Basic Data Center Design

Basic Data Center Design

Juniper's "3-2-1" data center network architecture collapses multiple switching tiers leading to a new simplified data center architecture design that requires fewer devices and interconnections. Juniper Networks helps enterprises simplify their data center network architecture by collapsing it into two tiers with Virtual Chassis fabric technology, and finally, to one tier with QFabric. By leveraging a common operating system, an open network automation platform, and an industry-leading product and services portfolio, we help to reduce the total cost of ownership and provide performance, scale, and agility.

Two-Tier Data Center Reference Design — Focus on the Access Tier

The slide illustrates a two-tier data center reference design. The major architectural elements of the design are the consolidated core and aggregation tiers, services, the access tier, and storage and servers. Management of all data center devices covers all areas

Data Center Access Tier

As its name implies, the access tier is the point of entry into the network for servers, storage, and computing devices. It is basically where and how users are connected to the network, and is the foundation and building block of the entire data center network, because the purpose of the data center network is to connect all of the user devices. The access tier truly is the fundamental building block of the data center network and affects network size.

The access tier provides connectivity to all shared enterprise servers, applications, storage devices, and any IP or office automation devices required in the data center facility

You can configure access switches to use Layer 2 protocols, Layer 3 routing protocols, or both

Layer 2 at the Access Tier

An important aspect you need to consider is access tier uplink connection. One of the options is to keep Layer 2 access. In this configuration, Layer 3 termination of traffic occurs at the core-aggregation tier, enabling the virtual LAN (VLAN) to span across multiple access devices.

Layer 2 at the Access Tier — Challenges

Spanning of the VLAN creates the challenge of a larger spanning tree domain, increasing the fault containment area. Also, this approach results in increased network convergence time.

Architecture and Protocols Deployed

The access tier uses a Virtual Chassis with an 802.1Q trunk configuration. The 802.1Q trunk can run across the LAG uplink for link redundancy. You can group multiple physical switch ports into a logical point-to-point link, known as a LAG. A LAG provides increased bandwidth and link redundancy. If one link in the LAG fails, the system automatically redirects traffic across the remaining links. You can include up to eight ports within a LAG in a Virtual Chassis configuration. Ports can be distributed across the fixed or uplink ports of any members. A Virtual Chassis can support up to 64 LAGs.

Because it is a Layer 2 interconnect, a Redundant Trunk Group (RTG) or the Spanning Tree Protocol (STP) configuration is required for loop prevention.