Presentation on theme: "L3 + VXLAN Made Practical. OpenStack Summit Spring 2014 Who We Are Nolan Leake Cofounder, CTO Cumulus Networks Chet Burgess Vice President, Engineering."— Presentation transcript:
OpenStack Summit Spring 2014 L3: A better design IP Fabrics Are Ubiquitous – Proven at scale (The Internet, massive datacenter clusters) Simple Feature Set – no alphabet soup of L2 protocols Scalable L2/L3 Boundary ECMP – Equal Cost Multi-Path – Each link is active at all times – Maximize link utilization – Predictable latency – Better failure handling
OpenStack Summit Spring 2014 L3: A better design
Pure L3 is great for maximizing connectivity, but what about segregation of projects?
OpenStack Summit Spring 2014 VXLAN: Virtual eXtensible LAN IETF Draft Standard – http://www.ietf.org/id/draft-mahalingam-dutt-dcops- vxlan-09.txt http://www.ietf.org/id/draft-mahalingam-dutt-dcops- vxlan-09.txt A type of network overlay technology that encapsulates L2 frames as UDP packets
OpenStack Summit Spring 2014 VXLAN: Virtual eXtensible LAN
OpenStack Summit Spring 2014 VXLAN: Virtual eXtensible LAN VNI – VXLAN Network Identifier – 24 bit number (16M+ unique identifiers) – Part of the VXLAN Header – Similar to VLAN ID – Limits broadcast domain VTEP – VXLAN Tunnel End Point – Originator and/or terminator of VXLAN tunnel for a specific VNI – Outer DIP/Outer SIP
OpenStack Summit Spring 2014 VXLAN: Virtual eXtensible LAN Sending a packet – ARP table is checked for IP/MAC/Interface mapping – L2 FDB is checked to determine IP of destination VTEP for destination MAC on source VTEP
OpenStack Summit Spring 2014 VXLAN: Virtual eXtensible LAN Sending a packet – Packet is encapsulated for destination VTEP with configured VNI and sent to destination – Destination VTEP un-encapsulates the packet and the inner packet is then processed by the receiver
How do VTEPs handle BUM (Broadcast, Unknown Unicast, Multicast)?
OpenStack Summit Spring 2014 BUM All BUM type packets (ex. ARP, DHCP, multicast) are flooded to all VTEPs associated with the same VNI. Flooding can be handled 2 ways – Packets are sent to a multicast address that all VTEPs are subscribers of – Packets are sent to a central service node that then floods the packets to all VTEPs found in its local DB for the matching VNI
OpenStack Summit Spring 2014 VXLAN: Virtual eXtensible LAN Well supported in most modern Linux Distros – Linux Kernel 3.10+ Linux uses UDP port 8472 instead of IANA issued 4789 – iproute2 3.7+ Configured using ip link command
OpenStack Summit Spring 2014 nova-network Clients needed L3+VXLAN for their existing nova- network based big data deployments (hadoop). – Neutron already supports VXLAN and should work with L3 as well (we didn’t have time to test it). Full VXLAN support in nova-network Unicast VXLAN service node for BUM flooding
OpenStack Summit Spring 2014 VXLAN Service Node Unicast service for BUM flooding Eliminates the need for multicast Python based 2 Components – VXSND – VXLAN Service Node Daemon – VXRD – VXLAN Registration Daemon Will be open sourced in the near future.
OpenStack Summit Spring 2014 VXSND Listens for VXLAN BUM packets from VTEPs Learns VTEP and VNI endpoints from BUM packets Relays BUM packets to all known VTEPs for given VNI Supports registration/replication from other VXSND daemons or VXRD
OpenStack Summit Spring 2014 VXRD Monitors local interfaces on hypervisors Sends VTEP+VNI registration packet to VXSND node for all local VTEPs.
OpenStack Summit Spring 2014 Software Gateway We’re still getting in/out of the VXLAN network using a software gateway – Lower performance – Extra servers All nova-net (or neutron’s l3agent) is doing is configuring VXLANs, bridges and iptables NAT. – What if we had a hardware switch that could accelerate these standard Linux network features with an ASIC?
OpenStack Summit Spring 2014 Cumulus Linux – Linux Distribution for HW switches (Debian based) – Hardware accelerated Linux kernel forwarding using ASICs – Just like a Linux server with 32 40G NICs, but ~100x faster Standard Linux Tools – Ifconfig, ip route, iptables, brctl, dnsmasq, etc
OpenStack Summit Spring 2014 Next Steps (nova-network VXLAN) nova-network – Blueprint to add VXLAN support to nova-network Juno coming soon. VXSND/VXRD – Update VXRD to monitor netlink for VTEP add/delete – Improve concurrency and scalability of VXSND – Support for tiered replication (TOR, spine, etc) – Goal is to open source the product before Paris summit.
OpenStack Summit Spring 2014 Next Steps (nova-network on Switches) Hack: ASIC can’t route in/out of VXLAN tunnel – Next gin ASICs can – Worked around by looping a cable between two ports Packets take a second trip through the switch Hack: Cumulus Linux doesn’t support NAT – I hacked in just enough NAT support for floating IPs =) Limitation: ASIC can only NAT 512 IPs. /23 – Next gen ASICs will likely have larger tables