2.VTEP ARP Will Not Add VXLAN Header

2.VTEP ARP Will Not Add VXLAN Header

Contents

1.Introduction

2.VTEP ARP will not add VXLAN Header

3.ARP RATE Control

4.VM ARP in EVPN Learning

4.A Interface Mode

4.B Router ID Mode

5.VM ARP in Unicast Learning

5.A Interface Mode

5.B Router ID Mode

6.VM ARP in Multicast Learning

6.A. Inerface Mode

6.B Router ID Mode

1.Introduction

Unicast & Multicast Learning, discoverdestination VTEP through the VM Address Resolution Protocol (ARP).

EVPN Learning discover destination VTEP throughBGP next hope update.

EVPN learning is not going to learning destination VTEP from VM ARP.

VM ARP is always look fordestination endpointnot gateway & also VM ARP will send only when Traffic configure in STC side. If traffic endpoints are in different subnet or in same subnet cases it will always use the destination endpoint.

We are sending two types of ARP that is.

  1. VTEP ARP will not add VXLAN header.
  2. VM ARP with add VXLAN header

2.VTEP ARP will not add VXLAN Header

VTEP ARP will send to gateway address.

Request Packet Capture of VTEP ARP:

Reply Packet Capture of VTEP ARP:

3.ARP RATE Control

VM ARP can be control by rate. We can configure ARP rata based on the use case. To modify the Rate in VXLAN Global option. As show in below image.

4.VM ARP in EVPN Learning

General in EVPN Learning we are not sending ARP, because destination VTEP learning through BGP update.

If we need to send an VM ARP we need to Enable ARP in VXLAN Segment page. As show in the below figures:

If we Enable L3-VNI we will get VNI Type for Trafficbased onVNI Type we will send ARP packet.

We have three option in VNI Type for Traffic: - L2-VNI, L3-VNI & L2 and L3-VNI.

If we select VNI Type for Traffic as L2-VNI then in ARP packet we are picking L2-VNI.

If we select VNI Type for Traffic as L3-VNI then in ARP packet we are picking L3-VNI

If we select VNI Type for Traffic as L2-VNI -L3-VNI then in ARP packet we are going to pick based on VM VNI.

EX:-

If we see above figure VM Device 18is selected Use L3-VNI for Traffic then it is part of L3-VNIthen in ARP packet will have picked L3-VNI

If we see above figure VM Device 16 is not selected Use L3-VNI for Traffic then it is going to use L2-VNI & in ARP packet it will pick L2-VNI

After traffic resolvedif we send a ARP from the Traffic that time we will send to the correct outer destination IP address.

4.A Interface Mode

Configure VTEP in interface mode:

VXLAN Header

  • Outer media access control (MAC) destination address (MAC address of the tunnel endpoint VTEP)
  • Outer MAC source address (MAC address of the tunnel source VTEP)
  • Outer IP destination address (IP address of the Interface tunnel endpoint VTEP)
  • Outer IP source address (IP address of the Interface tunnel source VTEP)
  • Outer UDP header
  • Inner MAC destination address (MAC address of destination endpoint VM)
  • Inner MAC source address (MAC address of Source VM)
  • Outer IP destination address (IP address of the destination endpoint VM)
  • Outer IP source address (IP address of the source endpoint VM)

RequestPacket capture VM ARP:

Reply Packet capture VM ARP:

4.BRouter ID Mode

If we Enable VM ARP in VXLAN Segment when we start protocol before the learning happen we will not send to the correct outer destination IP address in ARP packet because we are not learning the destination IP from the ARP Packet.

Configure VTEP in Route ID mode:

VXLAN Header

  • Outer media access control (MAC) destination address (MAC address of the tunnel endpoint VTEP)
  • Outer MAC source address (MAC address of the tunnel source VTEP)
  • Outer IP destination address (IP address of the Router IDtunnel endpoint VTEP)
  • Outer IP source address (IP address of the Router IDtunnel source VTEP)
  • Outer UDP header
  • Inner MAC destination address (MAC address of destination endpoint VM)
  • Inner MAC source address (MAC address of Source VM)
  • Outer IP destination address (IP address of the destination endpoint VM)
  • Outer IP source address (IP address of the source endpoint VM)

Request Packet capture VM ARP before traffic resolved:

In request packet, we can see outer IP destination address is gateway address, not a destination VTEP address because in EVPN we are not leaning from destination VTEP from ARP.

Request Packet capture VM ARP After traffic resolved:

Right click on the traffic & send the ARP then see the request & reply.

In request packet, we can see outer IP destination address to destination VTEP address because able to be learned the destination VTEP address from BGP nexthop address from the BGP update packet.

Reply Packet capture VM ARP After traffic resolved:

5.VM ARP in Unicast Learning

We can configure VTEP in two modes. Inerface Mode & Router ID mode.

VM ARP we need to configure traffic to send an ARP, if we are not configuration traffic VM ARP are not sent.

5.A Interface Mode

Configure VTEP in interface mode:

VXLAN Header

  • Outer media access control (MAC) destination address (MAC address of the tunnel endpoint VTEP)
  • Outer MAC source address (MAC address of the tunnel source VTEP)
  • Outer IP destination address (IP address of the Interface tunnel endpoint VTEP)
  • Outer IP source address (IP address of the Interface tunnel source VTEP)
  • Outer UDP header
  • Inner MAC destination address (MAC address of destination endpoint VM)
  • Inner MAC source address(MAC address of Source VM)
  • Outer IP destination address (IP address of the destination endpoint VM)
  • Outer IP source address (IP address of the source endpoint VM)

Request Packet Capture VM ARP:

Reply Packet Capture VM ARP:

5.BRouter ID Mode

In Router ID Mode, the outer Header of the VM ARP is pick the Router ID. If the use case need to send source Router ID to destinationRouter ID then we need to configure DUT Router ID in VXLAN Segments as show in Figure 2.B.2

Configure VTEP in Route ID mode:

Figure 2.B.1

Host side we need to configure Router ID address in Segment side. Then ARP will be sent to the Attached VTEP IP Address.

Figure 2.B.2

VXLAN Header

  • Outer media access control (MAC) destination address (MAC address of the tunnel endpoint VTEP)
  • Outer MAC source address (MAC address of the tunnel source VTEP)
  • Outer IP destination address (IP address of the Router ID tunnel endpoint VTEP)
  • Outer IP source address (IP address of the Router ID tunnel source VTEP)
  • Outer UDP header
  • Inner MAC destination address (MAC address of destination endpoint VM)
  • Inner MAC source address (MAC address of Source VM)
  • Outer IP destination address (IP address of the destination endpoint VM)
  • Outer IP source address (IP address of the source VM)

Request Packet capture VM ARP:

Hence in the packet we can see the outer IP address are picked from Router ID.

Reply Packet capture VM ARP:

6.VM ARP in Multicast Learning

We can configure VTEP in two modes. Inerface Mode & Router ID mode. VM ARP we need to configure traffic to send an ARP, if we are not configuration traffic VM ARP are not sent.

6.A. Inerface Mode

Interface mode, VM inner source IP address will be pick from the interface address of the VTEP outer destinationIP address will be sent to multicast address configure in segment page.

Configure VTEP in interface mode:

Configure multicast address in segment:

VXLAN Header

  • Outer media access control (MAC) destination address (MAC address of the Multicast address)
  • Outer MAC source address (MAC address of Source VTEP address)
  • Outer IP destination address (IP address of the Multicast address should be config in VXLAN segment)
  • Outer IP source address (IP address of the Interface source VTEP address)
  • Outer UDP header
  • Inner MAC destination address (MAC address of destination endpoint VM)
  • Inner MAC source address (MAC address of Source VM)
  • Outer IP destination address (IP address of the destination endpoint VM)
  • Outer IP source address (IP address of the source endpoint VM)

Request Packet Capture VM ARP:

We can see the below capture the outer destination MAC & IP address is Multicast address.

Outer source MAC & IP address is source interface of VTEP address.

Reply Packet Capture VM ARP:

We can see the below capture the outer destination MAC & IP address is updated by destination VTEP address

6.B Router ID Mode

Router ID mode, VM inner source Ip address will be picked from the router id of the VTEP & outer destinationIP address will be sent to multicast address configure in segment page.

Configure VTEP in interface mode:

VXLAN Header

  • Outer media access control (MAC) destination address (MAC address of the Multicast address)
  • Outer MAC source address (MAC address of VTEP address)
  • Outer IP destination address (IP address of the Multicast address should be config in VXLAN segment)
  • Outer IP source address (IP address of the Source Router ID of VTEP address)
  • Outer UDP header
  • Inner MAC destination address (MAC address of destination endpoint VM)
  • Inner MAC source address (MAC address of Source VM)
  • Outer IP destination address (IP address of the destination endpoint VM)
  • Outer IP source address (IP address of the source endpoint VM)

Request Packet capture of the VM ARP:

We can see the below capture the outer destination MAC & IP address is Multicast address.

Outer source MAC & IP address is source router id of VTEP address.

Reply Packet capture of the VM ARP:

We can see the below capture the outer destination MAC & IP address is updated by destination VTEP address.

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