IOS to Junos (I2J) Tips
IOS to Junos (I2J) Tips

OSPF route summarization.

[ Edited ]
‎04-05-2012 01:39 PM


   Hi all.

   Here you will find the differences between the Cisco ospf route summarization, and the JunOS summarization.
 
   At IOS under OSPF, summarization could be accomplished with two different commands, summary address and area range. summary only works for external routes, and area range for intra area routes, both applied at the abr boundary.


   Summary and range are applied on any non stub area, where there is routes redistribution inside.

 

   The main differences with JunOS :

 

    IOS have two commands, summary for external area range for intra area.
    JunOS have only one, area range. No way to mistakes.

 

    IOS summary is applied under the router ospf hierarchy, no area specification.
    Junos area range is applied under the incoming ospf area. There is a special case, for NSSA areas, the area range must configured under the nssa hierarchy as i will show later, if not summarization will not work.

    This way the JunOS range will be applied only that area, will not apply on other area routes.

 

    Both ios and junos have a "dont advertise" option for summary or area range.

    For ios and junos area range, a cost could be applied to the new summary route, but not under the ios summary address command.

 

    Summarization have the same behavior, for external routes, summary hides the more specific routes. If the "dont advertise" option is configured then both specific routes and summary will not be advertised.
 

   For internal routes, summary dont hide the more specific routes. "dont advertise" will only affect the summary, specific routes will be propagated anyway.

 

 

 

 

 ---------------------------------------------------------------------------------------------------------------------------
 IOS configuration
----------------------------------------------------------------------------------------------------------------------------


 !
 ! R1, area nssa 1.1.1.1 intra area router.
 !

 !
 ! This interface will be redistributed into nssa area.
 !
 interface Loopback0
  ip address 10.1.2.1 255.255.255.0 secondary
  ip address 10.1.3.1 255.255.255.0 secondary
  ip address 10.1.4.1 255.255.255.0 secondary
  ip address 10.1.1.1 255.255.255.0

 !
 interface fastethernet0/0
         description Link to R2 ABR router.
         ip address 12.12.12.1 255.255.255.0
 !
 !
 !
 router ospf 1
  router-id 10.1.1.1
  log-adjacency-changes
  area 1.1.1.1 nssa
 !
 ! Interface loopback 0 redistribution into ospf.
 !
  redistribute connected subnets
 !
  network 12.12.12.0 0.0.0.255 area 1.1.1.1


 !
 ! R2 , ABR router. Summary configuration under ospf.
 !

 interface fastethernet0/0
  description Link to R1 intra area Router.
   ip address 12.12.12.2 255.255.255.0

 interface fastethernet0/1
   description Link to R3 ABR router.
   ip address 23.23.23.2 255.255.255.0

 !
 ! External routes summarization for nssa area.
 !
 router ospf 2
  log-adjacency-changes
  area 1.1.1.1 nssa
 !
 ! Networks 10.1.x.x will be received from R1 in area 1.1.1.1
 ! External networks will be summarized with summary-address.
 !
  summary-address 10.1.0.0 255.255.252.0
 !
  network 10.2.0.0 0.0.255.255 area 0.0.0.0
  network 12.12.12.0 0.0.0.255 area 1.1.1.1
  network 23.23.23.0 0.0.0.255 area 0.0.0.0

 !
 ! R3 , ABR router. Intra area routes summarization.
 !

 interface fastethernet0/0
  description Link to R4 intra area router.
  ip address 34.34.34.3 255.255.255.0

 interface fastethernet0/1
  description Link to R2 ABR router.
  ip address 23.23.23.3 255.255.255.0

 !
 ! External routes summarization for nssa area.
 !
 router ospf 3
  router-id 10.3.1.1
 !
 ! Networks 10.4.x.x will received from R4 in area 2.2.2.2
 ! Internal networks that will be summarized with area range.
 !
  area 2.2.2.2 range 10.4.0.0 255.255.252.0
 !
  network 23.23.23.0 0.0.0.255 area 0.0.0.0
  network 34.34.34.0 0.0.0.255 area 2.2.2.2

 

 !
 ! R4, intra area router.
 !
 interface fastethernet0/0
   description Link to R2 ABR router.
    ip address 34.34.34.4 255.255.255.0


 interface Loopback0
  ip address 10.4.2.1 255.255.255.0 secondary
  ip address 10.4.3.1 255.255.255.0 secondary
  ip address 10.4.4.1 255.255.255.0 secondary
  ip address 10.4.1.1 255.255.255.0


 router ospf 4
  router-id 10.4.1.1
  network 10.4.0.0 0.0.255.255 area 2.2.2.2
  network 34.34.34.0 0.0.0.255 area 2.2.2.2

 

 

 

 ---------------------------------------------------------------------------------------------------------------------------
 JunOS configuration
----------------------------------------------------------------------------------------------------------------------------

 /*
           R1 area nssa 1.1.1.1 router configuration.
 */
 
 /* Redistribute connected policy */
 set policy-options policy-statement CONN-R1 from protocol direct
 set policy-options policy-statement CONN-R1 then accept

 

/* This interface will be redistributed into OSPF */
 set interfaces lo0 unit 0 family inet address 10.1.1.1/24
 set interfaces lo0 unit 0 family inet address 10.1.2.1/24
 set interfaces lo0 unit 0 family inet address 10.1.3.1/24 
 set interfaces lo0 unit 0 family inet address 10.1.4.1/24

 

 set interfaces ge-0/0/0 description "Link to R2 ABR router."
 set interfaces ge-0/0/0 unit 0 family inet address 12.12.12.1/24


 set routing-options router-id 10.1.1.1

 

 /* Connected routes redistribution */
 set protocols ospf export CONN-R1

 

 set protocols ospf area 1.1.1.1 nssa
 set protocols ospf area 1.1.1.1 interface ge-0/0/0.0

 

 

 

 /*
           R2 ABR router configuration.
 */

 set interfaces ge-0/0/0 description "Link to R1 area 1.1.1.1 router."
 set interfaces ge-0/0/0 unit 0 family inet address 12.12.12.2/24
 set interfaces ge-0/0/1 description "Link to R3 ABR router."
 set interfaces ge-0/0/1 unit 0 family inet address 23.23.23.2/24


 set routing-options router-id 10.2.2.2

 

 /* R1 external routes summarization under nssa hierarchy. Networks 10.1.x.x received from R1. */
 set protocols ospf area 1.1.1.1 nssa area-range 10.1.0.0/22

 

 set protocols ospf area 1.1.1.1 interface ge-0/0/0.0
 set protocols ospf area 0.0.0.0 interface ge-0/0/1.0

 

 


 /*
           R3 ABR router configuration.
*/

 set interfaces ge-0/0/0 description "Link to R4 area 2.2.2.2 router."
 set interfaces ge-0/0/0 unit 0 family inet address 34.34.34.3/24
 set interfaces ge-0/0/1 description "Link to R2 ABR router."
 set interfaces ge-0/0/1 unit 0 family inet address 23.23.23.3/24

 

 set routing-options router-id 10.3.3.3
 set protocols ospf area 0.0.0.0 interface ge-0/0/1.0

 

 /* R1 external routes summarization under area hierarchy. Networks 10.4.x.x received from R4. */
 set protocols ospf area 2.2.2.2 area-range 10.4.0.0/22

 

 set protocols ospf area 2.2.2.2 interface ge-0/0/0.0

 

 

 

 /*
           R4 area 2.2.2.2 router configuration.
 */

 set interfaces lo0 unit 4 family inet address 10.4.4.4/24
 set interfaces lo0 unit 4 family inet address 10.4.1.4/24
 set interfaces lo0 unit 4 family inet address 10.4.2.4/24
 set interfaces lo0 unit 4 family inet address 10.4.3.4/24

 

 set interfaces ge-0/0/0 description "Link to R3 ABR router."
 set interfaces ge-0/0/0 unit 0 family inet address 34.34.34.4/24

 

 set routing-options router-id 10.4.4.4
 set protocols ospf area 2.2.2.2 interface lo0.4
 set protocols ospf area 2.2.2.2 interface ge-0/0/0.0

 

 

 

Br
Alex

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