Enterasys Networks VH-8G-L3 ユーザーズマニュアル

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The VH-8G-L3 can be thought of as eight Gigabit Ethernet 
Layer 2 switching domains with a wire-speed router between 
each domain. It can be deployed in a network between a 
traditional router and the intranetwork. The traditional router 
and its associated WAN interface would then handle routing 
between the intranetwork and the WAN (the Internet, for 
example) while the Layer 3 switch would handle routing 
within the LAN (between the Fast Ethernet Layer 2 
domains). 
The VH-8G-L3 can also replace key traditional routers for 
data centers and server farms, routing between these 
locations and the rest of the network, and providing 8 ports 
of Layer 2 switching performance combined with wire-speed 
routing. 
The Functions of a Layer 3 Switch 
Traditional routers, once the core components of large 
networks, became an obstacle to the migration toward next-
generation networks. Attempts to make software-based 
routers forward packets more quickly were inadequate.   
A layer 3 switch does everything to a packet that a traditional 
router does: 
•  Determines forwarding path based on Layer 3 
information 
•  Validates the integrity of the Layer 3 header via 
checksum 
•  Verifies packet expiration and updates accordingly 
•  Processes and responds to any optional information 
•  Updates forwarding statistics in the Management 
Information Base 
•  Applies security controls 
A Layer 3 switch can be placed anywhere within a network 
core or backbone, easily and cost-effectively replacing the