The biggest advantage of Gigabit Ethernet is its compatibility with existing Ethernet networks. Like 100Mbps Ethernet, Gigabit Ethernet uses the same frame format and frame size as 10Mbps Ethernet, and the same CSMA/CD protocol. It is gradually taking a major role in the campus network backbone.
As a feature of campus network applications, most applications are less sensitive to latency and bandwidth, and can automatically recognize changes in latency and dynamically adapt to the bandwidth provided by TCP/IP through the TCP/IP "slow-start" mechanism, and some applications require real-time service delivery support and QoS service guarantees. This part of the application accounted for a small proportion, with the accelerated modernization of teaching methods, the gradual popularization of multimedia courseware production tools, multimedia courseware gradually rich, the proportion is expected to gradually increase. IP network transmission of real-time services, the main bottleneck is the router software to achieve the routing identification, computation and packet forwarding, due to the slow speed of routing identification, data forwarding, delay and delay jitter, can not guarantee the quality of service (QoS), the quality of service (QoS) is not guaranteed. guarantee quality of service (QoS). Since the second half of 1997, some companies have introduced new wire-speed routing switches that use hardware specialized circuits (ASICs) for route identification, computation and forwarding. The structure of these wire-speed routing switches is similar to that of L2 switches, with both L3 router packet-forwarding and L2 switching functions, and some vendors have also added some L4 application-layer functions to them.
To provide QoS on a packet-switched IP network, services must be categorized and classified as a service (CoS). Equipment manufacturers generally use congestion management to ensure network performance and provide the bandwidth required for some specialized services. One approach is to avoid network congestion by using RED (Random Early Loss) to detect and intelligently identify transient spikes in traffic, distinguishing them from true network congestion. The class of service (802.1P) is identified by identifying the IPv4 class-of-service (TOS) from the IP packet header, prioritizing that data flow, and based on some queue prioritization algorithm in order to ensure QoS capability. Policies can also be defined using Access Control Lists (ACLs) to prioritize data flows. As technology advances, it is foreseeable that QoS capabilities on high-speed IP networks will reach similar levels on FR/ATM networks.
Based on analyzing and comparing the performance, price, and service of a variety of L2/L3/L4 wire-speed routing switches in the market, we chose 11 Cajun P550R routing switches*** from Lucent as the backbone switches of the campus network. Its main technical and performance indicators are:
Backplane capacity 45.76 Gbps
Switching throughput capacity 22.88 Gbps
Layer 2 switching capacity 33,000,000 pps
Layer 3 switching capacity 18,000,000 pps
Multiple L2/L3 interface modules
Redundant Fans, Power Supplies
OpenTrunk/VLAN Interoperability
CoS/QoS/RSVP Support
In the network design, the backbone switches are interconnected to each other via Gigabit Ethernet. All switches are configured with an L3 switching engine that implements a distributed routing policy that reduces the pressure on the center switch for L3 route resolution, packet forwarding, and controlling the extent of the broadcast domain. The network design and equipment configuration carefully considered the physical and logical redundancy of equipment and lines and routes, firewall settings and security policies for the server farm in the network center.