Transcript
Shortest Path Bridging
IEEE 8021aq
Overview
APRICOT/Hong Kong/Feb 24th 2011
Peter Ashwood-Smith
peterashwoodsmith@huaweicom
Fellow
Shortest Path Bridging
IEEE 8021aq
Overview
APRICOT/Hong Kong/Feb 24th 2011
Peter Ashwood-Smith
peterashwoodsmith@huaweicom
Fellow
Abstract Abstract
8021aq Shortest Path Bridging is being standardized by the IEEE as an
evolution of the various spanning tree protocols 8021aq allows for true
shortest path routing, multiple equal cost paths, much larger layer 2
topologies, faster convergence, vastly improved use of the mesh topology,
single point provisioning for logical membership (E-LINE/E-LAN/E-TREE
etc), abstraction of attached device MAC addresses from the transit
devices, head end and/or transit multicast replication , all while supporting
the full suit of 8021 OA&M
Applications consist of STP replacement, Data Center L2 fabric control,
L2 Internet Distributed Exchange point fabric control, small to medium
sized Metro Ethernet control planes L2 wireless network backhaul…
Outline Outline
Challenges
What is 8021aq/SPB
Applications
How does it work
Status
Challenges Challenges
L2 networks that scale to ~1000 bridges
Use of arbitrary mesh topologies
Use of (multiple) shortest paths
Efficient broadcast/multicast routing and replication points
Avoid address learning by tandem devices
Get recovery times into 100’s of millisecond range for largertopologies
Good scaling without loops
Allow creation of very many logical L2 topologies (subnets)
of arbitrary span
Maintain all L2 properties within the logical L2 topologies(transparency, ordering, symmetry, congruence, shortestpath etc)
Reuse all existing Ethernet OA&M 8021ag/Y1731
“Make a network of switches look like a single switch!”
5
Example problems of scaling up
Native Ethernet
ROOT
1- Can’t use
these links
Source
Dest
A1 A100
3 Must learn A1A100
2- poor
routes
Outline Outline
Challenges
What is 8021aq/SPB
Applications
How does it work
Status
What is 8021aq/SPB What is 8021aq/SPB
IEEE protocol builds on 8021 standards
A new control plane for Q-in-Q and M-in-M
Leverage existing inexpensive ASICs
Q-in-Q mode called SPBV
M-in-M mode called SPBM
Backward compatible to 8021
8021ag, Y1731, Data Center Bridging suite
Multiple loop free shortest paths routing
Excellent use of mesh connectivity
Currently 16, path to 1000’s including hashed per
hop
Optimum multicast
head end or tandem replication
What is 8021aq/SPB (cont’d) What is 8021aq/SPB (cont’d)
Light weight form of traffic engineering
Head end assignment of traffic to 16 shortest paths
Deterministic routing - offline tools predict exact routes
Scales to ~1000 or so devices
Uses IS-IS already proven well beyond 1000
Huge improvement over the STP scales
Good convergence with minimal fuss
sub second (modern processor, well designed)
below 100ms (use of hardware multicast for updates)
Includes multicast flow when replication point dies
Pre-standard seeing 300ms recovery @ ~50 nodes
IS-IS
Operate as independent IS-IS instance, or within IS-IS/
IP, supports Multi Topology to allow multiple instancesefficiently
What is 8021aq/SPB (cont’d) What is 8021aq/SPB (cont’d)
Membership advertised in same protocol astopology
Minimizes complexity, near plug-and-play
Support E-LINE/E-LAN/E-TREE
All just variations on membership attributes
Address learning restricted to edge (M-in-M)
FDB is computed and populated just like a router
Unicast and Multicast handled at same time
Nodal or Card/Port addressing for dual homing
Computations guarantee ucast/mcast…
Symmetry (same in both directions)
Congruence (unicast/multicast follow same route)
Tune-ability (currently 16 equal costs paths opaqueallows more)
Multiple Shortest Path routing&Ethernet OA&M
All links usable
End result - Visually
Multiple Shortest Path routing&Ethernet OA&M
All links usable
End result - Visually
Outline Outline
Challenges
What is 8021aq/SPB
Applications
How does it work
Status
Applications Applications
Anywhere that Spanning Tree is being used
Take existing STP/MSTP based network and migrate to
Shortest Path Routing
Ethernet Exchange Points
Big distributed switch to interconnect hundreds of different
customers cheaply with L2VPNs
Metro Ethernet
Light weight metro protocol, L2VPN solution simpler than VPLS
with lower capex/opex
Wireless backhaul
Use of L2VPN for LTE backhaul
BIG L2
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Application Data Center
Multiple shortest path routing
inter server traffic
Deterministic traffic flows
Flexible subnet expand/shrink anywhere
Virtualization operates in subnet
Fully compatible with all 8021
Data Center Bridging protocols & OA&M
Address isolation through m-in-m
Fast recovery
No loops
111*
112*
Application Data Center (cont’d)
Totally compatible with Vmware server functions:
OA&M, motion, backup etc
Apps that sit on Vmware ‘just work’
Fully compatible with all load balancer ADC appliances
VRRP transparent (primary/stdby rtr per subnet)
or proprietary variations on same protocol
Compatible with emerging Inter DC overlay work or
Inter DC L2 tunnels
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A15 A16
B29 B30 B31 B32
A1 A2
B1 B2 B3 B4
48 switch non blocking 2 layer L2 fabric
16 at “upper” layer A1A16
32 at “lower” layer B1 B32
16 uplinks per Bn, & 160 UNI links per Bn
32 downlinks per An
Non Blocking Switching Cluster
(16 x 100GE per Bn )x32 = 512x100GE = 512T
160 x 10GE server links (UNI) per Bn
(32 x 160)/2 = 2560 servers @ 2x10GE per
S1,1 S1,160 S3,1 S3,160 S32,1 S32,160
5120 x 10GE
16 x 100GE
160 x 10GE
32 x 100GE
Good
numbers
“16”
& “2”
levels 16 x 32 x 100GE = 512T
using 48 x 2T switches
So 102T
100+ Terra non blocking interconnection
fabric (if switches non blocking)
Outline Outline
Challenges
What is 8021aq/SPB
Applications
How does it work
Status
How does it work? How does it work?
From Operators Perspective
#NAME?
-Group ports/c-vlan/s-vlan at UNIs that you
want to bridge (224 groups=‘services’ m-in-m
mode)
#NAME?
-Use your 1ag OA&M
Internally
#NAME?
-IS-IS advertises box MACs (so no config)
#NAME?
#NAME?
members
Data Path (M-in-M mode) Data Path (M-in-M mode)
C-vlan/S-vlan or untagged traffic arrives at UNI
Its encapsulated with B-SA of bridge
Its encapsulated with I-SID configured for group
Its encapsulated with B-VID chosen for route
C-DA is looked up, if found B-DA is set
C-DA not found, B-DA is multicast that says:
Multicast to all other members of this I-SID
group from ‘me’ Or can head-end replicate
over unicast
C addresses to B address association
learned at UNI only
FDB (unicast M-in-M mode) FDB (unicast M-in-M mode)
A unique shortest path from node to all others
is computed
BMAC of other nodes installed in FIB pointing
to appropriate out interface
Above is repeated for 16+ shortest paths each
causes a different B-VID to be used
Symmetry is assured through special tie-
breaking logic 16+ different tie-breaking
algorithms permit 16+ different shortest paths
FDB visually: ucast m-in-m mode FDB visually: ucast m-in-m mode
FDB (mcast M-in-M mode) FDB (mcast M-in-M mode)
If no services require tandem replication
there is no tandem FDB:
Very VPLS like Pretty boring…head replication over
unicast paths
Else (mp2mp)
If my node is on a unique shortest path between node A ,
(which transmits for a group I) and node B
(which receives on the same group I), then:
merge into the FDB an entry for traffic from
DA ={ A/Group I} to the interface towards B
I=255
I=255
I=255
MMAC |BVID| IF
{:1/255}|4 |5,6
8021aq OAM capabilities
1
8021aq OAM capabilities
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 (ie, Link trace)
a)
Trace nodes in path to a
specified target node
b)
Usage: Fault Isolation
4
Discovery (not specifically supported by 1ag however Y1731 and 8021ab
support it)
a) Service (eg discover all nodes supporting common service instance)
b) Network (eg discover all devices common to a domain)
5
Performance Monitoring (MEF10 and 12 - Y1731 for pt-pt now extending to pt-mpt
and mpt-mpt)
a) Frame Delay, Frame Loss, Frame Delay Variation (derived)
b) Usage: Capacity planning, SLA reporting
Outline Outline
Challenges
What is 8021aq/SPB
Applications
How does it work
Status
Status Status
DEPLOYMENTS:
Pre-standard SPBM live customer networks:
3 carrier (20+nodes)
5 enterprise
3 dc deployments
SPBM Data path (PBB) and OA&M of course has large number
of deployments world wide
INTERWORKING:
Avaya (ERS 8800) + Huawei (S9300) successful Inter-working
including full line rate data paths + L2 ping x 5 physical 32
logical nodes
IETF:
In IESG last call, RFC imminent ~1Q 11
IEEE:
Expected completion ~3Q 11
References References
“IEEE 8021aq” : wwwwikipediaorg:
http://enwikipediaorg/wiki/IEEE_8021aq
Good overview, up to date with lots of references / tutorial videos all linked
http://wwwietforg/internet-drafts/draft-ietf-isis-ieee-aq-04txt
The IETF IS-IS draft soon to be RFC
“Shortest Path Bridging Efficient Control of Larger Ethernet Networks” :
IEEE Communications Magazine Oct 2010
“Provider Link State Bridging” : IEEE Communications Magazine V46/N9 Sept 2008
Thank-You