Fault Tolerant Placement of Stateful VNFs and Dynamic Fault Recovery in Cloud Networks
2019
Traditional network functions such as firewalls and Intrusion Detection Systems (IDS) are implemented in
costly dedicated hardware, making the networks expensive to manage and inflexible to changes. Network
function virtualization enables flexible and inexpensive operation of network functions, by implementing
virtual network functions (VNFs) as software in virtual machines (VMs) that run in commodity servers.
However, VNFs are vulnerable to various faults such as software and hardware failures. Without efficient
and effective fault tolerant mechanisms, the benefits of deploying VNFs in networks can be traded-off. In
this paper, we investigate the problem of fault tolerant VNF placement in cloud networks, by proactively
deploying VNFs in stand-by VM instances when necessary. It is challenging because VNFs are usually stateful.
This means that stand-by instances require continuous state updates from active instances during their
operation, and the fault tolerant methods need to carefully handle such states. Specifically, the placement of
active/stand-by VNF instances, the request routing paths to active instances, and state transfer paths to
stand-by instances need to be jointly considered. To tackle this challenge, we devise an efficient heuristic
algorithm for the fault tolerant VNF placement. We also propose two bicriteria approximation algorithms
with provable approximation ratios for the problem without compute or bandwidth constraints. We then
consider the dynamic fault recovery problem given that some placed active instances of VNFs may go faulty,
for which we propose an approximation algorithm that dynamically switches traffic processing from faulty
VNFs to stand-by instances. Simulations with realistic settings show that our algorithms can significantly
improve the request admission rate compared to conventional approaches. We finally evaluate the performance
of the proposed algorithm for the dynamic fault recovery problem in a real test-bed consisting of both
physical and virtual switches, and results demonstrate that our algorithms have potentials of being applied
in real scenarios.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
0
References
1
Citations
NaN
KQI