Network bridges are used to connect separate network segments. When connected by a bridge, the attached network segments communicate as if they were a single network segment. Bridging is implemented at the datalink layer (L2) of the networking stack to connect subnetworks together.
Using a bridge configuration simplifies the administration of the various nodes in the network by connecting them to a single network. By connecting these segments through a bridge, all the nodes share a single broadcast network. Thus, each node can reach the other nodes by using network protocols such as IP rather than by using routers to forward traffic across network segments. If you do not use a bridge, you must configure IP routing to permit the forwarding of IP traffic between nodes.
To forward packets to their destinations, bridges must listen in promiscuous mode on every link that is attached to the bridge. Listening in promiscuous mode causes bridges to become vulnerable to the occurrences of forwarding loops, in which packets circle forever at full line rate. To prevent this, bridging uses the Spanning Tree Protocol (STP) to prevent network loops that would render the subnetworks unusable. In addition to STP, Oracle Solaris 11 supports the Transparent Interconnect of Lots of Links (TRILL) protocol.
Unlike STP and RSTP, TRILL does not shut down physical links to prevent loops. Instead, TRILL computes the shortest-path information for each TRILL node in the network and uses that information to forward packets to individual destinations. As a result, TRILL enables the system to leave all links in use at all times.
Data Center Bridging (DCB) is a set of features that enhance traditional Ethernet networks’ abilities to manage traffic especially in environments where network traffic volume and transmission rates are high. DCB features address fibre channel’s sensitivity to packet loss while traversing the Ethernet network. It enables peers to distinguish traffic based on priorities. Support for enhanced transmission selection (ETS) based on IEEE 802.1Qaz has been added to the DCB functionality introduced in Oracle Solaris 11 11/11. This will provide guaranteed bandwidth and lossless Ethernet transport for converged network environments where storage protocols share the same fabric as regular network traffic.
EVB is an IEEE standard that defines new protocols and mechanisms for exchanging information about virtual links between hosts/stations and a switch/bridge. With EVB, more information about virtual link configurations can be advertised on the network beyond, for example, bandwidth share or priority definitions for physical links that DCB features provide. In general, EVB can be used to enable reflective relay on the external bridge port and automate virtual port configuration on the bridge. Support for the EVB Virtual Station Interface (VSI) Discovery and Configuration Protocol (VDP) and the Edge Control Protocol (ECP) are new in Oracle Solaris 11.1 release. Using EVB, properties (such as the bandwidth limit) of the Oracle Solaris Virtual NIC (VNIC) can be exchanged with the switch so that the switch can be configured accordingly for the VNIC. The standard is defined in the IEEE 802.1Qbg specification.
With the introduction of network virtualization, inter-VM traffic is sent through an internal software switch without being sent through the physical network infrastructure. This process aids organizations that have networking policies that require all network traffic to be routed through an external network so that access control lists (ACL), packet monitoring, and so on can be configured on the external switch. In this release, you can enable reflective relay to ensure that this inter-VM traffic is also subjected to these same policies.
Configuring a Network Bridge
The example below shows you how to create, display, and remove a network bridge.
1. Create a Bridge:
# dladm create-bridge -l net0 -l net3 tonowhere
2. Display Bridge:
# dladm show-bridge BRIDGE PROTECT ADDRESS PRIORITY DESROOT tonowhere stp 32768/8:0:27:15:2:19 32768 32768/8:0:27:15:2:19
# dladm show-bridge -l tonowhere LINK STATE UPTIME DESROOT net0 forwarding 90 32768/8:0:27:15:2:19 net3 discarding 90 32768/8:0:27:15:2:19
3. Removing Bridge:
# dladm remove-bridge -l net0 -l net3 tonowhere # dladm delete-bridge tonowhere