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Beginner

ME3400 SVI stats not reporting properly

I understand that unless the packets are pushed through CPU, the stats will not show up in a "show int vlan <xxxx>" command output as show below. Others have posted similar inquiries on this website with no real satisfactory solution. Every other switch I have ever dealt with(6500, 4948, 3560, 3750, 2900 series, etc, etc, etc.) have not had this issue. Is there a way to force "routed"/layer-3 packets to traverse the CPU in order to get the SVI stats needed? It seems strange that one switch would behave this way while all others do what we need them to do in order to report traffic correctly.

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Cisco Employee

Hi Robert,


what you see is a common behavior on almost all DSBU platforms (3750, me3750, me3400 etc) while you get those types of stats on GSBU (Cat4k) and ISBU/ERBU (cat6k/C7600) devices.



SVI's input and output packet counters will not increment for layer 3 packet forwarding between 
SVI interfaces in the hardware path. This behavior is
 a platform limitation. Bug CSCsi44166 explains that for the 3750 but the same reasoning applies
 for me3400 (same port asics). It is in fact
 due to the architecture of the switch, collecting this info from
 the ASICs would lead to a big performance impact.

For the same reason you would not want "to force "routed"/layer-3 packets to traverse 
the CPU in order to get the SVI stats needed" as it will come with
a big cost that is software switching which is neither wanted nor supported.

Hope this helps

RIccardo
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