Packet Description Language Module (PDLM)
An external PDLM can be loaded on the router at runtime using the ip nbar pdlm
command
from the global configuration mode, extending and enhancing the classification engine for the many existing and
emerging application protocols in the NBAR list of protocols. PDLMs can also be used to enhance an existing
protocol recognition capability. PDLMs allow NBAR to recognize new protocols without requiring a new Cisco IOS
image or a router reload. The show ip nbar pdlm command displays all currently loaded PDLMs. Example 7-10
shows the current PDLM loaded from flash memory.
Example 7-10. PDLM Loaded
Router# show ip nbar pdlm
The following PDLMs have been loaded:
flash:gnutella.pdlm
flash:kazaa2.pdlm
flash:edonkey.pdlm
Configuring NBAR
Similar to the other techniques discussed earlier in this chapter, NBAR is configured through the MQC
framework. Example 7-11 shows a class-map "myclass" using the NBAR technique to classify peer-to-peer
(P2P) file-sharing network traffic as its matching criterion using the match protocol commands. P2P traffic is
bandwidth intensive, and most networks would like to manage them. The example shows that P2P can be
blocked using the drop command or policed down to the average rate of 8000 bits per second with a normal
burst size of 1000 bytes and an excess burst size of 1000 bytes.
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