Information Technology Reference
In-Depth Information
Configuration of IRB (Continued)
Example 4-6
!
interface ethernet 2
bridge-group 1
no ip address
!
interface ethernet 3
bridge-group 1
no ip address
!
interface bvi 1
ip address 192.168.3.1 255.255.255.0
The
show interface irb
displays information about the IRB interface.
SRB
This section covers SRB explorer frames, SRT, SR/TLB, RSRB, and DLSw Plus (DLSw+).
SRB Operation
IBM developed SRB in the mid-80s as a way to bridge between Token Ring LANs. The IEEE
adopted most of IBM's proposal into the IEEE 802.5 standard. As shown in Figure 4-20, in
SRB, the source determines the route to the destination node by sending an explorer frame to
it. SRB bridges do not keep a MAC table of hosts and do not worry about bridge loops. This is
different to Ethernet transparent bridging where the bridges have the smarts of MAC layer
destinations and determine the path by creating a spanning-tree. SRB networks are limited to
a 7-bridge hop count. (Some implementations can extend to 13 hops.) In SRB, the source node
obtains the knowledge of routes to destinations on the network. This is accomplished using
explorer frames.
SRB Network
Figure 4-20
bridge
Explorer frame path
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