2. ODL SFC, Implementing IETF SFC November 14, 2016
Seoul, South Korea
ODL SFC, Implementing IETF SFC November 14, 2016
Brady Johnson ODL SFC Project Technical Lead

3. OpenDaylight SFC Data Model
Service Function Chain (SFC)
Abstract, ordered list of Service Function Types
ex: [DPI, FW, NAT, QoS]
Service Function Path (SFP)
Concrete, directional details about an SFC
Specific transport details (VxLAN-GPE+NSH, Eth+NSH, etc)
Optionally specify concrete Service Functions and Service Function Forwarders
Rendered Service Path (RSP)
The actual service chain, combining info from the SFC and SFP
Includes dynamic runtime representation of SFP resulting from load balancing and/or failover
Service Chaining Classification
Map subscriber/tenant traffic flows to Service Chains
Applies Service Chain Encapsulation (NSH)
Uses IETF ACL matching for traffic flow matching
SFP
SFC
SF-Type1
SF-Type2
SF-Type3
Concrete SF1
Concrete SF2
Concrete SF3
Classifier
RSP
Concrete SFF1
Concrete SFF2

4. OpenDaylight SFC Use Case: SF Reclassification and branching
P2P/BitTorrent ⇒ Blue
HTTP ⇒ Red
HTTP Header Enrichment
P2P Rate
Limiting
SF-DPI
SF-QoS
SF-HTTP
Re-Classify
Feedback
ODL-SFC
Update/Create Service Chains
SFF
br-int
Classifier
Classifier
Internet
Classification Rules
SDN Network

5. Service Chaining Encapsulation: Network Service Headers (NSH)
NSH-Aware Service Functions (decrement NSI on pkt egress)
NSH encapsulated packets:
NSP: NSH Path, Chain ID
NSI: NSH index, Hop in chain
The shown NSI is after being decremented by the SF
SF-NAT
NSH-UnAware
Service Function
SF-HTTP
SF-NAT
Original
packets
NSH Proxy
Classify once:
Encapsulate Chain info
with every packet
1,253
7,254
1,254
7,253
SFF
br-int
SFF
br-int
Classifier
Classifier
1,255
7,254
7,253
Host 2
Host 2
7,255
Host 1
1,253
Original
packets
SDN Network
Original
packets

6. NSH Header and transport details As supported in ODL SFC
Outer Eth hdr
Outer IP hdr
Outer UDP hdr
VxLAN GPE
Inner Eth hdr
Inner IP hdr
Payload
Example 1: NSH encapsulated in VXLAN-GPE
Network Services Header
Service Path:
The Service Chain ID
NSH Base Header
Index:
The hop in the Service Chain
Service Path (24 bit) / Index
Optional Metadata
Example 2: NSH encapsulated in Ethernet
NSH
Outer Eth hdr
Inner Eth hdr
Inner IP hdr
Payload

7. OpenDaylight: Just 1 piece of the puzzle
ODL
NFV
OpenStack
OVS
fd.io
Linux
OPNFV: Integrating it all together

8. OPNFV SFC Compute Node Control Node OVS (br-int) OVSVM VM VM VM
Tacker
Clients
Servers
SF1
SF2
ODL SFC
Open Stack
OVS (br-int)
Ingress Classifier
SFF
Egress Classifier
OVS
Top Of Rack Switch
Legend
VxLAN tunnel SF/SFF
OpenFlow 1.3/OVSDB
Classifier encaps VxLAN-GPE NSH
Original packets, no encap

9. IETF SFC RFC improvements
Terminating SFPs and how to handle SFP egress
rfc Section 4.3, point 2
The specification mentions that the last SFF should remove the SFC encapsulation and send the packet back to the network.
This can be done by any SFC egress boundary node, and shouldnt be required by the last SFF.
Its not always feasible for the SFF to know what to do with the original packet.
When using GBP and Netvirt classifiers, the egress classifier removes the SFC encapsulation, thus acting as an SFC egress boundary node
If the packet is sent back to the network (OpenStack br-int bridge) without SFC encapsulation, and it enters the classifier again, then there will be a loop
Reclassification
Several use cases that can be problematic
TCP proxy
How to handle when the SF generates traffic, which SFP to use
Symmetric classifier
Should be more explicitly specified