Shortest Path Bridging IEEE 802.1aq Tutorial and Demo

FDB visually: uca

:2

9

:1

10

:6

MAC | BVID | IF
:4 | 1 | 9
:4 | 2 | 9
:4 | 3 | 10
:4 | 4 | 10

ast m-in-m mode

:3

3

6 :4

:5

MAC | BVID | IF
:1 | 1 | 3
:1 | 2 | 6
:1 | 3 | 3
:1 | 4 | 6

26

FDB (mcast M

If no services require tan
there is no tandem FDB:

Very VPLS like .. Pre
replication over uni

Else (mp2mp like but wit
If my node is on a un
between node A , w
group I, and node B
I, then:
merge into the FD
{ A/Group I } to th

M-in-M mode)

ndem replication
:
etty boring….head
icast paths .. Yawn..

thout signaling)
nique shortest path
which transmits for a
B which receives on group

DB an entry for traffic from
he interface towards B.

27

How does it work
format (n/a for h

Example: { SOURCE: 0A-
MMAC-DA: A3

001

– transit multicast
head replication)

-BC-DE / ISID: fe-dc-ba } 28

3-BC-DE-FE-DC-BA

11

FDB visually: mca

I=255 9 :2

:1 6
10
:6 5

MMAC |BVID|IF MM
{:1/255}|4 |10 {:

ast m-in-m mode

I=255

:3
:4 I=255

:5

MAC |BVID| IF
:1/255}|4 |5,6

29

Animation for 8 me

ember E-LAN ‘255’

I-SID 255 has 8
members

Shown are all
routes used by
this I-SID in pink.

Two trees shown
blue/green.

Note symmetry
of trees between
source/dest

If transit multicast
selected fork
points in trees are
replication points.

30

The Control Plane

•  Industry standard IS-IS L
basis for 802.1aq.

•  Does not require any IP
•  Does not preclude IPV4

same IS-IS instance.
•  SYSID carries B-MAC ad
•  Introduces no new PDU’
•  Hello TLVs augmented t

Algorithm / Vid informatio
•  Update TLV’s augmente

specific link costs.
•  Update TLVs augmented

information.
•  Update TLVs augmented

form’ name SPSOURCE

e (m-in-m mode)

Link State Protocol is

to operate.
or IPV6 being present in

ddress
’s to IS-IS.
to pass Equal Cost
on and new NLPID.
ed to advertise SPB

d to advertise ISID

d to advertise nodal ‘short
EID (transit mcast only).

31

802.1aq ISIS LSP ex

LSPID Seq Num

--------------------------------

4455.6677.0001.00-00 0x0000007

SOURCE 4455.6677.0001.00

HOST NAME Instance_1
NLPID
SPB (0xC1) (2)
AREA ADDR 22.3344

NBR ID 4455.6677.0004.00

NBR ID 4455.6677.0003.00

SPSOURCEID 07-00-01

SPB ECT-ALGORITHM 1 ECT-VID

SPB ECT-ALGORITHM 0 ECT-VID

SPB BMAC 44-55-66-77-00-01

ECT-VID 100

SPB ISID 255T&

SPB BMAC 44-55-66-77-00-01

ECT-VID 101

SPB ISID 256T&

xtensions at a glance

Checksum ….
---------------

7a 0xc01f ….. :4
:3
(1)

255 10
256
(3) :1 10

COST: 10
COST: 10

101 (4)
100

1 LSP fragment for
node :1 with 2 peers
&R (5) :4 and :3 and two
services 255, 256
1
32
&R

TIE BREAK

Symmetric Tie Breaking Requires that:
•  Forward and Reverse path are th
•  Every subset of the end to end sh
path under the same tie breaking
SPF(A,C) = SPF(A,B) || SPF(B,

Solution – assign to a path a ‘Path Iden
•  Path Identifier := Sorted List of N
•  Given a choice between two path
Path Identifier.

KING/ECT

he same
hortest path must also be a shortest
g rules (transitivity): I.e.
,C) <- required for hop by hop fwding
ntifier’
Nodes between SRC/DST
hs. Pick path with smallest

33

TIE BREAKING

:2 :3
:1 :4

:6 :5

A path is symmetrically/deterministically

Lowest path identifier (i.e. path with low
proof left as exercise for the interested

ECT – CONT’D

PATH IDs

:2 :3 smallest
:5 :6
:3 :6
:2 :5

y chosen by picking the path with the 34

west Bridge Identifier on it). Transitivity
reader.

TIE BREAKING

:2 :3
:1 :4

:6 :5

Applying a known bit mask to Bridge ID’

will cause different selection. Inversion (
Path ID.

ECT – CONT’D

PATH IDs

:3 :2 smallest
:6 :5
:6 :3
:5 :2

’s and running the same algorithm
(shown) is equivalent to picking largest

35

TIE BREAKING

•  In total 16 bit masks. 0x00..0x11,0x

•  This yields 16 possible shortest pat

•  Paths can be tuned since Bridge Pr
as high 2 bytes. Bridge Identifier = B

•  Adjusting Bridge Priority up or down

•  Picking 16 priorities and assigning d
spread through cut. Eg: spine of a D

•  The 802.1aq TLV’s support Opaque
on ECT.

•  The Opaque ECT behaviors are de
as next step.

ECT – CONT’D

x22 … 0xee,0xff are provided.
ths.
riority is included in Bridge Identifier
Bridge Priority:16 || SYSID
n allows tuning of ECT.
down network ‘cut’ yields perfect
DC fabric.
e ECT behavior to allow further work

esigned to allow ECMP (hash based)

36

TIE BREAKING

Can get perfect balance
down spine of a two layer
16 ECT L2 Fabric. Shown
Are all 16 SPF’s from 2<->24

ECT – CONT’D

16 different SPF trees

Each use different spine
as replication point.

Shown is one of the 16
SPF’s from/to node 1.

37

Loop Suppressio

Suppression
•  done on the data path usi
•  prevents 99.99% loops if
•  no impact on convergence
•  exploits symmetric/congru
•  uses reverse learning opt

Forward(pkt, inIf) {

if (l2table[pkt.sa,pkt.vid].outIf != in

discard (pkt); :

else …
}

On :6
/7 != /5 so discard

on & Avoidance

ing an SA check.
FDB’s create one.
e rates.
uence properties of routing.
tions of most h/w to discard.

SD D :3 :D
DS :5
:2 38
S
nIf)

:S
/7
:6 /8
D
L2table
D-> if/8
S-> if/5

Loop Suppressio

Avoidance
•  hellos augmented with top
•  mismatched topology => s
•  blocks ‘unsafe’ entries.
•  Unsafe => distance chang
outside “safe z

loop risk Bound on safe

on & Avoidance

pology ‘digests’
some forwarding entries unsafe.

ged Fold in path=loop
zone”

e movement loop risk

39

802.1aq OA&M (in

Service/Network Layer – 802
• Hierarchy (honors mainte
• Continuity Check
• L2 traceroute
• L2 ping

Link Layer – 802.3ah
• Link Monitoring (logical/ph
• Remote Failure Indication
• Remote Loopback

Service Layer - Y.1731
• Multicast Loopback – dep
• Performance Measureme
• One way/two way delays

nherited by design)

2.1ag Connectivity Fault mgmt
enance levels/abstraction)

hysical)
n

pends on congruency/symmetry

ents (Loss/Delay etc.)

– symmetry important 40

802.1aq OAM

1.  Continuity Check (CC)

a)  Multicast/unidirectional
heartbeat

b)  Usage: Fault detection

2.  Loopback – Connectivity Check

a)  Unicast bi-directional
request/response

b)  Usage: Fault verification

3.  Traceroute (i.e., Link trace)

a)  Trace nodes in path to a
specified target node

b)  Usage: Fault Isolation

4.  Discovery (not specifically supported by .1a

support it)
a)  Service (e.g. discover all nodes supportin
b)  Network (e.g. discover all devices comm

5.  Performance Monitoring (MEF10 and 12 -

and mpt-mpt)

a)  Frame Delay, Frame Loss, Frame Delay
b)  Usage: Capacity planning, SLA reporting

M capabilities

ag however Y.1731 and 802.1ab

ng common service instance)
mon to a domain)

Y.1731 for pt-pt now extending to pt-mpt

y Variation (derived)
g

41

MIBs (also all OA

SpbSys Basic config
SpbSysDynamic Basic run tim
SpbEctStatic Desired Equ
SpbEctDynamic Actual Equa
SpbAdjStatic Desired Adj
SpbAdjDynamic Actual Adjac
SpbTopNode All other no
SpbTopEct All other EC
SpbTopEdge All other Ed
SpbTopSrv All services

A&M etc. inherited)

g data
me data
ual cost behaviors
al cost behaviors
jacency data (metric etc.)
cencies
odes in the SPB region and basic data
CT behavior in the SPB region
dge data in the SPB region
in the SPB region, who hosts etc.

42

Rapid R

•  ISIS augmented with multica
nodes.

•  Every 802.1aq node joins de
•  This E-LAN is just for contro
•  LSPs can be advertised ove
•  Very fast distribution protoco
•  On failure each end of link a

this ‘default’ E-LAN (in addit
•  Reaches all 802.1aq particip

with no CPU involvement tra
•  Conceptually like having a s

with a physical port but no D
used as unreliable very fast
backed up by normal IS-IS h

Recovery

ast LSP flood to all 802.1aq

efault service ISID 0xffffff.
ol plane.
er this E-LAN
ol (h/w multicast).
advertises over
tion to normal updates).
pants at h/w multicast speed
ansit.
shared LAN joining all nodes
DR election etc. is done, only

distribution mechanism
hop by hop LSPs.

43

TLV Su

+-----+----+-----------------+

| PDU |TLV | SUB-TLV |

+-----+----+-----------------+

IIH

MT-Port-Capability

SPB-B-VID

SPB-Digest

LSP

MT-Capability

SPB-Inst

SPB-I-OALG

SPBM-SI

SPBV-ADDR

MT-Intermediate-System

SPB-Metric

SPB-A-OALG

No new PDU, no changes

ummary

+--------+------+-------------+
| TYPE | TYPE | #OCCURRENCE |
+--------+------+-------------+

143
51
61

144
11
2 >=0
3 >=0
4 >=0

222
12 1
13 >=0

to IS-IS state machine logic

44

TLV – SPB-Di

All TLV’s in context of an MTID TL

+-+-+-+-+-+-+-+-+

|Type=SPB-Digest| = 6

+-+-+-+-+-+-+-+-+

| Length | (1 byte)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

| MCID (

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

| Aux MCID (

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

| Agreement Digest (

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

|RES | A | D|

+-+-+-+-+-+-+-+-+

ALSO in Hello the NLPID value 0xC1

HELLO padding unchanged ..

igest (in Hello)

LV

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

(50 Bytes) |

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

(50 Bytes) |

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

(32 Bytes) |

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

1 is used and advertised.

45

TLV – SPB-B-

+-+-+-+-+-+-+-+-+

|Type= SPB-B-VID| = 5

+-+-+-+-+-+-+-+-+

| Length | (1 byte)

+-+-+-+-+-+-+-+-+----------------

| ECT - VID Tuple (1) (6 by

+--------------------------------

| .........................

+--------------------------------

| ECT - VID Tuples (N) (6 b

+--------------------------------

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECT - Algor
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Base VID (12 bits) |U|M|RES|

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

-VID (in Hello)

----------------+

ytes) |

----------------+

|

----------------+

bytes) |

----------------+

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

rithm (32 bits) |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

|

+

46

TLV – SPB

+-+-+-+-+-+-+-+-+

|Type = SPB-Inst| = 1

+-+-+-+-+-+-+-+-+

| Length | (1 byte)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

| CIST Root Identifi

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

| CIST Root Identifi

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

| CIST External ROOT Pat

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

| Bridge Priority |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

|R R R R R R R R R R R|V|

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

| Num of Trees | (1 bytes)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

| VLAN-ID (1) Tup

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

| VLAN-ID (N) Tup

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

B-Instance

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

ier (4 bytes) |

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

ier (cont) (4 bytes) |

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

th Cost (4 bytes) |

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

(2 bytes)

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

SPSOURCEID |

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

ples (8 bytes) |

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

ples (8 bytes) |

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

47

TLV – SP

+-+-+-+-+-+-+-+-+

|Type=SPB-Metric| = 12

+-+-+-+-+-+-+-+-+

| Length | (1 byte)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| SPB-LINK-METRIC

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Num of ports | (1 byte)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Port Identifier | ( 2 bytes

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Future Expanded ECMP behaviors …

+-+-+-+-+-+-+-+-+

|Type=SPB-A-OALG| = 13

+-+-+-+-+-+-+-+-+

| Length | (1 byte)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Opaque ECT Algorithm (4

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Opaque ECT Information (va

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

PB-Metric

+-+-+
| (3 bytes)

+-+-+
s)

+-+-+-+-+-+-+-+-+-+-+

4 bytes) |

+-+-+-+-+-+-+-+-+-+-+

ariable) |

+-+-+-+-+-+-+-+-+-+-+

48

TLV – SPB-Se

+-+-+-+-+-+-+-+-+

|Type = SPBM-SI | = 3

+-+-+-+-+-+-+-+-+

| Length | (1 byte)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| B-MAC ADD

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| B-MAC ADDRESS (6 bytes) |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

|T|R| Reserved |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

|T|R| Reserved |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

|T|R| Reserved |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

ervice Instance

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

DRESS |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Res. | Base-VID (12 bits) |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

ISID #1 |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

ISID #2 |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

ISID #n |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

49

Out

•  Challenges
•  What is 802.1aq/SPB
•  Applications
•  How does it work
•  Short Demo (remote

tline

B
e switch if possible)

50