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Vakgroep Informatietechnologie – Onderzoeksgroep IBCN
Label scalability of Carrier Ethernet
Benchmarking Carrier Ethernet Technologies Workshop Session AI.2 - Scientific and Technical ResultsEuroNGI 2008, Krakow, Poland April 30, 2008
Wouter Tavernier, Koen Casier (Ghent University – IBBT)Luis Caro (University of Girona)Dimitri Papadimitriou (Alcatel-Lucent Bell NV)
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Agenda
PROBLEM STATEMENT
Labels in Carrier Ethernet Label scalability Label optimization
Results
Short word on label lookups
Conclusion
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Problem statement
Evolution of Ethernet being a LAN technology towards a Carrier Technology Ethernet = low cost Ethernet = ubiquitous Ethernet = plug & play
LAN environments: traffic streams between tens of end-users Metro/Access environments: traffic streams between thousands of end-users
PROBLEM STATEMENT: Is Carrier Ethernet able to cope with increasing number of traffic streams
IP/ MPLS
ISP1
ISPn
Video
WWW
LargeCO
Level 2remotes
RegionalPOP
RU/MTU
Small CO /Level 1remotes
AggregationNetwork
[ring / star]
< 5,5 km< 1,5km 2,1 - 3,0 km
ADSL/ADSL2+
VDSL
FE/GigEor PON
ADSL
RAM /DLC
FE/GigE/SONET
CLE
BRAS
CustomerPremises
RegionalNetwork
BroadbandServices
Aggregator
AccessNetwork
[ring / star]
BNG
EthernetAggregation
(optional)
< 50 km
@ 50% penetration@ 10% penetration
# of lines
# of customers 50-50010-100
100-1K
100-2K20-400
200-4K
5K-10K
1K-2K
10K-20K
25K-50K
5K-10K
50K-100K
SDSL (business) FE/GigE/SONET/CDWM
OLT /CO DSLAM
Metro Core Core
Metro Aggregation
Metro Access
First Mile
Ethernet
Around 5 to 10 nodes
IP/ MPLS
ISP1
ISPn
Video
WWW
LargeCO
Level 2remotes
RegionalPOP
RU/MTU
Small CO /Level 1remotes
AggregationNetwork
[ring / star]
< 5,5 km< 1,5km 2,1 - 3,0 km
ADSL/ADSL2+
VDSL
FE/GigEor PON
ADSL
RAM /DLC
FE/GigE/SONET
CLE
BRAS
CustomerPremises
RegionalNetwork
BroadbandServices
Aggregator
AccessNetwork
[ring / star]
BNG
EthernetAggregation
(optional)
< 50 km
@ 50% penetration@ 10% penetration
# of lines
# of customers 50-50010-100
100-1K
100-2K20-400
200-4K
5K-10K
1K-2K
10K-20K
25K-50K
5K-10K
50K-100K
SDSL (business) FE/GigE/SONET/CDWM
OLT /CO DSLAM
Metro Core Core
Metro Aggregation
Metro Access
First Mile
Ethernet
Around 5 to 10 nodes
LAN Metro networkL
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
No labels in bridged Ethernet
A
B
C
X
Y
Z
ZC
12
3
512
3
4
Dest Out Port
X 1
Z 3
A 4
Dest Out Port
B 2
X 5
Z 5
C 3
Forwarding in native Ethernet bridging : stateless (CL) 48 bit MAC-address based
SA PayloadDA
7 6 6
Sync SD
1 46 - 1500
EthType
2
ZC
ZC
ZC
ZC
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Labels in Carrier Ethernet
A
B C
D
E
The concept of a connection (LSP) allows for (CO): Traffic Engineering Advanced recovery/protection techniques BW guarantees
Forwarding is based on a label linked to the connection state
Two connections (LSPs) from A to ETwo connections (LSPs) from A to E: maintains state for the green and red connection and forwards based on a
label
Labell
Labell
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Domain-wide PBB-TE label
A
B C
D
E
<100, E>
<200, E>
<100, A>
Distinct routes for dest E, by diff B-VID.
Ingress A has 2 LSPs to E, for e.g.: Protection switching Load balancing
B-VID 100 reused on same link
C-DA C-SA C-TAG
C-DA C-SA S-TAG Type DATA
Type DATA
C-TAG
B-DA B-SA B-TAG 802.1ad FramePrio I-SID
FCS
FCS
FCS
6 octets 6 octets 4 octets 2 octets 2 octets
6 octets 6 octets 4 octets 4 octets 2 octets 2 octets
6 octets 6 octets 4 octets 1 octet 3 octets 2 octets
Customer Frame
802.1ad S-tagged Frame
802.1ah I-tagged Frame
Label remains constant along connection (no SWAP)!
Label remains constant along connection (no SWAP)!
E,2
00
E,200
E,200
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
C-DA C-SA C-TAG
C-DA C-SA S-TAG Type DATA
Type DATA
C-TAG
B-DA B-SA B-TAG 802.1ad FramePrio I-SID
FCS
FCS
FCS
6 octets 6 octets 4 octets 2 octets 2 octets
6 octets 6 octets 4 octets 4 octets 2 octets 2 octets
6 octets 6 octets 4 octets 1 octet 3 octets 2 octets
Customer Frame
802.1ad S-tagged Frame
802.1ah I-tagged Frame
Link local ELS label
A
B C
D
E
Distinct routes for dest E, by diff S-VID.
Ingress A has 2 LSPs to E, for e.g.: Protection switching Load balancing
Label remains constant along connection (no SWAP)!
100
Label can be swapped in intermediate hops along connection!
200
B-VID 100 reused on same link
100
S-VID 100 reused on other link
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Label usage optimization
Label balancing (online routing optimized ELS) Shortest path routing takes into account labels used on a link as
cost Merging (ELS)
1 incoming label per interface + 1 outgoing label GAIN: x-1 labels on outgoing local interface
Shared forwarding (PBB-TE) 1 label needed GAIN: x-1 global labels
.
.
.x incoming
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Label scalability
Given the label:
How do different label schemes react under changing conditions?
What is the influence of the topology? What is the influence the traffic matrix? What is the influence of the traffic matrix on typical BW
usage?
C-DA C-SA C-TAG
C-DA C-SA S-TAG Type DATA
Type DATA
C-TAG
B-DA B-SA B-TAG 802.1ad FramePrio I-SID
FCS
FCS
FCS
6 octets 6 octets 4 octets 2 octets 2 octets
6 octets 6 octets 4 octets 4 octets 2 octets 2 octets
6 octets 6 octets 4 octets 1 octet 3 octets 2 octets
Customer Frame
802.1ad S-tagged Frame
802.1ah I-tagged Frame
ELS
PBB-TE
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Study assumptions
Study the impact on label usage of the following dimensions: Topology (CONNECTEDNESS) Traffic matrix (SIZE, UNIFORMITY) BW usage
NORMALIZATION: Tests have run 100 times Only one dimension has been changed in a time
Shortest Path Routing (Dijkstra hop count) is taken as base routing algorithm
Base topology of 100 nodes (connectedness +-2) & 1000 demands
AB
C
D
E
1 23
4-9
10i
ii
L
iii
x
a
b
L
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Connectedness of a network
Connectedness of a topology: what is the average node degree of a node in a topology: ring vs. full mesh
Example: Single (un-)connected 4-connected Full mesh
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Connectedness of the topology
0
50
100
150
200
250
300
350
400
450
500
0 10 20 30 40 50 60 70 80 90
Average node degree
lab
el
sp
ac
e r
eq
uir
ed
Link Local Link Local (bal.) Link Local (M)Node Local Node Local (bal.) Node Local (M)Global Global (SF)
S
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Connectedness vs BW (Luis)
The topology generator considered for generating the topologies in this section is IGEN
For all the topologies the link capacity is set to 10Gb/s and bandwidth request of 100Mb, 200Mb and 300Mb are generated until the network is overloaded.
The implemented algorithm is the SPF
Overload network with links of 10G capacity A
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Maximum number of labels
0
500
1000
1500
2000
2500
3000
3500
2 10 20 30 40 50 60 70 80 90 100
node degree
Labels per link
Labels per link with agg
Labels per link withagg+merging
Labels per destination
Labels per destinationwith agg
Labels per destinationwith agg_ VLAn reut
Labels per destinationwith agg+inv trees
Connectedness vs. BW (Luis)
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Maximum Number of Labels
0
10
20
30
40
50
60
2 10 20 30 40 50 60 70 80 90 100
node degree
Labels per link withagg+merging
Labels perdestination with agg_VLAn reut
Labels perdestination withagg+inv trees
Connectedness vs. BW (Luis)
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Maximum number of labels
020406080
100120140160180
number of nodes
Labels per link
Labels per link withagg
Labels per link withagg+merging
Labels per destination
Labels per destinationwith agg
Labels per destinationwith agg_ VLAn reut
Labels per destinationwith agg+inv trees
Topology size vs. BW (Luis)
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Topology size vs. BW (Luis)
Maximum number of labels
020406080
100120140160180
20 40 60 80 100
120
140
160
180
200
number of nodes
Labels per link
Labels per link withagg
Labels per link withagg+merging
Labels per destination
Labels per destinationwith agg
Labels per destinationwith agg_ VLAn reut
Labels per destinationwith agg+inv trees
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Uniformity of the traffic matrix
UNIFORMITY: X demands directed to 1 vs. x destinations?
Example: 4 demands 2 destinations vs 4 destinations
4 paths / 1 dest 4 paths / 2 dest 4 paths / 4 dest
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Uniformity of the traffic matrix
0
50
100
150
200
250
300
350
400
450
500
0 10 20 30 40 50 60 70 80 90 100
Number of nodes used as destination
lab
el
sp
ac
e r
eq
uir
ed
Link Local Link Local (bal.) Link Local (M)Node Local Node Local (bal.) Node Local (M)Global Global (SF)
S
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Size of the traffic matrix
The size of a traffic matrix affects the number of demands that are routed over a network:
10 demands 100 demands 1000 demands 10000 demands …
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Scaling the order of the traffic
0
50
100
150
200
250
300
350
400
450
500
0 1000 2000
Traffic streams
lab
el
sp
ac
e r
eq
uir
ed
Link Local Link Local (bal.) Link Local (M)Node Local Node Local (bal.) Node Local (M)Global Global (SF)
S
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Lookups Must be Fast
1. Lookup mechanism must be simple and easy to implement2. Memory access time is the bottleneck
200Mpps × 2 lookups/pkt = 400 Mlookups/sec → 2.5ns per lookup
Year Aggregate Line-rate
Arriving rate of 40B POS packets (Million pkts/sec)
1997 622 Mb/s 1.56
1999 2.5 Gb/s 6.25
2001 10 Gb/s 25
2003 40 Gb/s 100
2006 80 Gb/s 200
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Direct lookup in ELS vs PBB-TE
•ELS: •Label space is 12 bits•With 64b data, this is 256 K of memory. • Label space is private to one link • Therefore, table size can be “negotiated”
SVID/MPLS-label
Addre
ss
Memory
Data
(Outgoing Port, new SVID label)
Direct Memory Lookup
•PBB-TE: •Label space is 48+12 bits•With 64b data, this is 64 EiB of memory (2^60). • Label space is global•2^60 > 2^12, therefore cannot hold all addresses in table and use direct lookup, less efficient alternatives:•Hashing •Binary/Multi-way Search Trie/Tree
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Conclusion
The specific traffic matrix & topology used, clearly affect label usage
The uniformity of the traffic matrix affects PBB-TE-type domain-wide labelling: more uniform is better
The topology connectedness affects ELS-type link-local labelling: more connected is better
In typical metro-network with low node-degree, PBB-TE & ELS LL have similar performance
PBB-TE with SF and ELS with merging consistently score better than alternatives
Node local labelling techniques consistently score worse than alternatives.
The label length affects the memory space needed and accordingly affects cost and lookup speed
Vakgroep Informatietechnologie – Onderzoeksgroep IBCN
Appendices
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Carrier-Grade Ethernet challenges
Flat address space scalability of number of MAC addresses to be learned
Beyond 100k learned addresses per node seems challenging
Scalability in terms of number of VLANs 12-bit VLAN ID (VID): 4k VLANs possible network wide
STP cannot converge faster than worst case 20s sec (root failure)
Traffic Engineering (routing) constraint by tree based structure.
Limited OA&M
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
IP/ MPLS
ISP1
ISPn
Video
WWW
LargeCO
Level 2remotes
RegionalPOP
RU/MTU
Small CO /Level 1remotes
AggregationNetwork
[ring / star]
< 5,5 km< 1,5km 2,1 - 3,0 km
ADSL/ADSL2+
VDSL
FE/GigEor PON
ADSL
RAM /DLC
FE/GigE/SONET
CLE
BRAS
CustomerPremises
RegionalNetwork
BroadbandServices
Aggregator
AccessNetwork
[ring / star]
BNG
EthernetAggregation
(optional)
< 50 km
@ 50% penetration@ 10% penetration
# of lines
# of customers 50-50010-100
100-1K
100-2K20-400
200-4K
5K-10K
1K-2K
10K-20K
25K-50K
5K-10K
50K-100K
SDSL (business) FE/GigE/SONET/CDWM
OLT /CO DSLAM
Metro Core Core
Metro Aggregation
Metro Access
First Mile
Ethernet
Around 5 to 10 nodes
IP/ MPLS
ISP1
ISPn
Video
WWW
LargeCO
Level 2remotes
RegionalPOP
RU/MTU
Small CO /Level 1remotes
AggregationNetwork
[ring / star]
< 5,5 km< 1,5km 2,1 - 3,0 km
ADSL/ADSL2+
VDSL
FE/GigEor PON
ADSL
RAM /DLC
FE/GigE/SONET
CLE
BRAS
CustomerPremises
RegionalNetwork
BroadbandServices
Aggregator
AccessNetwork
[ring / star]
BNG
EthernetAggregation
(optional)
< 50 km
@ 50% penetration@ 10% penetration
# of lines
# of customers 50-50010-100
100-1K
100-2K20-400
200-4K
5K-10K
1K-2K
10K-20K
25K-50K
5K-10K
50K-100K
SDSL (business) FE/GigE/SONET/CDWM
OLT /CO DSLAM
Metro Core Core
Metro Aggregation
Metro Access
First Mile
Ethernet
Around 5 to 10 nodes
Reference network
AB
C
D
E
1 2
3
4-9
10i
ii
L
i
iix
a
b
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Assumptions (Luis)
Results are evaluated in terms of the maximum and average number of:
For ELS (average calculated based on the number of links): Labels per link Labels per link with agg (meaning only paths are count) Labels per link with agg and label merging
For PBB-TE Labels per destination Labels per destination with agg (meaning only paths are
count) Labels per destination with VLAN-reut (meaning link
disjoint paths can use same label) Labels per destination with INV-trees (paths that intersect
only on a common segment ending at the destination can also use the same label)B
Vakgroep Informatietechnologie – Onderzoeksgroep IBCN
Tests on smaller networks not normalized
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Uniformity in small 3-connected network
S
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Connectedness in 28n network
S
Label scalability & efficiency of Carrier Ethernet – Wouter TavernierVakgroep Informatietechnologie – Onderzoeksgroep IBCN
Traffic scaling in small network
0
2000
4000
6000
8000
10000
12000
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31
Nr of global labels
Nr of link local labels
Nr of node local
Nr of optimized link local
Nr of optimized node local
Global SF gain
Link local merge gain
Node local merging
S