Changing the RFC 1583 OSPF compliance setting

Changing external route preference compatibility from RFC 1583 to RFC 2328

In OSPF domains supporting multiple external routes from different areas to the same external destination, multiple AS-external-LSAs advertising the same destination are likely to occur. This can cause routing loops and the network problems that loops typically generate. On the routing switches, if RFC 1583 compatibility is disabled, the preference rules affecting external routes are those stated in RFC-2328, which minimize the possibility of routing loops when AS-external-LSAs for the same destination originate from ASBRs in different areas. However, because all routers in an OSPF domain must support the same routing-loop prevention measures, if the domain includes any routers that support only RFC 1583 preference rules, all routers in the domain must be configured to support RFC 1583.


The routing switch is configured, by default, to be compliant with the RFC 1583 OSPF V2 specification. (Use show ip ospf general to view the current RFC 1583 configuration setting.)

All routes in an AS should be configured with the same compliance setting for preference rules affecting external routes. Thus, if any routers in an OSPF domain support only RFC 1583, all routers must be configured with 1583 compatibility. In the default OSPF configuration, RFC 1583 support is enabled for the routing switches.

If all routers in the domain supportRFC 2178 or RFC 2328, you should disable RFC 1583 compatibility on all of the routers, because conformance to these later RFCs provides more robust protection against routing loops on external routes.


[no] rfc1583-compatibility

Executed at the global configuration level to toggle routing switch operation compliance between RFC 1583 and RFC 2328.


Configures the routing switch for external route preference rules compliant with RFC 1583.

no rfc1583-compatibility

Configures the routing switch for external route preference rules compliant with RFC 2328.

Default: Compliance enabled


To disable RFC 1583 compatibility on a routing switch in an OSPF domain where RFC 2178 and RFC 2328 are universally supported:

switch(config)# router ospf 
switch(ospf)# no rfc1583-compatibility
Switch(config)# router ospf 
Switch(ospf)# no rfc1583-compatibility 
Switch(ospf)# show ip ospf general

  OSPF General Status
   OSPF protocol              :enabled
   Router ID                  :
   RFC 1583 compatibility     :non-compatible

   Intra-area distance        :110
   Inter-area distance        :110
   AS-external distance       :110

   Default import metric      :10
   Default import metric-type:external type-2

   Area Border                :no
   AS Border                  :yes
   External LSA Count         :9
   External LSA Checksum Sum  :408218
   Originate New LSA Count    :24814
   Receive New LSA Count      :14889