1 Introduction
Recently, I was reading "Cloud Data Center Network Technology" and learned the process of enterprise data center network construction. I saw that there are two wiring methods, ToR and EoR. I have never touched it before, so I will summarize it today.
2. Wiring method
ToR: The (Top of Rack) access method is to install an access switch on the top of the server cabinet.
EoR: (End of Row) access switches are centrally installed in a cabinet at the end of a row of cabinets, and are connected to the host/server/minicomputer devices in the equipment cabinet through a permanent link through horizontal cables. EoR pairs of equipment racks require extensive horizontal cabling to the switches.
3. Comparison
Disadvantages of the EOR wiring method: There are many copper cables from the server cabinet to the network cabinet (about 20-40 copper cables), and the farther the copper cables from the server cabinet are from the network cabinet, the longer the wiring distance in the equipment room, the This results in heavy cable management and maintenance workload and poor flexibility.
Disadvantages of TOR cabling: Each server cabinet is limited by the output power of the power supply, and the number of servers that can be deployed is limited, resulting in insufficient utilization of the access ports of the switches in the cabinet. Sharing 1-2 access switches among several server cabinets can solve the problem of insufficient utilization of switch ports, but this method increases the workload of cable management.
From the perspective of network design, the number of VLANs on each access switch in the TOR wiring method is not very large. In network planning, it is necessary to try to avoid a VLAN spanning multiple access switches through the aggregation switch. Therefore, the TOR wiring method is used. In the network topology, the scope of each VLAN will not be too large, and the number of ports included will not be too large. However, for the EOR wiring method, the port density of the access switch is high. When the network is initially designed, there may be VLANs with a large number of ports.
The number of access switches in TOR mode is large, and the number of access switches in EOR mode is small, so the network equipment management and maintenance workload in TOR mode is heavy.
With the sharp increase in user data service requirements, the density of servers in data center computer rooms is getting higher and higher, and new technologies such as virtualization and cloud computing are becoming more and more popular, which greatly increases the network ports corresponding to servers and increases the complexity of management. The convergence of Ethernet (LAN) and fiber storage area network (SAN) is becoming more and more common, which inevitably requires a new network topology to correspond to it. Under the tide of cloud computing, the business scalability of this distributed architecture is extremely strong, and the number of servers required is increasing. For example, the new Apache Hadoop 0.23 supports 6,000 to 10,000 servers in a cluster. The large number of servers requires full use of the cabinet space of the data center. At the same time, the large amount of business data also requires faster and more direct high-performance links to transmit data to network core. Under such a trend, ToR is obviously more applicable. Under the pressure of rapid business expansion, the ToR method can better achieve faster network expansion.
4. References
http://blog.51cto.com/dannyswallow/1731777
http://www.excitingip.com/2802/data-center-network-top-of-rack-tor-vs-end-of-row-eor-design/
http://blog.51cto.com/cteam/674194