M series card architecture - Cisco Nexus 7000

M-series card is used for L3 purpose like routing ACLs. We must have at least one M1 card in the chassis to get the routing or L3 facility. Otherwise we cannot create SVI s and do inter vlan communication.

To check the available model and their feature, please refer

 http://netterrene.blogspot.in/2014/09/difference-between-m-series-and-f.html

Below is the architecture of the M-series card. Please note different M-series cards can have the different architecture.

Below is the architecture diagram of N7K-M132XP-12, N7K-M132XP-12L.

The components are explained below:-

FABRIC :- It is not the fabric on chassis but each card has its own fabric which connects the Module to the backplane fabric cards. Number of fabric present varies as per the cards.

More number of fabrics present in the card more backplane throughput card is. Each fabric has five interfaces to connect to the chassis fabric cards.

FORWARDING ENGINE:- All packet forwarding decision on th card are taken by forwarding engine. It stores the FIB and TCAM table and take the packet flow decision.

REPLICATION ENGINE:- It is used to replicate the packets as and when required. It is not only used while port mirroring but also when the card receives the multicast, broadcast or unknown broadcast.

Since the same replication engine is responsible for multicast, there is a limit on the packet replication that a card can handle so if the multicast replication is extremely high it can choke the replication engine, although it will never happen in normal circumstances.

VOQs :- VOQs stand for VIRTUAL OUTPUT QUEUE. It is a high speed memory to queue the packets so that it will not overrun the fabric. VOQs are controlled by central arbitrator siting in the supervisor module.

Its basic function is to  provide  buffering and queuing

EOBC:- EOBC stands for ETHERNET OUT-OF-BAND CHANNEL. Supervisor module has 24 port local switch and through this it is connected to each line card and fabric modules. It is of 1 gig capacity.

EOBC is used to connect local CPU on line card to both supervisor modules and the other line cards. Each line card has two EOBC connections to the supervisor module.

LC CPU :-  Each Line has its own in build small CPU. And it is connected to the Supervisor CPU via EOBC

10G Mac:- It receives the packet from the interface and then encode the data and send it to replication engine

4:1 MUX + LINKSEC: - It  does the  multiplexing and de-multiplexing job  of the data coming in or out from the four ports to the one 10Gig connectivity to the backplane. This over subscription varies as per the card model. It also performs the function of linksec and encodes and decodes the data.

 Central arbitration: – It controls the traffic coming in/out the Cross fabric based on priority, available bandwidth.

Crossbar fabric: – It provides dedicated, high-bandwidth interconnects between ingress and egress I/O modules

Please refer to Cisco document for more information.