Administering TCP/IP
Managing the Open Shortest Path First (OSPF) protocol
MAX Administration Guide
7-41
•
Connected routes, such as Ethernet, have
Preference=0
.
•
Routes learned from Internet Control Message Protocol (ICMP) redirects have
Preference=30
.
•
Routes placed in the table by SNMP MIB II have
Preference=100
.
•
Routes learned from OSPF have a default of
Preference=10
. Modify the default in
Ethernet > Mod Config > Route Pref.
•
Routes learned from RIP have a default of
Preference=100
. Modify the default in
Ethernet > Mod Config > Route Pref.
•
A statically configured IP Route or Connection profile has a default of
Preference=100
. Modify the default in the Connection or IP Route profile.
When choosing which routes should be put in the routing table, the router first compares the
Preference values, preferring the lowest number. If the Preference values are equal, the router
compares the Metric field and uses the route with the lowest Metric.
If multiple routes exist for a given address and subnet mask pair, the route with the lowest
Preference is best. If two routes have the same Preference, then the lower Metric is better. The
best route by these criteria is that actually used by the router. The others remain latent, or
hidden, in case the best route is removed.
To assign a WAN link the same preference as a route learned from OSPF:
1
Open Connections > IP Options.
2
Specify a Preference value of 10 (the default value for OSPF routes). For example:
Ethernet
Connections
40-101
Cprofile1
IP options…
LAN Adrs=10.9.8.10/22
WAN Alias=0.0.0.0
IF Adrs=0.0.0.0
Preference=10
Metric=5
DownPreference=
DownMetric=
...
....
...
3
Close the Connection profile.
On Ethernet, the route preferences also include ASE-type and ASE-tag information for routes
learned from RIP. These values affect all RIP information learned across the Ethernet. To
change the route preferences on Ethernet:
1
Open Ethernet > Mod Config > Route Pref.
2
Modify the parameters to adjust Preference values. For example, the following profile
assigns static routes the same Preference value as those learned from OSPF:
Ethernet
Mod Config
Route Pref...
Static Preference=10