To solve problems with DHCP processing, BNG has the following fastdpi.conf settings:

✔ bras_loglevel (number) - sets the logging level into /var/log/dpi/fastdpi_bras.log file:

• 3 - Error
• 4 - Warning
• 5 - Info
• 7 - Trace

The higher the logging level, the more detailed the log. By default, the log level is 5, at which only warnings and errors are displayed in fastdpi_bras.log. Logging level 7 (Trace) will create a detailed log with all DHCP packets, which is very useful when implementing BNG.

✔ bras_log - specifies the full name of the DHCP log file, default value:

bras_log=/var/log/dpi/fastdpi_bras.log

This parameter cannot be changed on-the-fly, SSG restart is required.

✔ bras_dhcp_trace_mac - [SSG 8.1+] specifies the client MAC address for tracing DHCP packets. All DHCP traffic for a given MAC address will be written to the pcap file. Example:

bras_dhcp_trace_mac=a0:b1:c2:d3:00:0a

Only one MAC address can be set on DHCP tracing at a time. pcap file is created in /var/dump/dpi directory. Other pcap recording parameters can also be enabled - all traced packets are written to one pcap file.

This parameter was introduced to solve problems with a specific subscriber equipment: if the client device does not receive an IP-address for some reason, you can put the MAC address of this device on the trace and see what DHCP-packets come to BNG and what DHCP-responses it sends back.