethernet-based SAN to be introduced into an FC-based Data Center

without breaking existing administrative tools and workflows


FCoE Extends FC on a Single Network

Network Driver

FC Driver

Converged Network Adapter

Server sees storage traffic as FC

FC network

FC storage

Ethernet Network

FCoE Switch

Lossless Ethernet SAN sees host as FC

Ethernet FC


FCoE Frames

FC frames encapsulated in Layer 2 Ethernet frames – No TCP, Lossless Ethernet required

– No IP routing

1:1 frame encapsulation – FC frame never segmented across multiple Ethernet frames

Requires at least Mini Jumbo (2.5k) Ethernet frames – Max FC payload size: 2180 bytes

– Max FCoE frame size: 2240 bytes

Eth

ern

et

Head

er

FC

oE

H

ead

er

FC

H

ead

er

FC Payload

CR

C

EO

F

FC

S

FC Frame


FCoE Initialization Ethernet is more than a cable

Native FC link: Optical fiber has 2 endpoints (simple) – Discovery: Who’s at the other end?

– Liveness: Is the other end still there?

FCoE virtual link: Ethernet LAN or VLAN, 3+ endpoints possible – Discovery: Choice of FCoE switches

– Liveness: FCoE virtual link may span multiple Ethernet links ▪ Single link liveness check isn’t enough, where’s the problem?

FCoE configuration: Do mini jumbo (or larger) frames work?

FIP: FCoE Initialization Protocol – Discover endpoints, create and initialize virtual link with FCoE switch

– Mini jumbo frame support: Large frame is part of discovery

– Periodic LKA (Link Keep Alive) messages after initialization


FCoE Switch Discovery Step 1: FIP Solicitation

FCoE/FC Switches

DCB Ethernet FC SAN

Select FCoE VLAN first (pre-config or FIP)

Multicast Solicitation: Server can discover multiple switches

Solicitation identifies Server (FC WWN for FCoE CNA)

– CNA = Converged Network Adapter (FCoE analog of HBA)

– Switch chooses servers to respond to (default: respond to all)

Solicitation

Server


FCoE Switch Discovery Step 2: FIP Advertisement

FCoE/FC Switches

DCB Ethernet FC SAN

Advertisement identifies switch

– Multiple switches may respond, advertisement includes priority

– Server chooses FCoE switch by priority (smallest number wins)

Advertisement padded to max FC frame size: Test mini jumbo frames

Advertisement

Advertisement

Priority = 1

Priority = 25

Server


FIP Switch Discovery Step 3: FIP-based FC Login

FCoE/FC Switches

DCB Ethernet FC SAN

FIP encapsulated FC Login

– Server sends FC Fabric Login (FLOGI) to selected switch

– Switch responds with FC FLOGI ACC (accept) with assigned FCID

All further traffic is standard FC frames (FCoE encapsulated)

Priority = 25

FLOGI

FLOGI ACC

Server

Priority = 1


FCoE and Ethernet Standards –

Fibre Channel over Ethernet (FCoE)

Developed by International Committee for Information Technology Standards (INCITS) T11 Fibre Channel Interfaces Technical Committee

Enables FC traffic over Ethernet

FC-BB-5 standard: June 2009

FC-BB-6 standard in process to expand solution

Data Center Bridging (DCB) Ethernet

Developed by IEEE Data Center Bridging (DCB) Task Group

DCB Ethernet drops frames as rarely as FC

Technology commonly referred to as Lossless Ethernet

IEEE standards: final approval March 2011

DCB: Required for FCoE

DCB: Enhancement for iSCSI

Two complementary standards efforts

Companies working on the standard committees Key participants: Brocade, Cisco, EMC, Emulex, HP, IBM, Intel, QLogic, others


FC-BB-6 – New FCoE features

Direct connection of servers to storage – PT2PT [point to point]: Single cable

– VN2VN [VN_Port to VN_Port]: Single Ethernet LAN or VLAN

Better support for FC fabric scaling (switch count) – Distribute logical FC fabric switch functionality

– Enables every DCB Ethernet switch to participate in FCoE

For more, see Erik Smith’s (EMC E-Lab) presentation: FCoE - Topologies, Protocol, and Limitations

Tues 10:00am and Wed 4:15pm


Lossless Ethernet (DCB)

IEEE 802.1 Data Center Bridging (DCB)

Link level enhancements: 1. Enhanced Transmission Selection (ETS)

2. Priority Flow Control (PFC)

3. Data Center Bridging Exchange Protocol (DCBX)

DCB: network portion that must be lossless – Generally limited to data center distances per link

– Can use long-distance optics, but uncommon in practice

DCB Ethernet provides the Lossless Infrastructure that enables FCoE. DCB also improves iSCSI.


Enhanced Transmission Selection DCB part 1: IEEE 802.1Qaz [ETS] Management framework for link bandwidth

• Priority configuration and bandwidth reservation

– HPC & storage traffic have higher priority

– HPC & storage traffic reserve bandwidth

• Low latency for high priority traffic

– Unused bandwidth available to other traffic

Offered Traffic

t1 t2 t3

10 GE Link Realized Traffic Utilization

3G/s HPC Traffic 3G/s

2G/s

3G/s Storage Traffic 3G/s

3G/s

LAN Traffic 4G/s

5G/s 3G/s

t1 t2 t3

3G/s 3G/s

3G/s 3G/s 3G/s

2G/s

3G/s 4G/s 6G/s


Switch A Switch B

PAUSE and Priority Flow Control DCB part 2: IEEE 802.1Qbb & 802.3bd [PFC]

PAUSE can produce lossless Ethernet behavior – Original 802.3x PAUSE stops all traffic: rarely implemented

New PAUSE: Priority Flow Control (PFC) – Pause per priority level

– No effect on traffic at other priority levels

– Creates lossless virtual lanes

Per priority flow control

– Enable/disable per priority ▪ Only for traffic that needs it

– Better link management than 8-way PAUSE


Data Center Bridging Capability eXchange DCB part 3: IEEE 802.1Qaz (again) [DCBX]

• Ethernet Link configuration (single link)

– Extends Link Layer Discovery Protocol (LLDP)

• Reliably enables lossless behavior (DCB)

– e.g., exchange Ethernet priority values for FCoE and FIP

• FCoE virtual links should not be instantiated without DCBX

FCoE/FC Switches

DCB Ethernet FC SAN

Server

DCBX


Ethernet Spanning Trees and FCoE

Reminder: FCoE is Ethernet only, no IP routing – Ethernet (layer 2) is bridged, not routed

Spanning Tree Protocol (STP): Prevents (deadly) loops

– Elects a Root Switch, disables redundant paths

Causes problems in large layer 2 networks – No network multipathing

– Inefficient link utilization

SiSiSiSi

SiSi SiSi SiSiSiSi SiSi

Root Switch


SiSiSiSi

SiSi SiSi SiSiSiSi SiSi

TRILL – Transparent Interconnection of Lots of Links

Layer 2 routing for Ethernet switches [IP: layer 3] – IS-IS routing protocol for inter-switch Ethernet traffic

– Blocks Spanning Tree Protocol

TRILL encapsulates Ethernet frames – Not used with end systems (NICs)

– NICs: use link teaming/aggregation

All links active


Ethernet Cabling Choices Type /

Connector Cable 1Gb 10Gb 40/100Gb

Copper (10GBase-T) / RJ-45

Cat6 or Cat6a

Most existing cabling (lots of Cat 5e)

Some products on market, but not for FCoE yet. For 10Gb Ethernet:

Cat6 55m Cat6a 100m

Not supported (insufficient bandwidth)

Optical (multimode) / LC

OM2 (orange) OM3 (aqua)

OM4 (aqua)

Rare for Ethernet

Standard for FC

Most backbone deployments are optical.

OM2 82m

OM3 300m

OM4 380m

Expect shift to optical w/ 40/100Gb

OM3 100m

OM4 125m

Copper / SFP+DA (direct attach)

Twinax N/A Low power

5-10m distance (Rack solution)

Different short-distance option (QSFP)

Think of as part of connected equipment


Agenda





• Conclusion


Live Virtual Machine Migration

C: Shared storage: Move VM without

moving stored data

Storage networking: Enabler of shared

storage


virtual switch Hypervisor driver

Storage Drivers and Server Virtualization

NIC NIC FC HBA

FC HBA

vNIC vNIC vSCSI vSCSI

LAN traffic FC traffic

Hypervisor

iSCSI traffic

*iSCSI initiator can also be in the VM (Private Storage)


virtual switch Hypervisor driver

Storage Drivers and Server Virtualization

NIC NIC

vNIC vSCSI vSCSI

Hypervisor

iSCSI traffic

vNIC

*iSCSI initiator can also be in the VM (Private Storage)

FC HBA

FC HBA

CNA

CNA

FCoE follows FC path LAN traffic


Software FCoE and Server Virtualization

NIC NIC FC HBA

FC HBA


Hypervisor

FCoE software in VMs would send traffic through the virtual switch to the NICs

SW FCoE

SW FCoE

Hypervisor driver virtual switch

Virtual Switches in ESX/ESXi

(including Cisco Nexus 1000v) and Hyper-V are not

Lossless (no DCB)

Not a problem for iSCSI, NFS or CIFS

in a VM


Software FCoE and Server Virtualization

NIC NIC FC HBA

FC HBA


Hypervisor

FCoE software in VMs would send traffic through the virtual switch to the NICs

SW FCoE

SW FCoE

Hypervisor driver virtual switch

FCoE works in Hypervisor or CNA (just not in a VM)

CNA

SW FCoE


Agenda





• Conclusion


FCoE and iSCSI

FCoE

FC expertise / install base

FC management

Layer 2 Ethernet

Use FCIP for distance

Ethernet

Leverage Ethernet/IP expertise

10 Gigabit Ethernet

Lossless Ethernet

iSCSI

No FC expertise needed

Supports distance connectivity (L3 IP routing)

Strong virtualization affinity


iSCSI Deployment

10 Gb iSCSI solutions are available

– Traditional Ethernet (recover from dropped packets using TCP) or

– Lossless Ethernet (DCB) environment (TCP still used)

iSCSI: natively routable (IP) – Can use VLAN(s) to isolate traffic

iSCSI solutions: smaller scale than FC

– Larger SANs: usually FC

Ethernet

iSCSI SAN


Converged Network Switch at top of rack or end of row

– Tightly controlled solution – Server 10 GE adapters: CNA or NIC

iSCSI and FCoE via Converged Network Switch

Convergence: Server Phase

FC HBAs 1 Gb NICs

Converged Network Switch

Rack Mount Servers

10 GbE CNAs

FC Attach

Ethernet LAN

Storage

Fibre Channel SAN

Ethernet

FC iSCSI


Convergence: Network Phase

Converged Network Switches move out of rack

Maintains existing SAN and network management

Overlapping admin domains may compel cultural adjustments


10 GbE CNAs

Ethernet LAN

Storage

Fibre Channel SAN

Ethernet

FC

Ethernet Network (IP, FCoE) and CNS

Rack Mount Servers


Convergence at 10 Gigabit Ethernet

Two paths to a Converged Network – iSCSI: purely Ethernet

– FCoE: mix FC and Ethernet (or all Ethernet) ▪ FC compatibility now and in the future

Choose (one or both) on scalability, management, and skill set

10 GbE CNAs

Ethernet LAN

FC & FCoE SAN

iSCSI/FCoE Storage

Rack Mount Servers

Ethernet

FC


Fibre Channel & FCoE attach


EMC and Ethernet

TechBooks (Google: “FCoE Tech Book”) – Fibre Channel over Ethernet (FCoE) and Data Center

Bridging (DCB) Concepts and Protocols

– Fibre Channel over Ethernet (FCoE) and Data Center Bridging (DCB) Case Studies

▪ Includes blade server case studies

Services – Design, Implementation, Performance and Security

offerings for networks

Products – Ethernet equipment for creating Converged Network

Environments


Agenda





• Conclusion


Summary

Converged data centers can be built using 10Gb Ethernet

– Continued use of FC and adoption of FCoE can be flexible due to shared management

– iSCSI solutions work well for all IP/Ethernet networks

10 Gigabit Ethernet solutions are maturing – Active industry participation is creating standards that

allow solutions that can integrate into existing data centers

– FCoE and iSCSI will follow Ethernet roadmap to 40 and 100 Gigabits/sec

Achieving a converged network: Consider technology, processes/best practices and organizational dynamics


Network Virtualization: Background

Each application (or VM) sees its own virtual network,

independent of physical network

VLAN Trunk

Switch Switch

Benefits of Virtual Networks

Common network links with access control properties of separate links. Manage virtual networks instead of

physical networks. Virtual SANs provide similar

benefits for storage area networks.

Virtual Networks

VLAN B VLAN C VLAN A


Network Virtualization: What’s new?

Network version of DOS’s 640k memory limit – Ethernet VLAN tag has only 12 bits!

Not enough for large data centers – Run any workload, anywhere? – Configure every VLAN, everywhere!

New approach: IP-based encapsulation – Encapsulate Ethernet frames in IP – Use IP routing (e.g., OSPF ECMP) to run network – Hypervisor virtual switches can encapsulate for VMs

Example encapsulations: VXLAN, NVGRE – Initially: No DCB Ethernet support (so, no FCoE, initially) – iSCSI, NFS, CIFS all work fine (all use TCP)

Watch this space! – E.g., IETF nvo3 (Network Virtualization Overlays) Working Group


Related Session and Resources

FCoE - Topologies, Protocol, and Limitations – Tuesday 10:00a & Wednesday 4:15p

Birds of a Feather: The Future of Storage Networking – Tuesday 1:30p

Brocade: Storage Networking For the Virtual Enterprise – Tuesday 4:15p

FCoE in the EMC Support Matrix – http://elabnavigator.emc.com

EMC FCoE Videos: Search for “FCoE” on YouTube

EMC FCoE Introduction whitepaper – http://www.emc.com/collateral/hardware/white-papers/h5916-intro-to-

fcoe-wp.pdf

FCoE Blog by Erik Smith (E-Lab) – http://www.brasstacksblog.typepad.com

http://elabnavigator.emc.com/

http://www.emc.com/collateral/hardware/white-papers/h5916-intro-to-fcoe-wp.pdf













http://www.brasstacksblog.typepad.com/


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Converged Data Center: FCoE, iSCSI and the Future of Storage Networking

Technology

emc corporation

gb ethernet

multiple ethernet frames

pdu copyright

fcoe frames fc frames

ethernetbased san

iscsi corrections

nics gigabit ethernet