Top-of-rack switches

Our servers are connected to three different networks – the public network (Internet), a private network, and an out-of-band management network. These networks are fully independent. Both private and public networks are L3 fabrics with two-tier leaf-spine network topology.

Leaf-spine topology

A leaf-spine topology is a data center network architecture that consists of two switching layers — a spine and a leaf. Servers are connected to the lower-tier switches (leaf layer). Every switch in the leaf layer is connected to each of the top-tier switches (spine layer) in a full-mesh topology providing a 3-hop connection between any two servers. The leaf layer aggregates traffic from servers and connects directly into the spine. The spine aggregates traffic from the leaf layer and connects directly into the network core.

L3 fabric with two-tier leaf-spine network topology is vendor-independent, reliable, error-proof, scalable, and suits modern data center environment better than L2-based solutions.

Redundancy

L3 fabric is the only way to achieve true redundancy. Traditional L2 networks are built using the spanning-tree protocol, which utilizes only a single “best path” chosen from all available paths. This means there is an active/standby redundancy. The problem is when something goes wrong, you can’t be sure that the standby path is reliable. Unlike that, L3 fabric is active/active and utilizes all available paths concurrently while remaining stable and avoiding loops within the network.

In Servers.com, each layer – leaf, spine, and core – is redundant. In both – the private and the public networks. Each server is equipped with at least two dual-port NICs. One port on each NIC is used for private network connection, and one is for public. Each port is connected to a different switch, meaning each server has a connection to two public and two private network switches. Every leaf switch is then connected to two spine switches. Each of spine switches is connected to one of two routers. On every public network router, several Tier1 carriers are present. Each private network router has at least two connections to the private network. Thanks to this redundancy on each networking layer, Servers.com customer is protected from:

• Failure of any carrier;

• Failure of any piece of network equipment;

• And even failure of a network interface card on a server.

Leaf/top-of-rack switches

We use top-of-rack leaf switches from one of the leading US-based networking companies. Each leaf switch offers 48 10GBASE-T ports and four 40 GbE QSFP+ ports.

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