Alcatel-Lucent 7750 SR OS Interface Configuration Manual page 419

The path cost is dynamically calculated based on the interface bandwidth. OSPF path cost can be
changed through the interface metric or the reference bandwidth.
If dynamic cost is configured, then costing is applied based on the total number of links configured
and the cost advertised is inversely proportional to the number of links available at the time. This is
provided that the number of links that are up exceeds the configured LAG threshold value at which
time the configured threshold action determines if, and at what cost, this LAG will be advertised.
For example:
If dynamic cost is not configured and OSPF autocost is configured, then costing is applied based on
the total number of links configured. This cost will remain static provided the number of links that are
up exceeds the configured LAG threshold value at which time the configured threshold action
determines if and at what cost this LAG will be advertised.
If dynamic-cost is configured and OSPF autocost is not configured, the cost is determined by the cost
configured on the OSPF metric provided the number of links available exceeds the configured LAG
threshold value at which time the configured threshold action determines if this LAG will be
advertised.
If neither dynamic-cost nor OSPF autocost are configured, the cost advertised is determined by the
cost configured on the OSPF metric provided the number of links available exceeds the configured
LAG threshold value at which time the configured threshold action determines if this LAG will be
advertised.
The no form of this command removes dynamic costing from the LAG.
Default
no dynamic-cost
encap-type
Syntax encap-type {dot1q | null | qinq}
no encap-type
Context config>lag
Description This command configures the encapsulation method used to distinguish customer traffic on a LAG.
The encapsulation type is configurable on a LAG port. The LAG port and the port member
encapsulation types must match when adding a port member.
If the encapsulation type of the LAG port is changed, the encapsulation type on all the port members
will also change. The encapsulation type can be changed on the LAG port only if there is no interface
associated with it. If the MTU is set to a non default value, it will be reset to the default value when
the encap type is changed.
The no form of this command restores the default.
Default
null — All traffic on the port belongs to a single service or VLAN.
Parameters
dot1q — Ingress frames carry 802.1Q tags where each tag signifies a different service.
7750 SR OS Interface Configuration Guide
Assume a physical link in OSPF has a cost associated with it of 100, and the LAG consists of
four physical links. The cost associated with the logical link is 25. If one link fails then the cost
would automatically be adjusted to 33.
Interface Configuration
Page 419