When designing a virtual infrastructure an important bit in the design is the storage infrastructure also called the Storage Area Network (SAN). In a SAN based on iSCSI we often use Cisco 3750 switches, but when you are going to select the right Cisco 3750 for the job the fun starts. You will be dazzled by the amount of different product numbers and will be busy deciphering the product code.

The product code for a Cisco 3750 switch is build up like this:

WS-C3750a-xxbc-dee

WS stands for Switch C stands for Catalyst series 3750 stands for the 3750 product line

a >> blank, G, E blank = classic 3750 switch, 6.5 or 13.1 mpps forwarding rate G = all ports are gigabit, 35 or 38 mpps forwarding rate E = enterprise line, 65.5 or 101.2 mpps forwarding rate

xx >> 12, 16, 24, 48 12 = 12 Ethernet ports 16 = 16 Ethernet ports 24 = 24 Ethernet ports 48 = 48 Ethernet ports

b >> T, P, F, D, W T = Ethernet ports P = Power over Ethernet

F = 100BASE-FX fiber D = 10 Gigabit Ethernet XENPAK port W = Wireless

c >> S S = 2 or 4 Small Form-Factor Pluggable (SFP) uplinks

d >> E, S S = Standard IP Base image (IPB) E = Enhanced IP Services (IPS)

ee >> 1U, D, 25, 50 1U = 1U Rack Height D = DC Power Supply 25 = 25 Access points for wireless supported 50 = 50 Access points for wireless supported

The Cisco 3750 product line consists of nonblocking switches which support Jumbo frames, flow control and are easy to build up and expand a pay as you grow infrastructure. By using the Cisco StackWise technology you create a single stack which operates as 1 single big virtual switch, is easy to manage through 1 IP address and can grow and shrink per unit. For power efficiency you can make use of the Cisco EnergyWise Technology. Availability can be obtained by evenly distributing the connections over the several switches in the same stack so when building a switch stack that should be high available use minimal 2 units.

Some techniques explained:

Nonblocking switch A nonblocking minimal spanning switch is a device that can connect N inputs to N outputs in any combination. The most familiar use of switches of this type is in a telephone exchange. The term “non-blocking” means that if it is not defective, it can always make the connection. The term “minimal” means that it has the fewest possible components, and therefore the minimal expense. Source: http://en.wikipedia.org/wiki/Nonblocking_minimal_spanning_switch

Cisco Stackwise technology Cisco StackWise technology is a stacking architecture optimized for Gigabit Ethernet with 32-Gbps interconnect throughput. Cisco StackWise technology unites up to nine individual Cisco Catalyst 3750 switches into a single logical unit, using special stack interconnect cables and stacking software. The stack behaves as a single switching unit that is managed by a master switch elected from one of the member switches. The master switch automatically creates and updates all the switching and optional routing tables. A working stack can accept new members or delete old ones without service interruption.

Cisco Cluster Management Suite The Cisco Cluster Management Suite (CMS) is a Web-based software that is embedded in Cisco Switches. Through Cisco Switch Clustering technology, users can access Cisco CMS with any standard Web browser to manage up to 16 switches at once, regardless of their geographic proximity. Administrators also have the option of using a single IP address for the entire cluster if desired.

Cisco EnergyWise Technology Cisco EnergyWise enables companies to measure the power consumption of network infrastructure and network-attached devices and manage power consumption with specific policies, reducing power consumption to realize increased cost savings, potentially affecting any powered device. Cisco EnergyWise extends the network as a platform for the power control plane for gathering, managing, and reducing power consumption of all devices, resulting in company wide optimized power delivery and reduced energy costs.

I have been asked several questions about which type and product number to order for different customers, so hereby a summary:

Q: What is the difference between a Cisco Catalyst 3750 and a Cisco Catalyst 3750G switch? A: The G in the product code stands for gigabit ports. The Cisco 3750 also known as ‘classic’ contains ethernet ports with a speed of 10/100, where the Cisco 3750G contains all gigabit ports with a speed of 10/100/1000.

Q: What is the difference between a Cisco Catalyst 3750(G) and a Cisco Catalyst 3750E switch? A: The Cisco 3750E is the enterprise class in the Cisco 3750 switch line. The enterprise class line has a much bigger and faster backplane which can transport with 65 mpps or 102 mpps forwarding rate.

Q: Does the IP Base Image set support Jumbo frames? A: Yes it does on layer 2. Configurable maximum transmission unit (MTU) of up to 9000 bytes, with a maximum Ethernet frame size of 9018 bytes (jumbo frames) for bridging on Gigabit Ethernet ports, and up to 1546 bytes for bridging and routing on Fast Ethernet ports. All Cisco Catalyst 3750-E Series switch models also support jumbo frames for Layer 3.

Q: Can I mix different Cisco 3750 switches in a stack? A: Yes, you can Mix-and-Match switch types in a stack. Stacks can be created with any combination of Cisco Catalyst 3750 and Cisco Catalyst 3750-E switches. Customers who need a mixture of 10/100 and 10/100/1000 ports, PoE, and wiring-closet aggregation capability can incrementally develop the access environment, paying only for what they need. When uplink capacity needs to be increased, you can easily upgrade your bandwidth by adding a 10 Gigabit Ethernet version to the stack and upgrade your Gigabit Ethernet links with 10 Gigabit Ethernet on the existing fiber.

Q: Which Cisco software image should I choose? A: There are two types of image you can choose from the IP Base or the IP Services Image. The Cisco Catalyst 3750 Series is available with either the IP Base (IPB) or the IP Services (IPS) image.

The IP Base image feature set includes advanced quality of service (QoS), rate-limiting, access control lists (ACLs), static routing, Routing Information Protocol (RIP) and EIGRP stub routing, capabilities.

The IP Services image provides a richer set of enterprise-class features, including advanced hardware-based IPv6 and multicast routing.

Cisco Catalyst 3750 Series Switches Data Sheet Cisco Catalyst 3750 Series Switches Quick Look comparison sheet for the Cisco 3750 and 3750G Cisco Catalyst 3750-E Series Switches Data Sheet