How to configure and manage cisco nexus switch
- 2. VxLan
- 3. What is VxLan - Virtual Extensible LAN (VXLAN) - provides a way to extend Layer 2 networks across a Layer 3 infrastructure - uses MAC-in-UDP encapsulation and tunneling.
- 4. Benefits of VxLan - This feature enables virtualized and multitenant data center fabric designs over a shared common physical infrastructure. - Flexible placement of workloads across the data center fabric. It provides a way to extend Layer 2 segments over the underlying shared Layer 3 network infrastructure. workloads can be placed across physical pods in a single data center or even across several geographically divers data centers. - Higher scalability to allow more Layer 2 segments. VXLAN uses a 24-bit segment ID, the VXLAN network identifier (VNID). This allows a maximum of 16 million VXLAN segments to coexist in the same administrative domain. Traditional VLANs use a 12-bit segment ID that can support a maximum of 4096 VLANs. - Optimized utilization of available network paths in the underlying infrastructure. VXLAN packets are transferred through the underlying network based on their Layer 3 headers. They use ECMP routing and link aggregation protocols to use all available paths. In contrast, a Layer 2 network might block valid forwarding paths in order to avoid loops.
- 6. VXLAN defines a MAC-in-UDP encapsulation scheme Original Layer 2 frame has a VXLAN header added Then placed in a UDP-IP packet. VXLAN uses an 8-byte VXLAN header that consists of a 24-bit VNID and a few reserved bits. The VXLAN header, together with the original Ethernet frame, go inside the UDP payload. The 24-bit VNID is used to identify Layer 2 segments and to maintain Layer 2 isolation between the segments. With all 24 bits in the VNID, VXLAN can support 16 million LAN segments.
- 8. VID = 12 bits Therefore, only 4096 vlans can be used Further some are reserved
- 9. VNID = 24 bits Therefore, 16 million VNI can be used
- 12. VTEP VXLAN tunnel endpoints (VTEPs) are devices that terminate VXLAN tunnels. They perform VXLAN encapsulation and de-encapsulation. Each VTEP has two interfaces. One is a Layer 2 interface on the local LAN segment to support a local endpoint communication through bridging. The other is a Layer 3 interface on the IP transport network. The IP interface has a unique address that identifies the VTEP device in the transport network. The VTEP device uses this IP address to encapsulate Ethernet frames and transmit the packets on the transport network. A VTEP discovers other VTEP devices that share the same VNIs it has locally connected. It advertises the locally connected MAC addresses to its peers. It also learns remote MAC Address-to-VTEP mappings through its IP interface.
- 13. VTEP Interfaces
- 14. VxLan Underlay and Overlay
- 15. Underlying IP network, called underlay network, is independent of the VXLAN overlay. The underlay network forwards the VXLAN encapsulated packets based on the outer IP address header. The outer IP address header has the initiating VTEP's IP interface as the source IP address and the terminating VTEP's IP interface as the destination IP address. The purpose of the underlay in the VXLAN fabric is to advertise the reachability of VTEP and to give a fast and reliable transport for the VXLAN traffic
- 16. VxLan Overlay Types - L2 overlay - L3 overlay
- 17. VxLan Distributed Anycast gateway
- 18. Distributed Anycast Gateway refers to the use of default gateway addressing that uses the same IP and MAC address across all the leafs that are a part of a VNI. This ensures that every leaf can function as the default gateway for the workloads directly connected to it. The distributed Anycast Gateway functionality is used to facilitate flexible workload placement, and optimal traffic forwarding across the VXLAN fabric.
- 20. VxLan control Plane - Multicast Flood and Learn - MPBGP EVPN
- 21. Flood and Learn Multicast-Based Learning Control Plane When configuring VXLAN with a multicast based control plane, every VTEP configured with a specific VXLAN VNI joins the same multicast group. Each VNI could have its own multicast group, or several VNIs can share the same group. The multicast group is used to forward broadcast, unknown unicast, and multicast (BUM) traffic for a VNI. The multicast configuration must support Any-Source Multicast (ASM) or PIM BiDir. Learning VTEPs only learn local MAC addresses of devices that are directly connected to them. Remote MAC address to VTEP mappings are learned via conversational learning.
- 22. VXLAN MPBGP EVPN Control Plane When the local switch sees the new MAC/IP, it signals the new location to rest of the network. Eliminate or reduce flooding in the data center. Flooding is reduced by distributing MAC reachability information via MP-BGP EVPN to optimize flooding relating to L2 unknown unicast traffic. Optimization of reducing broadcasts associated with ARP is achieved by distributing the necessary information via MPBGP EVPN. The information is then cached at the access switches. The MPBGP EVPN control plane approach provides: • IP reachability information for endpoints • Distribution of host MAC reachability reduces unknown unicast flooding. • Distribution of host IP/MAC bindings helps local ARP suppression. • Host mobility. • A single address family (MPBGP EVPN) to distribute both L2 and L3 route reachability information.
- 24. Vlan to VNID mapping
- 25. Vlan to VNID mapping - different vlan mapping
- 26. Vlan to VNID mapping - Overlapping Vlan mapping across tenants
- 27. VRF to VNID mapping
- 29. Steps to build Multicast Vxlan 1. Build underlay 2. Configure ip reachability between Vtep 3. Configure multicast to allow flood and learn 4. Configure nve
- 30. MP BGP Control Plane
- 31. MPBGP EVPN - Allows for vtep peer discovery and authentication - This control plane mechanism allows us to overcome security risks - Vtep 1st establishes BGP neighbor adjacency with other vteps / RRs - Then BGP updates includes vtep info and end host NLRI - When BGP updates are received, Peer List is also formed - This peer list is also used as Vtep Peer List for authorization
- 32. MPBGP EVPN steps - Step1: local vtep completes local learning - Step2: local vtep advertises learned info to remote vteps using BGP - Step3: local vtep also receives info from remote vteps using BGP
- 33. Comparison of control plane
- 34. Packet Flow