Gigabit乙太網路交換器堆疊協定之設計和實作

Abstract

近年來，網路的使用量不斷地以倍數成長，連接到網路的設備也一天一天地增加。因此，交換器不但要滿足用戶高速上網的需求也要滿足連接網路的擴充性。此謂“擴充性”即能藉由堆疊多台交換器整合成為一台“大”交換器以增加埠數。Gigabit乙太網路交換器上之堆疊協定軟體則是基於此一需求而發展的。堆疊協定軟體的應用可使交換器系統達到更高的埠數，集中管理，更加模組化等優點。在本研究中，我們設計和實作了Gigabit乙太網路交換器上之堆疊協定軟體。首先，藉著探討堆疊交換器設計上的一些議題，包括延伸虛擬區域網路（VLAN），跨堆疊系統的Trunking及Mirroring，位址表的同步，系統的設定，及動態的增加或移除交換器設備等。接著根據三種可能的堆疊設定設計我們的堆疊協定。我們的堆疊協定以state-machine的方式設計，我們並且設計了Configuration Discovery Protocol (CDP)，Event Notify Protocol (ENP)，Data Transmit Protocol (DTP)三種協定跑在state-machine中。由實驗的結果，可得知在功能上獨立乙太網路交換器所有的功能在堆疊乙太網路交換器中都仍然能運作正常；而在效能上，堆疊乙太網路交換器也都幾乎和獨立乙太網路交換器相當接近，而達到增加埠數，彈性，擴充性等優點。

Network traffic volumes are accelerating quickly and more and more devices are connected to the network day by day. As a result, switch devices need to meet not only enterprise customers’ high-speed connectivity but also scalability for additional users joining the network. For the scalability, it means more ports can be added by “stacking” additional switches on top of one another with a common external interconnection; in effect, creating one big integrated switch. And stacking software on Gigabit Ethernet Switch is developed based on these requirements to provide many advantages including high port density, centralized management, redundancy, modularity, etc. In this work, we propose our design and implementation of the stacking software on Gigabit Ethernet Switch. We discuss some design issues for the stacking protocol including VLAN membership, trunking and port mirroring across the stacking system, L2 table synchronization, port accessibility, system configuration for the stack, runtime insertion or deletion switch devices and elaborate the stacking protocols for 3 kind of possible system configurations. The stacking software is run using a state machine mechanism and related protocols will be run on related states. For the experimental results, we can see Gigabit Ethernet switch system with the stacking protocol running on it has the same functionality and nearly the same performance with the standalone Gigabit Ethernet switch device to provide high port density, flexibility, and scalability.