Generally speaking, to judge the quality of the switch from the overall structure, function and function of three aspects. The overall structure refers to the port density of the switch equipment, the maximum speed of the port support and the value of the basic function parameters such as the AC capacity, so that the user can master the positioning and level of the device in general.
The function of the switch, in addition to meeting the basic specification of RFC2544 recommendations, that is, throughput, delay, packet loss rate, in addition to user business and the use of the deepening, but also added a number of rated targets, such as the number of MAC address, routing table capacity (three-tier switch), ACL number, LSP capacity, the number of support VPN. Take the number of MAC addresses as an example. The number of MAC addresses refers to the number of MAC addresses that can be stored in the MAC Address table of the switch, and the more the number of MAC addresses supported, the higher the speed of data forwarding.
function is the most direct target on the common access layer switches, a simple QoS guarantee, peace mechanism, support network management strategy, spanning tree peace talks and VLANs are necessarily not less function, but if careful analysis, in the superficial appearance can also be some of the function of further subdivision, And these subdivision function is to incur the product difference The primary reason, is also the performance product value added main way.
Use-level QoS guarantee in order to provide greater sensitivity to users in practical use, the QoS strategy of the switch must support the prioritization of the rest of the packets, which can be used to identify the priority settings for Mac addresses, VLANs, IP addresses, and ports.
The switch also has the superior congestion control and the flow limit ability, the support DiffServ distinguishes the service, may according to the source/the target MAC/IP intelligence distinguishes the different use flow, satisfies the seasonable multimedia use the demand. Some switches in the current market are also known as QoS guarantees, but in fact only support the rest of the priority settings, for the user's practice to bring a lot of inconvenience.
VLAN support VLAN is virtual local area network, after dividing the LAN into virtual network VLAN segment, can strengthen the network governance and network security, control the need for data transmission, the network task group can break the share of the network in the geographical status limit, and according to the governance function to divide the subnet. Different manufacturers of the switch to the VLAN support can be divided, supporting the number of VLANs are also divided.
Network management function through the network management function can use governance software to govern, equipment switches, such as Web readers, Telnet, SNMP, Rmon and other governance. In every room, the switch vendors supply the management software or the third party management software long-distance management switch.
The ordinary switch satisfies the snmpmibi/mibii computation management function, moreover supports the equipment management, the service quality management, the warning management and so on strategy, but the complex some gigabit exchange time passes through adds the built-in RMON group (Mini-rmon) to support the RMON automatic guarding function.
Link Aggregation link aggregation can make the link between the switch and the switch and the service channel bandwidth is very good scalability, for example, 2, 3, 4 gigabit link binding together, so that the link bandwidth doubled.
The link aggregation skill can complete the different port load balance, also can each other backup, guarantees the link the redundancy. In some gigabit Ethernet switches, up to 4 sets of link aggregations can be supported, with a maximum of 4 ports per group. Spanning tree negotiation and link aggregation can guarantee the redundancy of a network. Set up redundant links in one network and use spanning tree to negotiate the congestion of backup links, which logically does not constitute a loop, and once the fault is present, enable the backup link.
Support VRRP peace talks VRRP (virtual routing redundancy negotiation) is a kind of guarantee network reliability of the processing scheme. During the peace talks, a redundant backup of the tacit Gateway (DefaultGateway) of the terminal IP device on the shared multiple access media is performed, and then a three-tier switch device is down, the backup device will receive the forwarding task in real time, and the user can switch to a bright and advanced network service quality. VRRP peace talks with Cisco's HSRP peace talks have the same, but HSRP is Cisco private.
At present, the mainstream switch manufacturers have been in their products to support the VRRP peace talks, but widespread use still need some time.