VxLAN | Part 2 - Header Format and Encapsulation

now the story of on what network with distributed hosts and the one technology has no choice but to keep them all together is VX Lane encapsulation you know that thing where you start with a small piece of information and you glue more on to it and then some more and then more well you're going to see plenty of that with VX Lane and with that in mind I'd like to welcome you to part 2 of the VX land series in the last video we got to see how VX lane works we saw that VX Lane creates virtual layer 2 segments called V and is V and is right on top of the layer 3 network the X land uses a special interface called the V tab these bridges via Nuys to the layer 3 network when traffic comes in the V tip encapsulates the traffic and sends it to a destination V tab where it is D capsulated in this video we're going to look deeper into the process and look at the headers that VX lane uses we start with an ordinary ethernet frame that a host would send we call this the inner mac frame this includes data MAC address information and other Ethernet fields it may also have a VLAN tag included in our example traffic will stay within the VNA so there's no routing required the host sends the frame to the switch the switch adds a V excellent header which contains the VNA the V tip now adds several additional headers preserving the inner frame the X LAN uses UDP for transport the destination port is 40 789 and the source port is random ecmp if available uses a hashing algorithm to decide which link to put the traffic on the random source port helps this algorithm to utilize the links evenly an IP header is now added with the address of the destination V tip an Ethernet header with a MAC address is added for delivery to the next physical device as normal the source and destination MAC addresses change with each device they pass through when the traffic arrives at the destination V tap the headers are removed leaving the original frame which can now be delivered to the host you of all these headers the VX clan Hatter is the only one that's a bit different all the others are well-known fortunately it's not difficult to decipher there are four parts to the VX LAN header eight bits are reserved for future use this is set to zero and ignored by the receiving V tip the VN I field is 24 bits long and contains the VX LAN ID this large address space is what makes it possible to have so many VN is another 24 bits are reserved as before this field is ignored by the receiver at the start of the frame is eight flag bits right now only bit three is used bit three is the I field which is set to one for a valid V na the rest are reserved and ignored so there's a lot of unused space in the VX Lane header it will be very interesting to see how this is used in future if you have any thoughts on these reserved fields please share them in the comments as you can see adding all these extra headers makes the frame much larger the extra VX LAN UDP and IP headers add up to around 50 bytes of overhead to account for this you will need to enable jumbo frames everywhere otherwise you will get fragmentation which as you know decreases performance in third part of this series we're going to look at the spine lift topology that's so commonly used with the X LAN before moving on please take a moment to subscribe hit the like button and leave me a comment I'll be waiting for you in part 3 you

Channel: Network Direction

Views: 93,651

Keywords: vx lan part2, vxlan process, vxlan header, vxlan part 2, vxlan packet header, vxlan technical deep dive, vxlan deep dive, vxlan packet format, vxlan layer2, layer 2 header, ingress replication, vxlan overlay, vxlan vs vlan, overlay and underlay network nexus, vx lan basic concepts, network operation vxlan, l2 flood and learn vxlan, 4789, frame, ecmp, algorithm, port, ip, networking direction part 2, destination, vxlan explained, network, nexus, explained, underlay routing, architecture

Id: jjr8aIIRkYc

Length: 5min 11sec (311 seconds)

Published: Thu Feb 08 2018