By default, only the MEDs of routes that have the
same peer ASs are compared. You can configure routing table path selection
options to get different behaviors. To configure routing table path
selection behavior, include the path-selection statement:
For a list of hierarchy levels at which you can
include this statement, see the statement summary section for this
Routing table path selection can be configured
in one of the following ways:
Using the same nondeterministic behavior as does the Cisco
IOS software (cisco-non-deterministic). This behavior has
The active path is always first. All nonactive, but eligible,
paths follow the active path and are maintained in the order in which
they were received, with the most recent path first. Ineligible paths
remain at the end of the list.
When a new path is added to the routing table, path comparisons
are made without removing from consideration those paths that should
never be selected because those paths lose the MED tie-breaking rule.
These two effects cause the system to only sometimes
compare the MEDs between paths that it should otherwise compare. Because
of this, we recommend that you not configure nondeterministic behavior.
Always comparing MEDs whether or not the peer ASs of the
compared routes are the same (always-compare-med).