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CCIE Routing and Switching Exam Certification Guide

Chapter Description

Prepare for the CCIE Routing and Switching Exam with this excellent study resource. Review such topics as MAC address format, VLAN trunking, transparent bridge functions, and much more.


CRB enables the router to both route and bridge the same protocol on separate interfaces. With IRB, a protocol can be routed between routed interfaces, bridged interfaces, or different bridge groups.

The access list numbers for MAC address filters are from 700 to 799. The access list for EtherType filters are from 200 to 299.

Table 4-18 Methods for Using SRBs

Bridge Type


Source route bridging (SRB)

The source determines the route to use to reach the destination node before sending an information frame to it. The bridge does not store MAC addresses. Limited to 7 bridge hops; explorer frames used by stations.

Source route transparent bridging (SRT)

SRT bridges can forward traffic from both transparent and source-route end nodes and form a common spanning tree with transparent bridges.

Source-route translational bridging (SR/TLB)

Bridge between SRB and transparently bridged networks. Look at MTU, reorder bits, convert frames.

Remote source route bridging (RSRB)

Permits the bridging of token rings located on separate routers across non-Token Ring media. The virtual ring spans the peer routers.

Data-link switching (DLSw)

DLSw serves as a replacement of SRB and serves SNA data-link connections (DLC) and NetBIOS traffic. Supports RIF terminations.