FCToposAddrs

7/27/2019 FCToposAddrs

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2003 Brocade Communications Systems,

Incorporated.

Revision0.1_FC101_2003

Fibre Channel Topologies,

Terminology and Addressing

Brocade

Product Training


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2003 Brocade Communications Systems,Incorporated.


After completing this module, attendees should be able to:

Identify FC Topologies

Discuss and Review key FC Terminology

Discuss FC Addresses

Course Objectives


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FC Topologies

FC Terminology

FC Addressing

World Wide Names (WWNs)

Port Identifiers (PIDs), also called 24-bit, S_ID, or D_ID addresses

Well-known Addresses

Topics


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Fibre Channel Topologies

Three kinds of Fibre Channel Topologies

Point-to-Point (Pt to Pt) - Allows two devices to talk

Arbitrated Loop - Allows 126 devices to talk, Arbitrated Loop

Physical Address (AL_PA) 00, is reserved for the Fabric Loop Port(FL_Port)

Switched Fabric Allows 16 Million theoretical devices to talk

Point-to-Point is limited to two devices but they can talk at greater distancesthan SCSI allows.

Arbitrated Loop is limited to 126 devices in a blocking architecture (plus onefor FL_Port). Without a switch only two of these devices can talk at a time, all

others are blocked until those two are done. An arbitrated loop attached to aswitch allows queuing into and out of the port where the loop is attached. Theembedded port will take one AL_PA, so on a Brocade switch port there are 125available AL_PAs.

Switched fabric can theoretically allow 16 million nodes to talk (16^6 Thereare 6 Port Identifier (PID) slots with 16 hex choices per slot)). The committeereserves million of these addresses for well known addresses and testingpurposes.


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Two devicesconnectedtogether

Fibre Channel Topology Cont.Point to Point (Pt to Pt)

5

Point-to-point is a simple topology that allows bi-directional communicationbetween two nodes, in this case a storage system and a server. This topologyis very similar with SCSI direct attached except it is faster and supports longerdistance. Point-to-point, like all SAN topologies, benefits from a longer reachwith fiber optic connections. It is clear that a point-to-point topology has itslimitations, yet it has proven to be a fast and powerful method for connecting

storage devices/arrays directly to the servers.


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Theoretically up to 126devices on a shared

media for small systemsat reduced cost andreducedperformance level

Requires a port tosuccessfully arbitrateprior to establishing acircuit to send and/or

receive frames

Fibre Channel Topology Cont.Fibre Channel Arbitrated Loop (FCAL)

6

The arbitrated loop is a ring topology where each node passes data to itsadjacent nodes. Like an IBM Token Ring network, the SAN hub arbitratesrequests for data to make optimum use of the available bandwidth. In anArbitrated Loop configuration, the transmitter of each node is connected to thereceiver of the next node. In order to send data from one node to another,devices must arbitrate for access to the loop. The initiating device arbitratesfor control of the loop. Once the device wins arbitration, it then opens acommunication session with the target and sends the data. The initiating nodeengages in a Point-to-Point connection with the recipient node. Only oneconnection can be established at a time. When the data transfer is completed,the initiator closes the session and releases control of the loop, allowing otherdevices to arbitrate for the loop. Currently, the maximum bandwidth is 100MB/sec

Fibre Channel Arbitrated Loop - the transmit of each node is connected to thereceive of the next node.

Reduced costpath into FC SCSI Replacement

Requires FC Hub technology

Easy for vendors to develop

Difficult for customers to deploy

Limited possible nodes (126) plus the Loop Master (FL_Port)

Lower overall throughput - 100MB maximum bandwidth

Limited any to any connectivity - nodes on the loop have to arbitratefor control of the loop in order to be able to communicate with a targetdevice on the loop. While this communication is happening all otherdevices are waiting to get their turn.


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FC Arbitrated Loop TopologyAn FCAL attached to a switch

Hub

Switch

FL

NLNL

NL

NL

NLNLNL

N

F

N

F

This diagram shows an example of a FCAL loop attached to a switch

Communication can take place between:

1. Devices on the loop.

2. A device on the loop and a device attached to the switch. (A host onthe loop could access data from the Fabric-attached storage.)

3. A device attached to the switch and a device on the loop. (The Fabric-attached host could write data to the storage on the loop.)

Devices on the loop can either be public (capable of doing a Fabric Logincalled a FLOGI) or private (not capable of doing a Fabric Login called aFLOGI )

If the devices are private, the switch will probe them and get them into theFabric Name Server if possible (private host devices do not accept probes).The FL_Port that the private loop device is attached to will also providetranslation of Fabric 24-bit addresses and FCAL 8-bit addresses.


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Arbitrated Loop Physical AddressAL_PA

Arbitrated Loop Physical Address (AL_PA) needed to

communicate

An 8-bit address assigned to each device on loop

Maximum of 126 AL_PAs attached to FL_Port

AL_PA 00 reserved for FL_Port

These 127 AL_PAs are a unique set out of the possible 256

bit patterns

The lower the AL_PA, the higher the priority

Arbitrated Loop uses 8 bits to identify each of the devices on a loop. This is thePhysical Address for the device and is known as the AL_PA. The protocol allowsfor 127 devices, so 126 unique AL_PAs need to exist for the NL Nodes AL_PA 00reserved for the Switch FL_Port.

Using certain bit combinations can create disparity errors so the 126 AL_PAsavailable for the NL_Ports are a fixed set. The next slide shows the valid AL_PA

table.

Not all AL_PAs are created equal. In arbitrating for control of the loop, thedevice with the highest priority succeeds. The lower the AL_PA assigned, thehigher the priority for the device in the loop.

Arbitrated Loop devices receive an AL_PA during the loop initialization process,and are described in later slides.


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Valid AL_PAs

E0

E1

E2

E4

E8

EF

D1

D2

D3

D4

D5

D6

D9

DA

DC

C3

C5

C6

C7

C9

CA

CB

CC

CD

CE

B1

B2

B3

B4

B5

B6

B9

BA

BC

A3

A5

A6

A7

A9

AA

AB

AC

AD

AE

90

97

98

9B

9D

9E

9F

80

81

82

84

88

8F

71

72

73

74

75

76

79

7A

7C

63

65

66

67

69

6A

6B

6C

6D

6E

51

52

53

54

55

56

59

5A

5C

43

45

46

47

49

4A

4B

4C

4D

4E

31

32

33

34

35

36

39

3A

3C

23

25

26

27

29

2A

2B

2C

2D

2E

10

17

18

1B

1D

1E

1F

00

01

02

04

08

0F

Lowest

priority

Highest

priority

The 8-bit addresses notshown in this table will never be used as anAL_PA for a device on the loop (03, 05, 06, etc.).

The AL_PA for the FL_Port on a public loop will always be 00.


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Loop InitializationWhat can cause it?

Power On /Power On Reset

Entering/Leaving a participating mode

Loop failure

Arbitration Wait timeout

Selective Reset LI P

Power On / Power On Reset

Loop Initialization occurs when a port is powered on or was given anequivalent reset.

Enter/Leave Participating Mode

A port in nonparticipating mode may, after a port dependent timeout, attemptto become a participating port. If the port is successful in obtaining an AL_PA,it can participate in loop operations after initialization completes. If the port isunsuccessful it remains in nonparticipating mode.

A port already in participating mode can change to nonparticipating mode. Itrelinquishes the AL_PA it was assigned and makes it available for other portsto acquire.

Loop Failure

This may have occurred due to a port on the loop failing, being powered off,or a physical connection in the loop is broken.

Arbitration Wait Timeout

Excessive unfairness or a hung port may cause a port to not win arbitration.

The port may use loop initialization to clear this condition.

Selective reset LIP

Causes the ports on the loop to do a vendor-unique reset. Usually, this isequivalent to a power-on reset.


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Loop InitializationWhat happens?

Loop initialization begins by a port transmitting LIPs

All loop activity is suspended

All ports enter the Open-Initializing state

One port is selected as Master

Ports are assigned an AL_PA

Positional AL_PA map of loop is built (if supported)

All ports return to Monitoring state

Normal loop operations resume

The Loop Initialization Primitive (LIP) is used to begin the process and suspendany activities if the loop is currently active. Receiving ports recognize the loopinitialization process when at least three consecutive LIPs are received. Theport enters the Open-Init state and continues to retransmit the LIPs to thenext port on the loop.

Once all the ports are in the Open-Init state, a series of frames are passedaround the loop to determine a loop master, assign an AL_PA to each deviceon the loop and report the position of each device (optional).

The loop returns to the monitoring state and normal loop operations canresume.


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Loop InitializationSequence of Events

LIPs (Loop Initialization Primitive Sequence)

LISM ( Select Master)

LIFA ( Fabric Assigned)

LIPA ( Previous Assigned)

LIHA ( Hardware Assigned)

LISA ( Software Assigned)

LIRP ( Report Position (if supported))

LILP ( Loop Position (if supported))

CLS (Close Primitive Signal )

Initialization is complete Public loop devices can log into the Fabric!

FC

Frames

LIP and CLS are Ordered Sets used to indicate states or events. Ordered Sets arespecial four-character combinations that have special meaning in Fibre Channel.

A LIP is a Primitive Sequence Ordered Set. Primitive Sequences are used toindicate states or conditions and are normally transmitted continuously untilsomething causes the current state to change.

CLS is a Primitive Signal Ordered Set. Primitive Signals are used to indicate eventsor actions and are normally transmitted once.

LISM is a frame that each device enters on the loop. It will determine the devicethat becomes the loop master. This port controls the rest of the loop initializationprocess.

LIFA, LIPA, LIHA, LISA are frames passed around the loop for devices to have theirAL_PA assigned.

LIRP and LILP are also frames that are passed around the loop but are used toallow the reporting of the position of the device on the loop. This is an optionalstep in the loop initialization process. It allows any device to learn not only theAL_PA of all the devices but the order in which they occur on the loop.

There are different types of LIP sequences:LI P( F7, F7) - loop port in initialization state does not have an AL_PA

LI P( F7, AL_PS) - loop port identified by AL_PS requests loop initialization

LI P( F8, F7) - loop port, without a valid AL_PA (thus the F7), in the initializing

state, requests loop initialization due to loop failure

LI P( F8, AL_PS) - loop port identified by AL_PS detects loop failure

LI P(AL_PD, AL_PS) - used to perform a vendor specific reset at loop port AL_PD,

AL_PS port originated the request


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Fibre Channel Topology Cont.Switched Fabric

Switch Fabric Topology:

Highest performance level

High scalability Good fault isolation

Embedded management andservices

Up to 239 unique domains(switches) with:

Unique switch names

Unique IP addresses

Samefabric.ops 1

parameters

Switched fabric - An extensive storage network in which large numbers ofservers and storage systems are connected using Fibre Channel switches.Switches can be cascaded and combined with loops to create highly interwovennetworks known as fabrics. Fortunately, these complex solutions can be keptunder control by software that takes advantage of SAN management capabilitiesbuilt directly into the fabric.

Switched SAN Fabrics Fullest FC Network topology

Require FC Switch technology

Difficult for vendors to develop

Easy for customers to deploy

Maximum possible nodes (16 Million or 224 theoretical)

Higher overall aggregate throughput - each connection to the switch is 100 or100 MB per second.

Enterprise any to any connectivity - Any device on the switch/Fabric cancommunicate with any other device on the Fabric

Scaling is easy as switches can be connected together in various topologies.The result is a Fibre Channel Fabric.

Footnote 1: fabric.ops parameters contain configurable parameters that need tobe the same on all Fabric switches, examples include:

f abr i c. ops. dat aFi el dSi ze: 2112

f abr i c. ops. mode. pi dFor mat : 1


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Fibre Channel Terminology Review

Terminology will be defined throughout the course bu t some basicswould be helpful:

Fabric A Fabric is a connection of Fibre Channel switchesand/or devices capable of routing frames using only a destinationidentifier (D_I D) A Fabric is commonly pictured as a cloud

The term Fabric can also refer to the physical switches, or to a set of globalsoftware components such as the routing tables, zoning configuration, andname server.


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Tx

RxNx_Port A

Tx

Rx

Nx_Port B

Node I Node II

Fibre Channel Terminology Cont.

Nodes Transmit and Receive information via one or more portswhich provide the physical connection(s) for the nodes

Ports Separate transmit (t x) and receive (r x) functions

Tx encodes and transforms data to serial format

Rx recovers clock from serial data received, decodes and de-serializes the data

Each Node has a unique 64-bit address called Node World WideName. The format of this 64-bit identifier along with the format forthe port on this nodes 64-bit identifier are specified by IEEE.

Each Port also has a unique 64-bit address called Port World WideName. N_Ports are node ports that can either attach to other N_Ports

or to Fabric Ports (F_Port). Nx_Ports could either be N_Ports (x notused) or NL_Ports (Node Loop Ports) used in the Arbitrated Looptopology.

Each Nx_Port also has a 24-bit address also referred to as: portidentifier (PID), Source Identifier (S_ID) when its used as a source inFC communications and Destination Identifier (D_ID) when its used asa destination address in FC communications. The PID is assigned to theport when it logs into the fabric (FLOGI).


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Deciphering FC AddressesMore FC Terms

Node and port names Fixed 64 bit addresses used touniquely identify Fabric devices also referred to as nodeand/or port world wide name (WWN)

Fabric Address Required address, needed for devicesand services to communicate, also referred to as

Port identifiers (PIDs)

24-bit addresses

Source ids (S_ID) or destination ids (D_ID)

Well-Known Addresses The Fabric addresses used foraccessing Fabric services

Fabric Services Intelligent services provided by aFabric, necessary for Fabric operation (more on these in

next module)


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FC Addresses - FC layersCompare to OSI layers:

Node / Port

WWNs

PID, 24 bit,

S_ID / D_ID


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Incorporated.


Node WWN Name Format

10:00:00:60:69:50:60:02

Single hexadecimalName Assignment

Authority (NAA) digit(Brocade uses a 1)

FC Standardreserved

Assigned by IEEE

Assigned by thevendor

Based on the IEEE Standard format, a typical SilkWorm Node WWN is:10:00:00:60:69:xx:xx:xx

Where: The first 2 bytes are always 10:00 (format 1 addressing); The next 3bytes are vendor specific. Brocade was assigned 00:60:69; The last 3 bytesare derived from the Brocade SilkWorm main board; The 3 byte company IDfound in the 64 bit IEEE Standard format WWN can be searched at:http://standards.ieee.org/regauth/oui/index.html

The 1st 4 bits of FC 64-bit addresses identify the authority responsible foradministration of that address or the Name Assignment Authority (NAA). Asubset of NAA address authority denotes the naming convention used. FC-PHRev 4.3 Fibre Channel standards table 41 define the NAA identifiers. Brocadeuses a HEX 1 in the first 4 bits this translates to a binary 0001 and tells youthat the Brocade node address represents an IEEE format 1 name which isbased directly on the 48-bit MAC address in the middle 3 bytes of 64-bitaddress (Brocades = 00:60:69). See the notes on the next slide for a list ofommon NAA identifiers.


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Incorporated.


Port WWN Name Format

20:00:00:60:69:50:60:02

Single hexadecimalName Assignment

Authority (NAA) digit(Brocade uses a 2)

Three hex digits usually setby the vendor to uniquelyidentify a port on a device

or switch

Assigned by IEEE

Assigned by thevendor

Fabric Port Name

2p:pp:00:60:69:xx:xx:xx

The next 3 nibbles (p:pp) are used by Brocade to show the switch portnumber.

20:04:00:60:69:1f:25:e6

The 0:04 which means this is port 4 on the switch

Common NAA identifiers include:

Format 5 IEEE registered addressing was added inFC-PH3 standards to extend the number of vendoraddresses beyond NAA = Ox1. Format 5 allowsvendors to uniquely use the whole address space (allbits) as a Vendor-Specific IDentifier (VSID).

01015

A format 2 address based on the same IEEE address

described in NAA HEX 1 identifier but used to defineports associated with a node using IEEE addressformat 1.

00102

Address based on IEEE 48-bit address (middle 3bytes of 8-byte (64-bit) address (WWN) - referred toas address format 1. Brocades = 00:60:69

00011

NAA descriptionBinaryHEX


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FC Device Node / Port WWNs

Switch Main Board Node WWN: 10:00:00:60:69:50:60:02

Switch Port 3 WWN:20:03:00:60:69:50:60:02

Each port on the switch will have a unique port WWN

A node WWN is often referred to as node name

A port WWN is often referred to asport name


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FC Device Node / Port WWNs Cont.

Switch Main Board Node WWN: 10:00:00:60:69:50:60:02

Switch Port 3 WWN:

20:03:00:60:69:50:60:02

HBA Node WWN:

10:00:12:34:56:00:10:0E

HBA Port 1 WWN:

11:00:12:34:56:00:10:0E

HBA Port 2 WWN:12:00:12:34:56:00:10:0E

HBA

Not all Fabric devices assign port WWNs the same. The fictitious HBA vendorpictured above used the 2nd nibble of the first byte to designate port numberswhile Brocade switch port WWNs use the 2nd nibble of the 2nd byte to designateports in WWN addressing.


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FC Addresses AnalogyTelephone Numbers for FC Devices

Telephone Service:

Telephone number to call

Your telephone number

Telephone service (accessed with your telephonenumber)

Fabric Service:

Destination ID (the Fabric address of whom youwant to communicate with)

Source ID (your Fabric address)

Fabric service


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FC Addresses

Fabric addresses are 24-bits (3 bytes long)

A devices Fabric address indicates:

The switch and port number to which thedevice is connected

The FC-type of device (Fabric or loop)

Fabric addresses are represented in hexadecimalformat (0x) which often appear before the address

Fabric addresses come in two modes: Native andCore PID address modes

Native Addressing Mode: The PID format on switches running Fabric OS v2.x andv3.x could originally only support a maximum of 16 ports in one switch. The 24-bit portaddress format consists of three bytes defining the Domain identifier, Area address andAL_PA fields respectively. Each field can provide 00-FF addressing. The Domain ID fieldbyte provides domain addressing 1-239. The three byte fields of the old PID formatwere defined as XX1YZZ, where Y was a hexadecimal number that specified a particularport on a switch and 1 was constant. When Brocade developed the ASIC for theSilkWorm 2000 series, the largest switch has 16 ports, so only half of the second bytein the Area field of the PID was required to specify ports.

Core PID Addressing Mode: To support the increased port count on the higher portcount products based upon Brocade Fabric OS v4.x, the new format XXYYZZ has beenadopted, where YY represents a port area designator. Using the entire middle byte forthe port area designator allows Brocade switches to scale up to the Fibre Channelstandard maximum of 256 ports per switch. Core PID addressing mode is the defaultaddress mode on all Brocade switches with greater than 16 ports.

To ensure inter-operability between Fabric OS v4.x based products and Fabric OS v2.xand v3.x based products, while maintaining compatibility with older firmware versions,a setting was created to enable the PID format to be set to use either the new format orthe old format. This is commonly known as the Core Switch PID format setting.


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FC Addresses Cont. Each switch (Domain) is responsible for assigning unique 24 bit

Fabric address (also referred to as PID, S_ID or D_ID)

Address are three bytes long:

Byte Zero: Domain Number 0x01 0xEF Byte One: Area Number* 0x0-0x255

Byte One: Native Mode/Port 0x0-0xF

Byte Two: Node Address 0x00 or > 0x00

00 or ALPA0-2551-239

00 or ALPA1-239

Node AddressArea NumberDomain Number

BYTE TwoBYTE OneBYTE Zero

0-F1

*Core PID Enabled on 16 port switches


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FC Addresses Cont.Address Assignment Dependency 3 Address Classifications:

Private Loop

Address

00 00 PP

Device LIPs PP =the local loop address(AL_PA)

Private address only usethe last byte (8 bits) ofthe 24-bit Fabric address

PP is always a non zerovalue

Fabric

Address

NN NN 00

NN NN 00 is the genericaddress of any Fabricdevice that has loggedinto the fabric (FLOGI).

Device FLOGI responseassigns 24 bit Fabricaddress

Native Mode has 2ndbyte1st nibble with a 1

Core PID mode usesentire 2ndbyteAREA

Public Loop

Address

LL LL PP

Where LL LL isassigned by the Fabric atlogin (FLOGI); and PP= the local loop address(AL_PA)

These devices 1st LIP toget 8 bit AL_PA andthen FLOGI and areassigned the other 16 bits(LLLL)

PP is always a non zerovalue

Fabric attached devices use an address format of NN NN 00, where NN NN00 is the address of any Fabric-attached device that has logged into thefabric. This Fabric assigned address 1 byte represents the domain of theswitch. the last byte (2 nibbles) is 00 indicating a Fabric device.

The 2nd byte or 3rd nibble is 1 (native mode) for a 2000 series, the 2nd byte 4th

nibble is the port, there are 15 possibilities (0-F).

Port counts greater than 15 required a change in addressing modes, so corepid addressing was developed and the 1 offset (2nd byte, 3rd nibble) was doneaway with. Core PID address mode uses an AREA designation to indicate portnumbers 0 256.

Public Loop attached devices use an address format of LL LL PP, where LLLL is assigned by the Fabric at login; and PP = the local loop address(AL_PA). This type of address is simply a Fabric assigned address for a deviceattached to an FL_Port (24 bits). The value of LL LL is the same for all PublicLoop devices attached to the same FL_Port and has the same meaning as NNNN Fabric addressing.

Private devices use an address format of 00 00 PP, where PP = the localloop address. A Private Loop device has a 1-byte, 8-bit address, called thearbitrated loop physical address (AL_PA). This type of address is all that aPrivate device is capable of receiving or sending (8 bits). Therefore, the Privatedevices may only communicate with the devices it can see on the local loop.


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Fabric Address Example 1Native Address Mode

Native address mode can be used when a 3900 or12000 is n o t present in the fabric: XX 1YZZ

XX is a value between 0x1 to 0xEF inclusiveThe 1 means Native Mode (think of it as a 1 offset)

Yis the port number (0-15)ZZ is the AL_PA for a loop device or 00 for an F_Port

A Brocade Fabric device will have low byte = 00

02 14 00

Port Number = 4

AL_PA = 00 (Non-Loop Fabric device)

A 1 can be used in theupper nibble of byte #2 if port count 16

Domain (Switch) ID = 2

Note: This is a Fabricdevice connected toswitch domain 2, port 4

A sample Fabric address:021500

XX1YZZ

XX=02 Domain_ID of the switch

1 Native mode

Y=5 Port #

ZZ=00 If 00, then it is an F_Port. If non-zero, then it is the AL_PAof the device on the FL_Port.


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Configuration required on OS v2.6.0+ and OS v3.02+ Enables attachment to higher port count switches that use OS v4.x

Configurable option under the configure command

Cor e Swi t ch PI D For mat : ( 0. . 1) [ 1] This format allows interoperability for switches with port > 16

Core PID address mode is default, non configurable address mode onswitches with greater than 16 ports

Set all configurable switches to CORE PID if possible

0a 21 00

Domain (Switch) ID = 0a = 10

AREA Number = 21

AREA = 21 HEX so this is port 33

AL_PA = 00 (Non-Loop Fabric device)

Fabric Address Example 2Core PID Address Mode

The PID format on switches running Fabric OS v2.x and v3.x could originally onlysupport a maximum of 16 ports in one switch. The 24-bit port address format consistsof three bytes defining the Domain identifier, Area address and AL_PA fieldsrespectively. Each field can provide 00-FF addressing. The Domain ID field byteprovides domain addressing 1-239. The three byte fields of the old PID format weredefined as XX1YZZ, where Y was a hexadecimal number that specified a particular porton a switch and 1 was constant. When Brocade developed the ASIC for the SilkWorm2000 series, the largest switch has 16 ports, so only half of the second byte in the Areafield of the PID was required to specify ports.

To support the increased port count on the higher port count products based uponBrocade Fabric OS v4.x, the new format XXYYZZ has been adopted, where YYrepresents a port area designator. Using the entire middle byte for the port areadesignator allows Brocade switches to scale up to the Fibre Channel standard maximumof 256 ports per switch.

To ensure inter-operability between Fabric OS v4.x based products and Fabric OS v2.xand v3.x based products, while maintaining compatibility with older firmware versions,a setting was created to enable the PID format to be set to use either the new format orthe old format. This is commonly known as the Core Switch PID format setting.


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A loop device will have a non-zero address in low byte.

This loop device is connected to switch 10 on port 16 andhas a loop address ofe8

To determine address mode on a switch with 16 or lessports, check the core PID address mode using configshowor configure commands

0a 10 e8

Domain (Switch) ID = 0a = 10

Area Number = 10

AREA = 10 HEX so this is port 16

Loop Address = e8 (loop device)

Fabric Address Example 3Core PID, Public Loop Address Mode


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Well-Known Addresses of Fabric Services

WellWell--Known AddressesKnown Addresses

Brocade Fabric Operating System

Broadcast

Server

FFFFFF

Alias

Server

FFFFF8

Mgmt

Server

FFFFFA

Time

Server

FFFFFB

Fabric

Controller

FFFFFD

Directory

Server

FFFFFC

Fabric

Login

FFFFFE

Every switch has reserved three byte addresses known as Well Known Addresses. Theservices residing at these addresses provide a service to either nodes or managementapplications in the fabric.

Fabric Login: Before a fabric node can communicate with services on the switch orother nodes in the fabric an address is assigned by the fabric login server. Fabric

addresses assigned to nodes are three bytes long and are a combination of the domainid plus the port area number of the port the node is attached to.

Directory Server: The directory server/name server is where fabric/public nodesregister themselves and query to discover other devices in the fabric.

Fabric Controller: The fabric controller provides state change notifications toregistered nodes when a change in the fabric topology occurs.

Time Server: The time server sends to the member switches in the fabric the time oneither the principal switch or the Primary FCS switch.

Management Server: The Management server provides a single point for managingthe fabric.

Alias Server: The Alias server keeps a group of nodes registered as one name tohandle for multicast groups

Broadcast Server: This service is optional and when frames are transmitted to thisaddress are broadcasted to all operational N and NL ports.

When registration and query frames are sent to a Well Known Address a differentprotocol service, Fibre Channel Common Transport (FC-CT), is used. This protocolprovides a simple, consistent format and behavior when a service provider is accessedfor registration and query purposes.


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Fibre Channel Terminology Cont.Review

Fibre Channel uses Exchanges to send Sequences of Frames

The Exchange manages the transaction it contains a set of relatedsequences

Sequenceswithin the Exchange hold sets of related Fibre Channel frames

AFrame contains a header and payload and is up to 2148 bytes

An example Small Computer Serial Interface (SCSI) Read Command:

Initiator Target

CMD (Sequence)

DATAIN (Sequenc

e)

STATUS(Sequence)

Sequences of Frames

OneExchange

An exchange can be bi-directional

Sequences and frames are uni-directional


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Buffer Buffer

Sequence 1

Sequence 2

Sequence 3

N_Port A

SO

F

Header

CR

C

EO

FData

Sequence

Exchange

(Transactions)

Frames, sequences, and exchanges can all be multiplexed

(server/storage/Work Station (WS))

FC Frame(Max. payload 2112 Bytes)

Information Units

(Large Blocks)

(server/storage/WS)N_Port B

Fibre Channel Terminology Cont.Fibre Channel Information Transfer

This picture shows the flow of data in the Fibre Channel environment for apoint-to-point connection or a Fibre Channel connection through a Fabric. Oneor more frames will be sent and those frames can reside in one or moresequences. The sequences reside in an Exchange. From the other point of view:Exchanges consist of sequences of frames. The flow control (throttling of datafrom one port to another) depends upon the class of service (COS) being usedas specified during PLOGI when common service parameters where exchanged.

Exchange Composed of 1-n non-concurrent sequences

Unit- or bi-directional flow of sequences for an operation

Exchanges normally uses the same ULP

Exchange may be Identified by each end: Originator / Responder Exchange IDs(OX_ID, RX_ID), RX_ID is frequently optional

Exchange controls found in F_Ctl frame header field are: Seq_Init (initiatingsequence); First_Seq (indicates first sequence of exchange); Last_Seq (indicateslast sequence of exchange); Seq_ID (sequence identifier) Info_CAT- UnsolicitedCommand (information category); Exc_Contxt (indicates whether originator orresponder in Exchange)

Sequence

Composed of 1-n Frames

Unidirectional set of frames for an operation

Each Sequence is identified by initiator: Sequence Identifier (SEQ_ID)

Each frame within a Sequence is numbered: Sequential Count (SEQ_CNT)

Other sequence controls: SOFiX (start of frame for class x used to indicate class ofservice this sequence is using, SOFnX is used for subsequent frames); R_CTL(routing control to indicate data, ACK (for COS 1,2,4,6 and F); End_Seq (set to 1 forlast sequence); SEQ_CNT (SEQ_CNT is incremented by 1 for each data frame sent);EOF (last frame of sequence will be indicated by a EOFt)

Frame:

Frame is smallest unit of transfer and is discussed in more detail in the next slide.


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Fibre Channel Terminology Cont.FC-PH Generic Frame - Frame Header

FC header contains vital frame information:

Control information (routing, class, sequence count)

Addressing (Source and Destination)

Important bytes:

R_CTL = Routing Control

Destination Fabric Address

Source Fabric Address

Protocol Type:SCSI, IP

Payload word that defines

what is being said called

command code

Payloads often contain node

and port names

Byte 0 Byte 1 Byte 2 Byte 3

R_CTL Destination ID (D_ID)

CS_CTL Source ID (S_ID)

Type Frame CTL

SEQ_ID DF_CTL SEQ_CNT

OX_ID RX_ID

Parameter

Word 0

Word 1

Word 2

Word 3

Word 4

Word 5

Word 6

Payload

R_CTL - Routing Control bits communicate the type of frame we are looking at:Extended Link Service Frame, Data Frame, and Acknowledge Frames are common.D_ID - Destination ID (Native port address or well-known address)CS_CTL - Class specific Control Field. This field is always zero for Classes 2 and 3 perthe standards but may change in the futureS_ID - Source ID (Native port address or well-known address)Type - Data Structure Type that describes what the data is:

i.e., 01 = Extended Link Services05 = ISO/IEC 8802-2 LLC/SNAP (IPFC)08 = SCSI FCP20 = Fibre Channel Services

F_CTL - Frame Control. This field contains information related to the frame contents.Example: First/last sequence, passing initiativeSEQ_ID - Sequence IDDF_CTL - Data Field Control. This field indicates if there are any optional headersSEQ_CNT - sequence Count - Indicates the sequential order of the frame in thesequenceOX_ID - Originator ID - Exchange ID assigned by the originatorRX_ID - Responder ID - The exchange ID assigned by the responder to the ExchangeData Field/Payload - This is the payload of the frame and can be from 0 to 2112bytes in length

The R_CTL byte is one of the first items to check.

Note: S_ID and D_Ids are also referred to as PIDs (port identifies) or 24 bit addresses.


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FC Topologies include Point-to-Point, Arbitrated Loop and SwitchedFabric

FC Terminology discussed includes Fabric, Nodes, Ports, and a review ofExchanges, Sequences and Frames

FC devices have node and port WWNs

FC device address classifications: Private, Fabric and Public Loop

FC addresses are called Port Identifiers (PIDs), 24-bit addresses, andS_ID, or D_ID addresses

Well-known Addresses are used to communicate with Fabric services

The FC Frame is 2148 Bytes and includes a SOF, Header, Payload, CRCand EOF

The header contains D_ID, S_ID, OX_ID and RX_ID identifiers

Summary


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Use resources pageInternet Link section - Find SAN ED

101 linkSAN Fabric Foundation, look at chapter 2 (FibreChannel Essentials) for additional information aboutmaterial presented in this module

Use resources pageReference section - FC_ALInitialization presentation for detailed FC_AL initializationinformation

Additional Information

FCToposAddrs

Documents

Transcript of FCToposAddrs