Talk from the inaugural workshop of the Swiss SDN working group in October 2013. In the context of a green-field "cloud" infrastructure build, the talk looks at three areas where "SDN" techniques seem useful: To scale the internal network fabric across many racks; to realize a cost-effective high-bandwidth uplink connection to the Internet; to support "virtual private cloud" services using tunneling.

1. Building Cloud
Where SDN Could Help
SDN Workshop, Zurich, 30.October 2013
Simon Leinen
simon.leinen@switch.ch

2. SWITCH “Cloud” Experience (so far)
• Built ~10-node Ceph+OpenStack cluster
BCC – “building cloud competence”
• Services:
– VMs for various researchers and internal testers
– File synchronization server for ~500 end users
in “Cloud Shared Storage” usability tests –
ownCloud vs. PowerFolder
• Networking:
–2*10GE per server
– 6*10GE on front-end servers, which route
– Two Brocade “ToR” switches with TRILL-based
multi-chassis multipath, L2+VLANs
– 2*10GE towards backbone
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3. Next Step: ~2 * 2 racks with room to scale
Goals:
• Offer “Dropbox-like” service to entire community
• Offer “IaaS” services (VM/storage) to researchers
• A first example of “scientific SaaS”
• Stable and efficient operations
• Scalability, both architectural and economical
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4. Growing the Cloud: Internal fabric
• Beyond a few racks, we need some sort of “aggregation
layer” beyond the ToR. There are multiple approaches:
–Traditional with large aggregation switch (doubled for redundancy)
– Modern with leaf/spine design <- cost-effective “commodity” kit
• How can servers make use of parallelism in the fabric?
– Smart L2 switches (TRILL, Multi-chassis LAG etc.) – vendor lock-in?
– L3 switches with hypervisor-based overlay à la Nicira OVP
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5. Never underestimate the power of Xeon
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6. chur.snabb.co
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7. Performance results
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8. Data Center/Backbone Interface
• Traditionally, you have an access router at each site.
• At >>10 Gb/s, this gets expensive.
• Can we leverage the many cheap 10GEs we have on our
Intel servers?
– Basic (BGP) routing/filtering functionality needed
–Could peer directly with backbone routers in neighboring PoPs
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9. Virtual Private Cloud (VPC)
• Offer customer institutions (university) VMs with IP address
from the university’s range
• Somehow bridge/tunnel these VMs’ interfaces into the
university’s campus network… so that they appear on the
“right” side of the firewall
–What are suitable mechanisms/interfaces at the campus side?
• Also, allow customers to build their own private networks
within our cloud, i.e. between cloud-hosted VMs
– This is now standard functionality in OpenStack/Neutron
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