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(IEEE 802.3ad)
Link Aggregation
Load Balance Example
Applications
Feature Review
Advantages
Definition
Agenda
Agenda
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a load balancing function
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Traffic sent to the ports in such a group is distributed through
instances of full duplex point-to-point links operating at the
same data rate
The Link Aggregation Group is consisting of N parallel
together to form a Link Aggregation Group, such that a MAC
Client can treat the Link Aggregation Group as if it were a
single link
Link Aggregation allows one or more links to be aggregated
IEEE Definition:
Introduction to Link Aggregation
Advantages
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100 Mbps
The capacity of the multiple links is combined into one logical link.
Link Aggregation allows the establishment of full duplex point-to-point links
that have a higher aggregate bandwidth than the individual links that form the
aggregation.
1. Increased aggregate bandwidth
Benefits of using Link Aggregation
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Traffic via LAG is distributed according to users policy improved reliability
In case of a failed link, remaining links take over utilization of new available BW
2. Improved Resiliency
Benefits of using Link Aggregation
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STP requires blocking and
path cost calculations
With LA STP or routing protocols are not needed, therefore, less processing is involved.
When multiple ports are allocated between 2 Routers, Routing Protocols are required to
control traffic paths.
When multiple ports are allocated between two ETH switches, broadcast storms are
created due to physical loops. STP is required to eliminate loops by blocking the redundant
port.
3. Reduced Complexity & Administration
Benefits of using Link Aggregation
>> we trunk N x FE ports
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Instead of utilizing an expensive GbE port(s) to transport 200Mbps
4. Reduced Cost
Benefits of using Link Aggregation
Multiple
Interfaces
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Customer
Network
Single
Interface
(These examples refer to using L2 topologies as well)
Public
Network
For sites that need to hide the existence of internal interfaces, the IP address of
the aggregation hides its interfaces from external applications.
For sites with limited IP address space that nevertheless require large amounts of
bandwidth, you need only one IP address for a large aggregation of interfaces.
5. Improved Network Efficiency / Security
Benefits of using Link Aggregation
Feature Review
11
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This provides better statistical load balancing.
2. Hash (default):
In this method the hash function (used by the traffic switch for address table lookups)
is used to select one of the ports in the group.
This method can be used for testing & debugging.
1. Simple XOR:
In this method the 3 LSBs of DA and SA are XORed and the result is used to select
one of the ports in the group.
Two methods are available for Link Aggregation Group traffic distribution:
Traffic sent to ports in a group is distributed through a load balancing function.
LAG Distribution Policy
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MAC (HEX)
00:20:8f:0a:02:01
00:20:8f:0a:01:01
00:20:8f:0a:02:02
00:20:8f:0a:01:02
00:20:8f:0a:02:03
00:20:8f:0a:01:03
00:20:8f:0b:e1:03
00:20:8f:0a:e1:04
00:20:8f:0b:e1:03
00:20:8f:0a:e1:01
00:20:8f:0b:e1:07
00:20:8f:0a:e1:04
Stream
SA ->
- > DA
SA ->
- > DA
SA ->
- > DA
SA ->
- > DA
SA ->
- > DA
SA ->
- > DA
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111
100
010
101
011
010
011
011
010
010
001
001
Last 3 bits
(Configure your Traffic Generator with the following MACs)
011 (3)
010 (2)
001 (1)
000 (0)
000 (0)
000 (0)
XOR result
Link #4
Link #3
Link #2
Link #1
Link #1
Link #1
Assigned LAG Port
We can easily demo balanced traffic distribution using the XOR method
LAG Distribution: Simple XOR
13
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7. A LAG may contain from 1 to 5 physical ports
6. There may be up to 3 LAGs per IDU
5. All ports in a LAG must be in the same IDU (same switch)
4. LAG is not supported in a Single Pipe mode
3. LAG is supported in IDUs configured as Managed or Metro switch
2. Management ports / WSC ports cannot be grouped in a LAG
1. Only traffic ports (including radio port) can belong to a LAG
Static LAG guidelines
14
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11. Dynamic Link Aggregation (LACP) is not supported
10. The LAG will initially receive default values for these parameters
xSTP role (edge, non-edge)
path cost
9. When a LAG is created, it will automatically inherit all the ports
characteristics, except for the following:
8. LAGs are virtual ports that do not permanently exist in the system
Static LAG guidelines (continued)
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FE
GbE
8
IP-10 IDU
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GbE
FE
8
IP-10 IDU
Ports 1-2 (GBE ports) and ports 3-7 (FE only ports) cannot be in the same LAG
group even if the GBE ports are configured as 100Mbps.
Grouping ports in LAG
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FE
GbE
8
IP-10 IDU
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GbE
Radio port (port 8) may be in a LAG with the GBE ports only
Grouping ports in LAG
FE
8
IP-10 IDU
Applications
18
GbE
PHY
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Multiple Radio System
implemented with LAG
Port #2 and Radio
form a LAG
Single Pipe
Stackable
(Nodal) Site
GbE
PHY
Multiple FE
ports as a LAG
Standalone Site
Multiple PHYs are grouped together to support a higher capacity PHY.
Grouped ports are known as LAG Link Aggregation Group.
Introduction to Link Aggregation
3rd party
Switch or Router
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Dual (redundant) GbE interfaces facing the Switch/Router
Static Link Aggregation Group (or equivalent) configured on the Switch/Router
interfaces connected to the IP-10
Any failure in the local GbE interfaces will be handled by the link aggregation mechanism
Static LAG
1+0 LAG
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No need for LAG
1+1 HSB or
2+0 Multi-Radio
(traffic interruption <50mSecs)
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MW Radio link switchovers are transparent to Switch/Router
STBY IP-10 GbE interface is disabled
Optical splitter/combiner is used to connect to each of the IP-10 GbE interfaces in
(1+1) protected configuration
Single GE interfacing a 3rd party Switch/Router
3rd party
Switch or Router
1+1 HSB W/O LAG
Static LAG
No need for LAG
1+1 HSB or
2+0 Multi-Radio
21
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Dual (redundant) GE interfaces facing the 3rd party Switch/Router
Static Link Aggregation Group (or equivalent) is configured on the Switch/Router
interfaces connected to the IP-10 units
STBY IP-10 disables its Ethernet interface towards the Switch/Router
As a result, the Switch/Router sends all traffic over the Ethernet interface connected to
the active IP-10
Any failure detected in radio link or Ethernet interface will trigger a switch-over to the
back-up unit with <50msecs traffic interruption on the radio link
The Switch/Router detects the switch-over and start sending traffic over the interface
connected to the new active unit only
3rd party
Switch or Router
1+1 HSB With LAG
Static LAG
1+1 HSB or
2+0 Multi-Radio
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Dual (redundant) GE interface to the Switch/Router
Static Link Aggregation Group (or equivalent) is configured on the Switch/Router
interfaces connected to the IP-10s
Static Link Aggregation Group (or equivalent) is configured on the IP-10
2 optical splitter/combiners are used to connect each of the 2 interfaces on the
Switch/Router to each of the corresponding interfaces on the IP-10s
3rd party
Switch or Router
Static LAG
Static LAG
1+1 HSB With dual GbE + LAG
Static LAG
1+1 HSB or
2+0 Multi-Radio
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Any failure in the local GbE interfaces will be handled by the link aggregation
mechanism without triggering switch-over to the back-up IP-10 unit!
STBY IP-10 disables its Ethernet interface towards the Switch/Router
Any failure detected in radio link or equipment will trigger switch-over to the back-up
IP- 10 unit with <50msecs traffic interruption on the radio link
3rd party
Switch or Router
Static LAG
Static LAG
1+1 HSB With dual GbE + LAG (cont.)
Load Balance Example
25
Port #2 and Radio
form a LAG
50%
50%
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GbE port #1 = (50% via Radio #1) + (50% via Radio #2)
Traffic injected via GbE port #1 is distributed evenly between Port #2 & Port #8
Port #2 is linked to a Pipe IDU, hence, a Multi-Radio system is achieved:
IDU #2 is configured as Single Pipe
IDU #1 is configured as Managed Switch to support LAG
GbE
PHY
Load balance example
26
1)
2)
3)
4)
5)
P
1
4) Port 2 is out
of the LAG
2) Alarm is
propagated
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Enable Automatic State Propagation on both IDUs
Radio #2 encounters a signal degradation
Since ASP is enabled, the alarm is propagated to port #1
IDU #1 detects the alarms and shuts down port #2
Port #2 is not part of the LAG
Radio #1 takes full control (100%) of traffic
GbE
PHY
3) Port 1 is
shut down
Load balance example
100%
5) Radio 1
takes 100%
X
50%
1) Link
Degradation
Shut down
100%
X
50%
64QAM
100%
256QAM
27
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To improve system resiliency, Automatic State Propagation can shut down the
LAG interface when ACM degrades below a pre-determined profile.
GbE
PHY
Load balance example
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training@ceragon.com
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