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Nexus F & M card Routing working differnce:




I am confused between Routing abilities of M series and F series card card of Cisco Nexus.

F1 don't support Routing, F2e & F3 support routing

M series since initially support routing.


Now if F series (F2e & F3) and M series both card support routing... then what is difference between them?? 

6 Replies 6

Reza Sharifi
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Cisco Employee
Cisco Employee

The F series modules are a SoC (switch on chip) architecture while the M1/M2 are a centralized asic architecture. These two architectures afford different capabilities and limitations.


M1/M2 modules are capable of supporting larger routing/mac/acl tables as all resources are maintained for a central ASIC but there is some drop in throughput that you could see.


F series will split the front panel ports between an equal number of ASICs where each ASIC will maintain its own routing/mac tables but at a lesser value but we see a much higher increase in throughput capacity.


M3 modules have moved to a SoC architecture at this point. 

Thanks Clsulliv,


This is right ans but seems very short because many Qns arises


Can you tell or share some links what can help me to understand me first what is the logic or idea behind F and M series line cards.


if M3 modules have moved to a SoC architecture at this point...then what is the difference remained between F (F3) and M (M3) then.. if Cisco is making two different series of line cards there must be some measurable/feature/capacit/working nature/cost wise difference..


in short which cards are best F or M?

Exact which card is advised in what scenario or for what requirement ..

I think the best resource will be the data sheets. In past revisions the main trade off between the two was that F series would deliver better throughput while, M series would provide bigger buffers/tables. With M3 move to SoC, the M3 is able to match the throughput of F3 but is able to provide larger table sizes for MAC/Route and larger buffer sizes for packet storage.


The two linecards will also differ in what features are supported due to updates or changes in the ASIC. I believe that M3 supports 256 bit MACSEC across the board but there are restrictions against what ports it can be used on F3 and I do not think it can do 256 bit.


It really depends on what the N7K will be doing in a deployment for which would be best. If it is a DC core or SP where large route tables may be expected, the M3 is probably going to be a better purchase at this time due to its larger tables. 


It looks like the M3 is roughly double the cost of what the F3 is currently.

The biggest gripe (and Gotcha) when people purchased the N7K-F248XP-25 (aka standard F2) is one inability of this line card to work with M1/M2 and F1 card.  The F2 has be in it's own little VDC.   No one in Cisco would admit that this was due to an engineering fault (or disaster).

So the F2e was born.  Whatever the standard F2 can do, the F2e can do as well.  And the F2e can work with M1/M2.  And when this happens (as stated on the Data Sheet) "When deploying the Cisco Nexus 7000 F2e-Series Fiber Module in a VDC together with the Cisco Nexus 7000 M-Series modules, the Cisco Nexus 7000 F2e-Series Fiber Module will run in Layer 2-only mode, delegating all Layer 3 capabilities to the Cisco Nexus 7000 M-Series modules present in the VDC. The initial software release does not support this capability."

The F2e comes in two "shapes":  48-ports of either 1/10BaseTx or SFP/SFP+

Like the F2, the F2e will still not be able to support OTV (Integrating F2 Series Modules Into a Cisco Nexus 7000 Series System).

Due to the release of the new F2e card, expect Cisco to announce (in 6 months time) the end-of-sale of the standard F2 card.  (My own opinion, read below for Cisco Nexus 7000 Production Management Team rebuttal.)

II am not sure what Cisco will do to clients who mistakenly purchased the standard F2.  Will Cisco quietly allow them to trade or swap to F2e
the F2e card cannot do routing by itself. It needs to proxy route off of a "M" card of some sort in the same VDC to create SVI's.

Cisco Employee
Cisco Employee

Nice question ...


Basically we have different types of M and F line cards as you can see the reply from one person with the sheet for the reference, if you are looking for basic difference then just follow me...


M  - basically an L3 line card used for routing purpose


F - Basically an L2 line card when it was introduced and higher versions of F line card can also support L3. 


M  Series Line card :

All line card support OTV

All line card support VPC

FCOE - Fabric Channel Over Ethernet and fabric path is not supported. 

N7K-M132XP-12L and 12 of M1 and all M2 line cards supports FEX not others. 


F series Line Card :

All line card support VPC

Only F3 line card support OTV , LISP and MPLS

FCOE - Fabric Channel Over Ethernet and fabric path is supported. 


If you found my answer to be useful please do not hesitate click on the Star button and answered.
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