About Internet2 and Multicast Connectivity
Contents
What is Internet2 connectivity, and
why does ConferenceXP check for it?
How does the Connectivity
Detector utility work?
Using
Connectivity Detector to troubleshoot multicast problems
Connectivity Detector is a network diagnostic utility that detects whether your computer
is connected to Internet2®.
It also detects whether your computer is connected to a multicast network, which
enables you to participate in ConferenceXP conferences. If your computer is not
connected to a multicast network, you can
start a
two-way conference over unicast, or you can
use ConferenceXP Reflector Service to connect to a multicast network.
What is Internet2 connectivity,
and why does ConferenceXP check for it?
ConferenceXP relies upon a network that is reliable, offers decent performance,
and permits multicast connections between organizations. Although Internet2 and
many private networks, such as wide area networks (WANs), fit these requirements,
this often isn’t the case between organizations connected over the standard Internet.
Multicast has been around for a very long time, but it still suffers from interoperability
problems and general lack of use. A chicken and egg problem exists: networks don’t
bother to enable multicast at their borders because so few applications will take
advantage of it and applications don’t take advantage of the improved scalability
of multicast because most networks don’t enable it. Although modern routers fully
support multicast, they do take some configuration by network administrators, and
it’s easy to configure them incorrectly. For example, if no one ever used TCP/IP,
network administrators wouldn’t perform simple tests like “ping” or “open my favorite
Web site” after each configuration change or firmware upgrade. Eventually, silently,
some configuration setting would change or some firmware bug would be introduced
that prevented TCP/IP for working and no one would notice. This is the state of
multicast today.
While the Internet2 backbone fully supports multicast, it’s been our experience
that at almost every university we’ve worked with, multicast isn’t properly working
on the routers that connect the university to Internet2. We face a lack of knowledge
in network administrators who have never configured multicast before. Even after
we get multicast working, it’s all too frequent that a few weeks or months later
after some firmware update or configuration change, multicast breaks.
To check the status and capability of your Internet2 network connection, try
the Internet2 Detective.
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How does the Connectivity
Detector utility work?
Connectivity Detector checks for Internet2 and multicast connectivity by sending
and receiving multicast IP packets to a known address and looking for responses
from known hosts on Internet2. When you start Connectivity Detector, it sends a
small data packet (a UTF-8 string encapsulated in RTP over UDP; see RFC 1889) once
per second to multicast IP address 233.45.17.171:5004 and a series of control packets
(RTCP SDES, RR, and SR; see RFC 1889) to 233.45.17.171:5005. It looks for similar
signals sent from Internet2, including packets from known hosts.
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Using Connectivity Detector to troubleshoot multicast problems
To troubleshoot multicast problems, you need a diagnostic tool that can detect
multicast problems and report them effectively. The Connectivity Detector utility
helps you determine if your network is working. It displays the detailed technical
information you need to accurately describe the problem to your network administrator.
For example, are you connected to your network? Can you see other sites on the
Internet? If so, provide details about the problem to your network administrator.
In the Connectivity Detector window, you can copy the technical details it
reports into an e-mail message or Web-based reporting system for your network administrator.
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