Road to CCNP: Day 100

                             

2.3.a LISP =WHERE

EID = endpoint ID RLOC = Routing Locator EID + RLOC = who + location on network ITR, ETR, xTR, ingress egress, router doing both Map server = holds the database of mappings Map resolver = answers to queries about where (RLOC) is something (EID) located

2.3.b VXLAN = GET IT THERE

                                   VNI = VXLan Network Identifier, 24 bits, identifies each individual VXLAN, about 16 million of them

                                   VTEP = VXLAN Tunnel EndPoint, the actual device (physical or virtualized) that encapsulates or de-encapsulates the layer 2 data into VXLAN layer 3 packets

                                                            Can be software (virtualized, as a v-Switch in hypervisor) or hardware (switch, router, firewall) that supports VXLAN

VNI on the layer 2 side, VTEP IP interface on the overlay side

1. H1 transmits a frame for H2
2. Frame arrives on the VNI of SW1
3. There exists a tunnel between H1 and H2 (VNI 5012) so SW1 prepare the frame for the VXLAN tunnel
   1. Find the mapping of H2’s MAC Address to the what VTEP it’s connected to
   1. Add the VXLAN header, which contains the VNI
   1. Add the UDP header (source and destination ports of 4789 and rarely 8472)
   1. Add the overlay SRC and DST IP addresses
4. Send the packet across the underlay
5. SW2 receives and de-encapsulates the data

How do VTEPs know the MAC address of the foreign host?

1. Essentially each VNI is mapped to a multicast IP address
2. Before encapsulation, the VTEP sends an ARP request to the Destination VTEP(specifically, its multicast address)
3. It’s transferred over network thru underlay which has routes
4. Destination VTEP receives ARP request, notes H1’s MAC address and IP mapping for later, and sends the ARP Request to H2
5. H2 replies with ARP Response, and uses the IP-MAC (VTEP, VNI) mapping from the first trip to respond