Participation in Mantra
Importance of cooperation from the community:
- Most monitoring data that Mantra uses is collected by
capturing various state tables from multicast routers.
Mantra in fact relates a snapshot of the multicast
infrastructure from the point of view of the routers
Mantra collects from. The proximity of the results from
Mantra to that of the global view of the multicast
infrastructure relies on the diversity of the set of routers
from which data is collected, that is, the
differences in their topological and geographical
locations, multicast routing protocols,
amount and type of traffic they generate, etc.
The inherent nature of multicast prohibits derivation of a
global picture via capturing the state information from just
a few routers. Interdomain protocols such as MBGP and sparse mode
protocols such as PIM-SM further hinder the generation of a
global snapshot without monitoring information from multiple
What kind of participation would help:
- Sites willing to participate in Mantra monitoring
can best help the effort by regulrarly providing routing tables from
their local multicast routers to the central Mantra site.
Currently, the tables are captured regularly via expect scripts
to the routers, which requires appropriate access.
Eventually we want to support access via SNMP,
although at this time not all the
protocols have corresponding MIB support.
- Many route tables, e.g., MBGP, DVMRP, MSDP,
depict global multicast state; there is generally no problem
in sharing suchinformation. On the other hand, some information, e.g.,
statistics about the data flow, intranet activities,
might be too sensitive for some participating sites to share.
In the latter case, sites may choose to filter such information
before passing it to us or may not give us access to it at
all. Although the more information provided,
the greater the contribution toward efficient monitoring;
even partial information can be of considerable significance.
- In any case, irrespective of the sensitivity of the
information, almost all
results displayed on the Mantra pages are the result of aggregation
of data collected from multiple sources. Consequently, data
from individual routers are camouflaged by the aggregate
Access to routers:
As mentioned above, until we have SNMP support,
data collection currently requires read-only access to the router.
Participating sites can
either give us read-access to the relevant routers
or they can collect data locally and transfer it to
the central Mantra site.
The former method allows Mantra to do better
error checking, more accurate estimation of time values
and better aggregation of information from multiple
routers, but does require (read-only) access that might
ISPs uncomfortable. The latter method prevents this
security issue, and further gives the site the opportunity
to filter out sensitive information if desired.
Why should sites invest resources in a global monitoring effort?:
- In contrast to unicast routing, debugging multicast routing
relies extensively on cognizance of the global state of
multicast. Participation in a global monitoring effort by
multiple sites will not only help improve the accuracy of the
*global* view but will also provide participating sites
with mechanisms to easily compare their
performance/problems with those of the global multicast
- All the graphs on Mantra's main pages reflect the results
from aggregated data. However, similar results for
individual routers are also available in the section
Routers that we Monitor.
Currently, results from all the routers are
world-accessible, but if necessary/desirable results from
different routers could be made individually password protected.