ME3400E vs 881

[johnelliot6]

Hi Everyone,

Have a customers site where there is an 881 and also a ME3400E - ME3400E currently only does L2.

The customer is wanting to remove the 881, and have the ME3400E do all the L3 (And L2) functions - The ME is running metroipaccess (So can do L3), and I believe you need to adjust the SDM template (to sdm prefer default) for optimal routing performance.

The question is, what are the major differences in L3 between the Me3400 + 881?  Performance, Features etc?

Currently, the ME3400 accepts 2 VLANs from a  carrier - Trunks 1 vlan to the customers switch(L2 between 2 sites), and the other to the 881 for L3 to there LAN - It(ME3400) is also performing egress shaping on the port that connects to the carrier.

Thanks in advance.

[daniel.dib]

The ME device is primarily a switch for Metro networks and the 881 is a CPE. The 881 can do NAT, firewalling, NBAR and probably some other things I would not expect the ME to be able to do.

Daniel Dib
CCIE #37149

[Joseph W. Doherty]

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Posting

The question is, what are the major differences in L3 between the Me3400 + 881?  Performance, Features etc?

Yep, tha't the principle difference, i.e. "Performance" (ME3400) vs. "Features" (881).  (NB: BTW, Cisco recommends the 880 series for up to 8 Mbps WAN [duplex] bandwidth.)

... and I believe you need to adjust the SDM template (to sdm prefer default) for optimal routing performance.

Maybe, maybe not.  Really depends on size of route table.  SDM template adjust TCAM resources for different purposes.

[johnelliot6]

Thanks Joseph - Based on the following:  http://www.cisco.com/en/US/docs/switches/metro/me3400/software/release/12.2_46_se/configuration/guide/swsdm.html

Looks like in "L2" mode, L3 is punted to CPU(So poor L3 performance), and in "Default" L3 isnt punted...It doesnt mention if "Default" impacts on L2 performance though..(It does state that if a hardware resource is full, it will be punted to CPU, so I read this as some L2 may perform poorly also in "Default"?)

So, if we are not doing any NAT, complicated QOS etc, the ME3400 "should" be ok?

Layer-2—The layer-2 template maximizes system resources for Layer 2 functionality and does not support routing. You should use this template when the switch is being used for Layer-2 forwarding. When you select the layer-2 template on a switch running the metro IP access image, any routing is done through software, which overloads the CPU and severely degrades routing performance.

•Default—The default template gives balance to all functions: Layer 2 and Layer 3 (routing). This template is available only on switches running the metro IP access image. If you do not use the default template when routing is enabled on the switch, any routing is done through software, which overloads the CPU and severely degrades routing performance.

Cheers.

[Joseph W. Doherty]

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

(Hmm, somehow lost a reply - maybe I forgot to hit post button - oh well, try again . . .)

Looks like in "L2" mode, L3 is punted to CPU(So poor L3 performance), and in "Default" L3 isnt punted...It doesnt mention if "Default" impacts on L2 performance though..(It does state that if a hardware resource is full, it will be punted to CPU, so I read this as some L2 may perform poorly also in "Default"?)

Yes, your L2 performance would be impacted if you have more than 5K (rather than 8K) MACs, see your table 6-1 in your reference.

So, if we are not doing any NAT, complicated QOS etc, the ME3400 "should" be ok?

Yes, it should be okay.