Subject: [SAM] about labelcast

From: zhigang sun <[email-masked]>
Date: Wed, 27 Apr 2011 23:53:28 +0800

Hello all,

I think labelcast can solve two problems that RTP/UDP and IP multicast can
not.

First, In network measurement

Network tomography using RTCP feedback is very useful to deduce the fault or
congested switch node in the network. But its deduce result can not be
verified using the in network measurement which is very important for
network operator. Recent research shows that with more and more power on
routers, in network measure will be a trend. But how to identify streaming
packets or a single IPTV flow in the network? when steaming data is carried
by RTP/UDP, it is not easy to be classified, unless 5-tuple matching is
used. Labelcast, works as a transport layer protocol, can be easily
identified by switch node with its protocol ID in IP header and a flow can
be identified by short label.

UDP can not provide useful information, such as sequence number and time
stamp for in network measurement and fault detection. RTP also has rich
information for quality management, but it is not design for in network
measurement.

Second, Path control

Labelcast use label to control data distribution path. Unlike IP multicast,
labelcast leave a policy interface to network operator to control the path
just like openflow. Based on measurement result or other policies(such
security, traffic engineering etc.), operator can adjust data distribution
path at flow level. I think label-based forwarding can be the supplement of
IP multicast in IPTV networks.

I agree with Dr. wanghui that gateway is a good way making labelcast
transparent to applications. The only thing gateway should do is replace udp
header with labelcast header at the source and replace udp header back at
destination side. Getway can be implemented at host or first/last hop switch
node.

We investigated our local IPTV operator recently and we found that they
almost has no ways to monitoring and control their IPTV flows under current
technologies because network operator can not provide a interface to them. A
paper (about Junos SDK at presto'09)  from juniper provide an novel method
for IPTV qoe monitoring. So to support in network measure, labelcast is one
of the solutions and we are doing this in our lab on routers.

Best Regards

Sun zhigang

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