Flow OAM Requirements Janardhanan Pathangi Balaji Venkat Venkataswami DELL Richard Groves – Microsoft Peter Hoose – Facebook Presenter : Shivakumar Sundaram

TraceFlow Overview Host A Host B Multiple paths between Host A and Host B Network would be using ECMP / LAG for data flow between A and B Tracing the path for a particular flow is problem Ping, Traceroute give reachability between nodes A and B This is not necessarily the path that a particular flow from A to B would take Tool needed to trace the exact path a particular flow would take Tool needed to identify all paths that exist between nodes A and B

Other Requirements The OAM probes while sharing fate with the actual flow, should not affect the real application in progress at the time of troubleshooting. When tracing the flow from node A to node B, it should be possible to direct all the response packets to a third node C, which could be a monitoring tool. The tools under this framework should have the capability to terminate the trace at a specific hop specified as an IP address. This helps in segmented tracing, where parts of the path can be traced. Packet drops and their reasons such as Access list based drops, Egress Administratively disabled and Routing Failures The operator may need to know the utilization of the links along the path in addition to the fan-out information. The tracing of a fat-tree (i.e. all paths) from the source to the destination is a very important requirement from modern day administrators running say a campus network or a data-center. Finding range of ports that go through a specific ECMP / LAG member

Traceflow Protocol July 7, 2011

Option (1) : TraceFlow data path MAC DA MAC SA VLAN Info DST IP SRC IP Protocol, SRC/DST Port MAC DA1 MAC SA1 VLAN Info 1 DST IP SRC IP Protocol, SRC/DST Port MAC DA MAC SA VLAN Info DST IP SRC IP UDP, TraceFlow Port Packet Info TraceFlow Packet TraceFlow HDR TraceFlow packet captured to CPU using UDP, Port Numbers CPU injects the inner packet and has the switch perform a regular Lookup Result is trapped back to the CPU and gives the egress port, and egress Encap that would have been used MAC DA MAC SA VLAN Info DST IP SRC IP UDP, TraceFlow Port TraceFlow RSLT TraceFlow HDR MAC DA 1 MAC SA 1 VLAN Info 1 DST IP SRC IP UDP, TraceFlow Port TraceFlow HDR Packet Info

Trace All Paths Source R1 R2 R3 Dest Request packet Response packet Router R2 & R3 are ECMP paths for R1

Option (2) : Traceroute Version II Put in the actual flow headers in the Traceroute packet including source port and destination port. Termination condition is a challenge – Malformed packet needs to be sent to the destination so that it is dropped by the end application. Use ICMP extensions in RFC 5837 – Extend ICMP extensions to include additional TLVs required.

Option (2) : Traceroute Version II data path MAC DA MAC SA VLAN Info DST IP SRC IP Protocol, SRC/DST Port MAC DA1 MAC SA1 VLAN Info 1 DST IP SRC IP Protocol, SRC/DST Port MAC DA MAC SA VLAN Info Flow DST IP Flow SRC IP Flow source port and Dest port with malformed header Traceroute Packet Sample Payload Traceroute packet sent to destination with actual src, dst IP and src, dst port with malformed header. When the packet reaches the destination it should be dropped and NOT processed. Should ensure that no security loopholes be raised in middleboxes like firewalls. MAC DA MAC SA VLAN Info Flow DST IP Flow SRC IP Flow source port and Dest port ICMP Response MAC DA 1 MAC SA 1 VLAN Info 1 Flow DST IP Flow SRC IP Flow src, Dst Port Malformed Pkt Sample Payload

Comparison Traceroute Version II with Traceflow Traceroute ProposalTraceflow Proposal Packet details in outside headerPacket details in inner payload Termination condition a problemTermination condition NOT a problem Fan-out trace NOT possible. Other solutions like SNMP need involved co- relation in the RFC 4292 MIB. Fan-out trace POSSIBLE in Traceflow with minimum of fuss Not available in RFC 5837 or in other Traceroute TLVs not in traceroute ICMP extensions (a) Hash parameters TLV, (b) Utilization Anomaly TLV, (c) Termination TLV, (d) Indirect option TLV, (e) Additional Result codes Does not need change in router to do special processing Requires some changes in routers to do some additional processing. 9

Directions The original draft had both requirements and the proposal for traceflow We intend to submit the requirements as a separate draft followed by solutions under this framework as separate documents. We would like to get feedback on both requirements and the solution.

Acknowledgements & References We would like to thank Ron Bonica for his in inputs and review. The IETF draft of this proposal can be found at intarea-traceflow-00 intarea-traceflow-00