Summary:
This paper introduces a new scalable application layer multicast, NICE, which is based on a hierarchical cluster-based overlay network. The target application of this architecture is what authors call data stream applications which are applications with large multicast group size and low data rates.
The proposed architecture delicately groups the nodes into clusters at difference hierarchical levels such that cluster leaders are also member of clusters at upper levels while every nodes still exist at level 0. Every cluster leader is chosen carefully to be at the center of corresponding cluster (distance metric is delay) and this is crucial in achieving a good stretch metric (low latency). A pleasant feature of this structure is that as long as nothing is changing, the control overhead can be upper bounded while achieving good stress and stretch metrics as well.
The major operations which NICE further need to support are further detailed out: the join operation, cluster maintenance and host departure/leader selection operations. Since a new host needs to be precisely directed to the closest cluster, this operation can take a long time and temporary service needs to be sdupported from upper level cluster leaders. The host/leader separation was also detailed out as well. The comparisons are done mainly with Narada app-layer multicast system both through simulations and experiments.
Critique:
I consider the main contribution of this paper to be the incredibly low control overhead of NICE compared to older architecture Naradia which had O(N^2) control overhead. This will be a significant factor in larger group sizes. One main concern with the NICE architecture can be the slowness of join operations and the robustness against multi high level cluster-head failures. It could have been interesting if there were some results showing the effect of nodes failing at different high levels together. Nevertheless I found their simulations and experiments a very detailed and appropriate one.
This paper introduces a new scalable application layer multicast, NICE, which is based on a hierarchical cluster-based overlay network. The target application of this architecture is what authors call data stream applications which are applications with large multicast group size and low data rates.
The proposed architecture delicately groups the nodes into clusters at difference hierarchical levels such that cluster leaders are also member of clusters at upper levels while every nodes still exist at level 0. Every cluster leader is chosen carefully to be at the center of corresponding cluster (distance metric is delay) and this is crucial in achieving a good stretch metric (low latency). A pleasant feature of this structure is that as long as nothing is changing, the control overhead can be upper bounded while achieving good stress and stretch metrics as well.
The major operations which NICE further need to support are further detailed out: the join operation, cluster maintenance and host departure/leader selection operations. Since a new host needs to be precisely directed to the closest cluster, this operation can take a long time and temporary service needs to be sdupported from upper level cluster leaders. The host/leader separation was also detailed out as well. The comparisons are done mainly with Narada app-layer multicast system both through simulations and experiments.
Critique:
I consider the main contribution of this paper to be the incredibly low control overhead of NICE compared to older architecture Naradia which had O(N^2) control overhead. This will be a significant factor in larger group sizes. One main concern with the NICE architecture can be the slowness of join operations and the robustness against multi high level cluster-head failures. It could have been interesting if there were some results showing the effect of nodes failing at different high levels together. Nevertheless I found their simulations and experiments a very detailed and appropriate one.
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