Enterasys Networks VH-8G-L3 - Manual (Page 17)

7 9033705-01
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