Chesapeake NetCraftsmen

I’ve lately been looking at Cisco data center switches. I thought I would compare highlights of the Nexus 5000 and Nexus 7000 switches.

Overview

Cisco has targeted both products for the data center, and grouped them in the Nexus family. However, these are two pretty different products at this time. Although they both use the modular Nexus operating system (they use different modules of it!), the Nexus 5020 is a Layer 2 switch integrating 10GE switching and SAN fabrics, while the Nexus 7010 is a Layer 3 switch.

Nexus 5000

The focus of the Nexus 5000 is to provide high speed Layer 2 on an integrated fabric backplane supporting 10Gb Ethernet switching for LAN, SAN, and cluster traffic. It uses “Data Center Ethernet” to provide Fibre Channel over Ethernet (FCoE) which encapsulates Fibre Channel traffic over a physical Ethernet link. One physical Ethernet cable can carry both a logical Ethernet subinterface and a logical Fibre Channel subinterface.

The Nexus 5000 uses a cut through switching architecture with a 1 Terabits/sec backplane so that forwarding packet starts as soon as enough header info is known. The Nexus 5000 uses Virtual Output Queues (VOQ) on ingress side for every egress port and egress queue, so may provide some buffering as well.

One strength of the Nexus 5000 is that it allows users to consolidate I/O for LAN and SAN traffic by providing native Fibre Channel over Ethernet support. It comes with forty fixed 10 GE/FCoE ports with expansion modules for additional FC or Ethernet ports.

The Nexus 5000 runs Layer 2 components of the Cisco Nexus operating system (NX-OS). On the Nexus 5000, NX-OS provides 10GE switching and Cisco fabric services. For example, NX-OS supports RST or MST on the Ethernet ports (VLANs, trunks, etc), and provides Fibre Channel management including VSANs, zoning, and distributed device alias service. You can configure and manage the most attributes of the Nexus 5000 from the command line interface. As an alternative, you can use the Cisco Fabric Manager for most functions, but you will still need the command line interface to configure most Layer 2 Ethernet capabilities.

Nexus 7000

The current focus of the Nexus 7000 is to provide high density 10Gb Ethernet switching for LAN traffic. (Cisco is planning to provide unified I/O for this switch in the future.)

The Nexus 7010 is a very modular switch - it has dedicated slots for supervisors, and 8 slots for I/O modules. Up to five backplane fabric modules can redundantly interconnect the I/O modules. Although the current fabric modules can provide up to 46Gbps to each I/O module slot, the initial line cards can only use 80 Gbps of the current 230 Gbps backplane. (Cisco states that the fabric will scale to 15 Terabits per second. The fabric modules provide backplane redundancy and are upgradeable and hot swappable.) The Nexus 7000 also uses Virtual Output Queues (VOQ) on ingress side for every egress port and egress queue.

One strength of the Nexus 7000 is that it allows administrators with the Advanced Services license package to configure virtual device contexts (VDCs) that partition a single physical device into multiple logical devices. A VDC runs as a separate logical entity within the physical switch, maintains its own set of running software processes, has its own configuration, and can be managed by a separate administrator. [The Nexus 7000 does NOT support the Catalyst 6500 virtual switching system (VSS) that allows pooling of two Catalyst 6500 switches into one virtual switch.]

The Nexus 7000 runs Layer 2 and Layer 3 components of the modular Cisco Nexus operating system (NX-OS). On the Nexus 7000, NX-OS Enterprise Services license provides 10GE switching and routing services. For example, it supports RST or MST on the Ethernet ports (VLANs, trunks, etc), and allows you to enable routing protocols through features. You can configure and manage the most attributes of the Nexus 7000 from the command line interface that is fairly similar to the Cisco IOS CLI.

The Nexus 7000 is most similar to the Catalyst 6500, except that the Nexus 7000 only supports Ethernet I/O cards at this time but not any service modules.