Virtual extensible Local Area Network
A L2 in L3 overlay tunnel
- Specifically an ethernet in UDP tunnel
- technically agnostic to the data plane encapsulation
Why use VxLAN
- expands vlan name space : vlan 2power12
- vxlan 2power24
- Allows layer 2 multipathing
- don't need stp for loop prevention
- uses layer 3 ECMP over CLOS fabric
- similar login to fabricpath
- Includes scaling enhancements
- Optimizes control plane, e.g MAC learning , ARP Tables, BUM replication etc.
- Dose not break layer 2 adjacency requirements
- Allows for any to any stateless layer 2 & layer 3 transport E.g vMotion
- Allows for multi tenancy
- Separations of customer traffic over shared underlay fabric
- Allows for overlapping L2 & L3 addresses e.g VLANs & ips are locally significant
VxLAN Terminology
- Underlay Network: Provides transport for VxLAN , i.e ospf , eigrp , is-is routed fabric
- overlay Network : Uses the service provided by VxLAN
- VNI/VNID : VxLAN network Identifier
- VTEP : VxLAN tunnel end point
- Box that performs VxLAN encap/decap
- Could by H/W or S/W
- E.g Nexus 5600 vs Nexus 1000V
- VxLAN segment : - the resulting layer 2 overlay n/w
- VxLAN Gateway
- Device that forwards traffic between Vxlans
- Can be both L2 & L3 forwarding
- NVE : Network Virtualization Edge
- Logical representation of the VTEP
- i.e NVE is the tunnel interface
VxLAN Encapsulation :
Basic VxLAN Workflow:
- Receive ARP From local host
- Assume a miss occurs
- Find the remote VTEP
- Multicast flood & Learn
- Ingress replication
- MP-BGP L2VPN EVPN
- Unicast encap frame towards the VTEP
- Throws away the VLAN
- Replace it with the VNID
No comments:
Post a Comment