Several concept issue ???

Answered Question
Aug 24th, 2009
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HI,dear all:

Can anyone tell me what's the different between CEF per-packet\CEF per-destination\fast switching\process switching ? I have a little faint :-(

Are there any doc to explain them or reference?

Many tks... :-)


Correct Answer by Mohamed Sobair about 7 years 9 months ago


Hi,


The packet forwarding/switching is done using one of the following method:


1- Process Switching


2- Fast Switching


3- CEF Switching


4- ASIC (Application Specific Integrated Circuit).


---


1- With (Process Switching), the packets are forwarded to the CPU and the CPU performs Switching , its often called Software Switching as the Switching is done on software basis.


2- With (Fast Switching), a Fast Switching table is created on a router On demand.


3- With (CEF Switching), the RIP table is copied into the CEF FIB once the router starts up, CEF Swirching is a topology driven.


CEF Switching has two tables:


a- The Adjacency table

b- The FOrward Information Base Table.



CEF Loadbalancing:


CEF performs Load balancing in two ways:


a- CEF load Balancing Per destination/prefix


b- CEF load balancing per packet



The default CEF loadbalancing Scheme is (Per Destination), However, Per packet load balancing is not recommended because

packet might arive at destination out of order.



4- With (ASIC) Application Specific Integrated Circuit, the hardware is correctly programmed to handle the packet switching.


Here is Some characterstics about IP Switching methods:


http://www.cisco.com/en/US/tech/tk827/tk831/technologies_white_paper09186a00800a62d9.shtml#fast



HTH

Mohamed

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Correct Answer
Mohamed Sobair Tue, 08/25/2009 - 01:17
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Hi,


The packet forwarding/switching is done using one of the following method:


1- Process Switching


2- Fast Switching


3- CEF Switching


4- ASIC (Application Specific Integrated Circuit).


---


1- With (Process Switching), the packets are forwarded to the CPU and the CPU performs Switching , its often called Software Switching as the Switching is done on software basis.


2- With (Fast Switching), a Fast Switching table is created on a router On demand.


3- With (CEF Switching), the RIP table is copied into the CEF FIB once the router starts up, CEF Swirching is a topology driven.


CEF Switching has two tables:


a- The Adjacency table

b- The FOrward Information Base Table.



CEF Loadbalancing:


CEF performs Load balancing in two ways:


a- CEF load Balancing Per destination/prefix


b- CEF load balancing per packet



The default CEF loadbalancing Scheme is (Per Destination), However, Per packet load balancing is not recommended because

packet might arive at destination out of order.



4- With (ASIC) Application Specific Integrated Circuit, the hardware is correctly programmed to handle the packet switching.


Here is Some characterstics about IP Switching methods:


http://www.cisco.com/en/US/tech/tk827/tk831/technologies_white_paper09186a00800a62d9.shtml#fast



HTH

Mohamed

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