Interface Configuration
7750 SR OS Interface Configuration Guide
Page 69
LAG
Based on the IEEE 802.3ad standard, Link Aggregation Groups (LAGs) can be configured to
increase the bandwidth available between two network devices, depending on the number of links
installed (from 1 to 8). LAG also provides redundancy in the event that one or more links
participating in the LAG fail. All physical links in a given LAG links combine to form one logical
interface.
Packet sequencing must be maintained for any given session. The hashing algorithm deployed by
Alcatel-Lucent SR-Series routers is based on the type of traffic transported to ensure that all traffic
in a flow remains in sequence while providing effective load sharing across the links in the LAG.
LAGs must be statically configured or formed dynamically with Link Aggregation Control
Protocol (LACP). The optional marker protocol described in IEEE 802.3ad is not implemented.
LAGs can be configured on network and access ports.
LAG Features
Hardware capabilities:
•
The LAG load sharing is executed in firmware, which provides line rate forwarding for all
port types.
Software capabilities:
•
In addition to the mandated IEEE LAG implementation, Alcatel-Lucent’s solution has
several improvements including dynamic costing and LAG port threshold features. The
dynamic cost and LAG port threshold features can be enabled even if the second node is
not an Alcatel-Lucent SR-Series router.
→
Dynamic cost
Dynamic cost can be enabled with the
config>lag
dynamic-cost
command or by the
action specified in the
config>lag port-threshold
command.
If dynamic cost is enabled and the number of active links is greater than the port
threshold value (0-7), then the path cost is dynamically calculated whenever there is a
change in the number of active links regardless of the specified port threshold action.
If the port-threshold is met and the action is set to dynamic cost, then the path cost is
dynamically recalculated regardless of the global dynamic cost configuration.
Enabling dynamic costing causes the physical link metrics used by OSPF to be
applied based on the operational or aggregate link bandwidth in the LAG that is
available at the time, providing the number of links that are up exceeds the configured
Summary of Contents for 7750 SR OS
Page 6: ...Page 6 7750 SR OS Interface Configuration Guide Table of Contents ...
Page 8: ...Page 8 7750 SR OS Interface Configuration Guide List of Tables ...
Page 10: ...Page 10 7750 SR OS Interface Configuration Guide List of Figures ...
Page 14: ...Preface Page 14 7750 SR OS Interface Configuration Guide ...
Page 16: ...Getting Started Page 16 7750 SR OS Interface Configuration Guide ...
Page 184: ...Card MDA and Port Command Reference Page 184 7750 SR OS Interface Configuration Guide ...
Page 438: ...Debug Commands Page 438 7750 SR OS Interface Configuration Guide ...
Page 444: ...Index Page 444 7750 SR OS Interface Configuration ...