Bridging and Routing
38 Avidia System Configuration and Management User Manual
Bridging and Spanning Tree Protocol
You can configure bridging sessions that forward Ethernet data based on MAC addresses. A
bridge moves information across a network from a source to a destination at the data link layer
(ofan OSI reference model). The information is sent to a physical address on the Ethernet
interface known as a Media Access Control (MAC) address, which is preassigned by a
manufacturer. The MAC forwarding table for an Avidia AMC supports 4096entries. You can
set an aging time interval for the bridging addresses found in the MAC forwarding table. If table
entries are not relearned within the specified time frame (interval), they are deleted.
When bridging, the Avidia system supports the IEEE version 802.1d Spanning Tree Protocol
(STP). STP eliminates loops in a topology by partitioning out redundant links in a connection
between segments. This ensures that there is only one path, or link, between any two points in
a bridging connection. If an active link goes down, Spanning Tree re-enables partitioned links
to create a new loop-free topology, if possible.
Bridging and STP are system-wide functions. When you enable bridging, it is available to any
session set up over a ATM PVC in the system. You can either enable or disable STP when
bridging is enabled. Bridging must be enabled, h owever, to use STP.
Routing
Routing sessions route Ethernet-encapsulated IP datagrams based on IP addresses. A routing
session moves information across a network from a source to a destination at the network layer
(of an OSI reference model). IP routers make forward or filter decisions based on the
network-layer IP address instead of the MAC hardware address.
Routing Protocols. Use Routing Information Protocol (RIP) to automatically identify the
route from the origin of the session to the destination. You can specify the version of RIP that
provides routers information to update their routing tables automatically (for example,
information on how many hops between destinations). The version of RIP you select for the
session must match the version supported by the entire connection:
•RIP Version 1 supports broadcast
•RIP Version1 Compatible is RIP Version 2 which supports broadcast
•RIP Version 2 supports multicast, Plain Text Authentication, and Variable Length Subnet
Masking (VLSM)