Cabletron Systems 2000, Руководство по началу работы, Страница: 24 / 92

Chapter 1: Features Overview
24 SmartSwitch Router 2000 Getting Started Guide
• Layer-4 (application) switching
• Security
• Quality of Service (QoS)
• Statistics
• Management
Bridging
The SSR 2000 provides the following types of high-speed bridging:
• Address-based bridging – The SSR 2000 performs this type of bridging by looking up
the destination address in an L2 lookup table on the expansion module that receives
the bridge packet from the network. The L2 lookup table indicates the exit port(s) for
the bridged packet. If the packet is addressed to the SSR 2000’s own MAC address, the
packet is routed rather than bridged.
• Flow-based bridging – The SSR 2000 performs this type of bridging by looking up an
entry in the L2 lookup table containing both the source and destination addresses of
the bridge packet.
Your choice of bridging method does not affect SSR 2000 performance. However, address-
based bridging is more efficient because it requires fewer table entries while flow-based
bridging provides tighter management and control over bridged traffic.
The SSR 2000 ports perform address-based bridging by default, but can be configured to
perform flow-based bridging instead of address-based bridging on a per-port basis. A
port cannot be configured to perform both types of bridging at the same time.
Port and Protocol VLANs
The SSR 2000 supports the following types of Virtual LANs (VLANs):
• Port-based VLANs – A port-based VLAN is a set of ports that comprises a Layer-2
broadcast domain. The SSR 2000 confines MAC-layer broadcasts to the ports in the
VLAN on which the broadcast originates. SSR 2000 ports outside the VLAN do not
receive the broadcast.
• Protocol-based VLANs – A protocol-based VLAN is a named set of ports that
comprises an IP or IPX broadcast domain. The SSR 2000 confines IP or IPX broadcasts
to the ports within the IP or IPX based VLAN. Protocol-based VLANs sometimes are
called subnet VLANs or Layer-3 VLANs.
You can include the same port in more than one VLAN, even in both port-based and
protocol-based VLANs. Moreover, you can define VLANs that span across multiple
SSR 2000s. To simplify VLAN administration, the SSR 2000 supports 802.1q trunk ports,