Configuring DVMRP
Configuring DVMRP
page 5-12
OmniSwitch AOS Release 7 Advanced Routing Configuration Guide
March 2011
Automatic Loading and Enabling of DVMRP Following a System Boot
If
any
DVMRP command is saved to the
boot.cfg
file in the post-boot running directory, DVMRP will be
loaded into memory automatically. The post-boot running directory refers to the directory the switch will
use as its running directory following the next system boot (i.e., Working or Certified). If the command
syntax
ip dvmrp admin-state enable
is saved to the
boot.cfg
file in the post-boot running directory,
DVMRP will be automatically loaded into memory
and
globally enabled following the next system boot.
For detailed information on the Working and Certified directories and how they are used during system
boot, see the “CMM Directory Management” chapter in the
OmniSwitch AOS Release 7 Switch Manage-
ment Guide
.
Neighbor Communications
Probe messages are sent out periodically on all the DVMRP interfaces. However, only on the non-tunnel
interfaces are they sent out to the multicast group address 224.0.0.4.
Note.
Older versions of DVMRP use Route Report messages to perform neighbor discovery rather than
the Probe messages used in DVMRP Version 3.
The
ip dvmrp neighbor-interval
command enables you to configure the interval, in seconds, at which
Probe messages are transmitted. For example, to configure the Probe interval to ten seconds, enter the
following command:
-> ip dvmrp neighbor-interval 10
The
ip dvmrp neighbor-timeout
command enables you to configure the number of seconds that the
DVMRP router will wait for activity from a neighboring DVMRP router before assuming the neighbor is
down. For example, to configure the neighbor timeout period to 35 seconds, enter the following command:
-> ip dvmrp neighbor-timeout 35
When the neighbor timeout expires and it is assumed that the neighbor is down, the following occurs:
•
All routes learned from the neighbor are immediately placed in hold down.
•
If the neighbor is considered to be the designated forwarder for any of the routes it is advertising, a new
designated forwarder for each source network is selected.
•
If the neighbor is upstream, any cache entries based upon this upstream neighbor are flushed.
•
Any outstanding grafts awaiting acknowledgments from this neighbor are flushed.
•
All downstream dependencies received from this neighbor are removed.
Set the default values for
ip dvmrp neighbor-interval
and
ip dvmrp neighbor-timeout
. This enables
early detection of a lost neighbor yet provides tolerance for busy multicast routers. Both of these values
must be coordinated between all DVMRP routers on a physical network segment.
Note.
Current global DVMRP parameter values—including the
ip dvmrp neighbor-interval
value and
the
ip dvmrp neighbor-timeout
value—can be viewed via the
show ip dvmrp
command. The DVMRP
neighbor table can be viewed via the
show ip dvmrp neighbor
command.
