CHAPTER
15-1
Ethernet Card Software Feature and Configuration Guide, R7.2
January 2009
15
Configuring the Switching Database Manager
This chapter describes the switching database manager (SDM) features built into the ML-Series card and
contains the following major sections:
Understanding the SDM, page 15-1
Understanding SDM Regions, page 15-1
Configuring SDM, page 15-2
Monitoring and Verifying SDM, page 15-3

Understanding the SDM

ML-Series cards use the forwarding engine and ternary content-addressable memory (TCAM) to
implement high-speed forwarding. The high-speed forwarding information is maintained in TCAM. The
SDM is the software subsystem that manages the switching information maintained in TCAM.
SDM organizes the switching information in TCAM into application-specific regions and configures the
size of these application regions. SDM enables exact-match and longest-match address searches, which
result in high-speed forwarding. SDM manages TCAM space by partition ing application-specific
switching information into multiple regions.
TCAM identifies a location index associated with each packet forwarded and conveys it to the
forwarding engine. The forwarding engine uses this location index to derive information assoc iated with
each forwarded packet.

Understanding SDM Regions

SDM partitions multiple application-specific regions and interacts with the individual application
control layers to store switching information. The regions share the total available space. SDM consists
of the following types of regions:
Exact-match region—The exact-match region consists of entries for multiple application regions
such as IP adjacencies.
Longest-match region—Each longest-match region consists of multiple buckets or groups of
Layer 3 address entries organized in decreasing order by mask length. All entries within a bucket
share the same mask value and key size. The buckets can change their size dynamically by
borrowing address entries from neighboring buckets. Although the size of the w hole application
region is fixed, you can reconfigure it.