Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Which is prioritized for multicast traffic if FastSwitching and CEF is enable?

                   Hello

Here is the related configuration and output of show command below,

In my understanding, there are 3 swtching mode, CPU, fast-swthing and CEF swthing,

But if FastSwthing and CEF swithing are enable both, then which swithing mode is prioritized for mutlicast traffic?

-----------------------------------------------------------

interface Vlan302

ip address 10.0.20.1 255.255.255.0

-----------------------------------------------------------

3750X#sh ip int vlan 302

Vlan302 is down, line protocol is down

  Internet address is 10.0.20.1/24

  Broadcast address is 255.255.255.255

  *omit

  IP fast switching is enabled

  IP Flow switching is disabled

  IP CEF switching is enabled

  IP CEF switching turbo vector

  IP Null turbo vector

  IP multicast fast switching is enabled

  IP multicast distributed fast switching is enabled

  IP route-cache flags are Fast, CEF

  *omit

-----------------------------------------------------------

interface Vlan301

ip address 10.0.10.1 255.255.255.0

no ip mroute-cache

-----------------------------------------------------------

3750X#sh ip int vlan 301

Vlan301 is down, line protocol is down

  Internet address is 10.0.10.1/24

  Broadcast address is 255.255.255.255

  *omit

  IP fast switching is enabled

  IP Flow switching is disabled

  IP CEF switching is enabled

  IP CEF switching turbo vector

  IP Null turbo vector

  IP multicast fast switching is disabled

  IP multicast distributed fast switching is disabled

  IP route-cache flags are Fast, CEF, No Distributed

  *omit

---

Product : Cat3750X

IOS version :  15.0(2)SE5

Best Regards,

Masanobu Hiyoshi

2 REPLIES
Super Bronze

Re: Which is prioritized for multicast traffic if FastSwitching

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

I'm not 100% certain, but I believe FastSwitching and CEF switching apply to unicast, not multicast.  Your "IP mroute-cache" command enables/disables fast multicast switching.

On a 3750, switching should be hardware based, for unicast and multicast, unless TCAM resources are insufficient.  If hardware switching falls back to non-hardware switching, you'll likely find process vs. Fast vs. CEF vs. multicast doesn't matter, all too slow.

New Member

Which is prioritized for multicast traffic if FastSwitching and

Hello

Thank you very much for this precious information.

I think if catalyst switch treats mulcast packet as fast-switching by using mroute-cache command.

if it is not using, CPU processing would be using them.

If it is correct, then performance is slightly difference between the multicast fast switching and CPU processing right?

Thank you and best regards,

Masanobu Hiyoshi

412
Views
0
Helpful
2
Replies
CreatePlease login to create content