L2 vs L3 throughput capacity

Unanswered Question
Sep 15th, 2010

Hi all,

I have a question with regard to L2 and L3 throughput capacity. Let's say I have a 3750G which has 32 Gbps switching fabric. Does this mean 32 Gbps at L2 only or L3 as well? For example, I have 20 SVIs configured on the switch (as opposed to running everything on single VLAN) and I want to use the switch itself to route between all of those VLANs. Does this affect the switch forwarding rate between different VLANs?

Thanks in advance. 

I have this problem too.
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Jon Marshall Wed, 09/15/2010 - 18:45

paul.stajewski wrote:

Hi all,

I have a question with regard to L2 and L3 throughput capacity. Let's say I have a 3750G which has 32 Gbps switching fabric. Does this mean 32 Gbps at L2 only or L3 as well? For example, I have 20 SVIs configured on the switch (as opposed to running everything on single VLAN) and I want to use the switch itself to route between all of those VLANs. Does this affect the switch forwarding rate between different VLANs?

Thanks in advance. 

Paul

On a L3 switch both L2 and L3 switching are performed in hardware using dedicated ASICs so there is very little difference between the 2 as long as the packet is being switch with CEF. Where you can get performance hits is if a lot of the packets are forwarded to the main CPU rather than being hardware switched but in general the performance of 32Gbps switching fabric applies to both L2 and L3.

Jon

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