Инструкции По Установке для 3com S7906E

 

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Route summarization: An ABR or ASBR summarizes routes with the same prefix into a single route and 

distribute it to other areas. 

Through route summarization, routing information across areas and the size of routing tables on routers 

will be reduced, improving calculation speed of routers. 

Assume in an area are three internal routes 19.1.1.0/24, 19.1.2.0/24, and 19.1.3.0/24. By configuring 

route summarization on the ABR, the three routes are summarized into the route 19.1.0.0/16 that is 

advertised into other areas. 

If contiguous network segments are available in the area, you can summarize them into a single 

network segment. An ABR generates Type-3 LSAs on a per network segment basis for an attached 

non-backbone area. 

In this way, the ABR in the area distributes only the summary LSA to reduce the scale of LSDBs on 

routers in other areas and the influence of topological changes. 

Follow these steps to configure route summarization on an ABR: 

Enter system view 

— 

Enter OSPF view 

ospf [ process-id | router-id 
router-id | vpn-instance 
instance-name ] * 

— 

Enter OSPF area view 

area area-id 

— 

Configure ABR route 
summarization 

abr-summary ip-address { mask 
| mask-length } [ advertise | 
not-advertise ] [ cost cost ] 

Required 

The command is available on 
an ABR only.  

Not configured by default. 

 

If summarization for redistributed routes is not configured on an ASBR, it will advertise each 

redistributed route in a separate ASE LSA. After a summary is configured on the ASBR, it advertises 

only the summary route in an ASE LSA instead of more specific routes, thus reducing the number of 

LSAs in the LSDBs. 

If summarization for redistributed routes is configured on an ASBR, it will summarize redistributed 

Type-5 LSAs that fall into the specified address range. If the ASBR is in an NSSA area, it also 

summarizes Type-7 LSAs that fall into the specified address range. If the ASBR is also the ABR, it will 

summarize Type-5 LSAs translated from Type-7 LSAs. 

Follow these steps to configure route summarization when redistributing routes into OSPF on an ASBR: 

Enter system view 

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