Powerful features of gigabit backbone switches

Here we mainly aim at gigabit backbone switches and conduct a comprehensive evaluation of their performance in detail. In fact, for general users, what we value is cost effectiveness, rather than pursuing a good performance. Several Gigabit backbone switches provided for test are provided with detailed documentation. Here we first introduced the instructions of Digital China D-Link, which is very detailed. The previous section describes the basic knowledge of layer-2 switching and layer-3 routing, and then describes the functions of vswitches in detail.

In addition, the specification of the vswitch is Chinese, which is also easy for domestic engineers to read. 3Com4900 Provides CD and printed instruction documents, which are also very detailed. In addition, the website of 3Com can also download all related file information of the vswitch. The Thinker3800 switch of the creative company we got provides a CD with a Chinese instruction in detail.

Powerful functions

Our evaluation is mainly to measure the performance of the Gigabit backbone switch. At the same time, we also consider the functions of the switch through configuration and validation tests. Two of the switches we tested are capable of forwarding on the third layer. Digital China D-Link DGS-3308TG is one of them, we set their eight ports to different VLANs, into different subnets to test its performance, quite good. As a fixed and modular switch, it also supports more complex routing protocols such as OSPF.

Another layer-3 switch is 3Com4900. After the software is upgraded, It is a layer-3 or layer-4 switch. We tested its L3 performance. In layer-4 mode, it can identify application streams based on TCP port numbers and assign priority to different application streams. For example, assign a high priority to the packets of an SNMP application to ensure network management is feasible. Set a higher priority for an application whose port number is 80.

In fact, to ensure high network performance, these Gigabit backbone switches that can be managed support restrictions on broadcast storms. At the same time, all the send and test switches support the traffic control protocol of X 3 to ensure that, in the case of congestion, they negotiate with other network devices to reduce the transmission speed of frames and relieve network congestion. For vswitches that support copper interfaces, they also support back-pressure traffic control in Mbit/s half-duplex mode.

More switches provide IEEE 802.1p priority control, 3Com4900 and shenzhou.com-Link's DGS-3308TG company switch provides 4 priority queues for each port, which is the most popular in test-free products. The DGS-3308TG of digital D-Link can also assign priority based on the source and destination addresses of data frames. We found that many switches combine the P priority with the Q setting to provide VLAN service quality control. In fact, in addition to ensuring security, VLANs can also improve network performance by limiting broadcast domains.

All vswitches support VLAN 802.1Q. The digital D-Link DGS-3308TG switch supports up to 2048 VLANs. 802.1Q can be tagged on an Ethernet frame so that a VLAN can span multiple switches and one port of a vswitch belongs to multiple VLANs at the same time. These Gigabit backbone switches support GVRP and GMRP, allowing the host to automatically register to the VLAN and multicast group of the network.

Link aggregation makes the link bandwidth between vswitches and servers very scalable. For example, we can bind two, three, and four Gigabit Links together, multiply the bandwidth of the link. The link aggregation technology can achieve load balancing of different ports, while also ensuring link redundancy. These Gigabit backbone switches support up to four link aggregation groups and each group has up to four ports. Generally, when link aggregation is set, we can see which ports belong to one switching chip. Cross-chip settings are not allowed for half of link aggregation.

Both the Spanning Tree Protocol and link aggregation can ensure the redundancy of a network. Set redundant links in a network and use the Spanning Tree Protocol to block the backup link without forming a loop logically. If a fault occurs, the backup link is enabled. However, the Spanning Tree Protocol takes too long to compute. IEEE is developing a new protocol, which is yuan. The 3Com vswitch has an elastic link setting option. If two links are set as an elastic link group, when one link is disconnected, the Gigabit backbone switch will quickly start working on another link, the efficiency is higher than the spanning tree algorithm. It is said that the switchover can be completed within one second.

More and more people pay attention to the security of networks. vswitches can isolate illegal customers from the network at the underlying layer. All the vswitches that can be managed support the MAC address filtering function. You can also bind the MAC address with a fixed port and the VLAN. The 3Com and Digital China D-Link vswitches also support higher-level access list control.

In the face of more and more multicast applications, network-managed switches support IP multicast. Generally, they support IGMP (InternetGroupManagementProtocol). ge backbone switches can intelligently forward IGMP and multicast data packets, instead of broadcasting these packets to all ports.

IGMP probe IGMPSnooping) enables the Gigabit backbone switch to read IGMP data packets before forwarding data packets to learn which port is a multicast member ). 3Com4900 and digital shenzhoud-Link DGS-3308TG switches support layer-3 switching, with stronger support for IP multicast.