No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>Search

Reminder

To have a better experience, please upgrade your IE browser.

upgrade

NE20E-S V800R010C10SPC500 Feature Description - VPN 01

This is NE20E-S V800R010C10SPC500 Feature Description - VPN
Rate and give feedback:
Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
EVPN VXLAN Fundamentals

EVPN VXLAN Fundamentals

Introduction

Ethernet virtual private network (EVPN) is a VPN technology used for Layer 2 internetworking. EVPN is similar to BGP/MPLS IP VPN. EVPN defines a new type of BGP network layer reachability information (NLRI), called the EVPN NLRI. The EVPN NLRI defines new BGP EVPN routes to implement MAC address learning and advertisement between Layer 2 networks at different sites.

VXLAN does not provide the control plane, and VTEP discovery and MAC addresses learning are implemented by traffic flooding on the data plane, resulting in high traffic volumes on DC networks. To address this problem, VXLAN uses EVPN as the control plane. EVPN allows VTEPs to exchange BGP EVPN routes to implement automatic VTEP discovery and host information advertisement, preventing unnecessary traffic flooding.

EVPN uses extended BGP and defines new BGP EVPN routes to transmit VTEP addresses and host information. As such, the application of EVPN on VXLANs moves VTEP discovery and host information learning from the data plane to the control plane.

BGP EVPN Routes

EVPN NLRI defines the following BGP EVPN route types applicable to the VXLAN control plane:

Type 2 route—MAC/IP route

The Figure 12-32 shows the format of MAC/IP routes.

Figure 12-32 MAC/IP route

The Table 12-3 describes the fields.

Table 12-3 The fields of MAC/IP route

Field

Description

Route Distinguisher

RD value of an EVPN instance

Ethernet Segment Identifier

Unique ID for defining the connection between local and remote devices

Ethernet Tag ID

VLAN ID configured on the device

MAC Address Length

Length of the host MAC address carried in the route

MAC Address

Host MAC address carried in the route

IP Address Length

Mask length of the host IP address carried in the route

IP Address

Host IP address carried in the route

MPLS Label1

Layer 2 VNI carried in the route

MPLS Label2

Layer 3 VNI carried in the route

MAC/IP routes function as follows on the VXLAN control plane:

  • MAC address advertisement

    To implement Layer 2 communication between intra-subnet hosts, the source and remote VTEPs must learn the MAC addresses of the hosts. The VTEPs function as BGP EVPN peers to exchange MAC/IP routes so that they can obtain the host MAC addresses. The MAC Address Length and MAC Address fields identify the MAC address of a host.

  • ARP advertisement

    A MAC/IP route can carry both the MAC and IP addresses of a host, and therefore can be used to advertise ARP entries between VTEPs. The MAC Address and MAC Address Length fields identify the MAC address of the host, whereas the IP Address and IP Address Length fields identify the IP address of the host. This type of MAC/IP route is called the ARP route.

  • IP route advertisement

    In distributed VXLAN gateway scenarios, to implement Layer 3 communication between inter-subnet hosts, the source and remote VTEPs that function as Layer 3 gateways must learn the host IP routes. The VTEPs function as BGP EVPN peers to exchange MAC/IP routes so that they can obtain the host IP routes. The IP Address Length and IP Address fields identify the destination address of the IP route. In addition, the MPLS Label2 field must carry the Layer 3 VNI. This type of MAC/IP route is called the integrated routing and bridging (IRB) route.

    NOTE:

    An ARP route carries host MAC and IP addresses and a Layer 2 VNI. An IRB route carries host MAC and IP addresses, a Layer 2 VNI, and a Layer 3 VNI. Therefore, IRB routes carry ARP routes and can be used to advertise IP routes as well as ARP entries.

Type 3 route—inclusive multicast route

An inclusive multicast route comprises a prefix and a PMSI attribute.

Figure 12-33 Format of an inclusive multicast route

The Table 12-4 describes the fields.

Table 12-4 The fields of an inclusive multicast route

Field

Description

Route Distinguisher

RD value of an EVPN instance

Ethernet Tag ID

VLAN ID

The value is all 0s in this type of route.

IP Address Length

Mask length of the local VTEP's IP address carried in the route

Originating Router's IP Address

Local VTEP's IP address carried in the route

Flags

Flags indicating whether leaf node information is required for the tunnel

This field is inapplicable in VXLAN scenarios.

Tunnel Type

Tunnel type carried in the route

The value can only be 6, representing Ingress Replication in VXLAN scenarios. It is used for BUM packet forwarding.

MPLS Label

Layer 2 VNI carried in the route

Tunnel Identifier

Tunnel identifier carried in the route

This field is the local VTEP's IP address in VXLAN scenarios.

This type of route is used on the VXLAN control plane for automatic VTEP discovery and dynamic VXLAN tunnel establishment. VTEPs that function as BGP EVPN peers exchange inclusive multicast routes to transfer Layer 2 VNIs and VTEPs' IP addresses. The Originating Router's IP Address field identifies the local VTEP's IP address; the MPLS Label field identifies a Layer 2 VNI. If the remote VTEP's IP address is reachable at Layer 3, a VXLAN tunnel to the remote VTEP is established. If the remote VNI is the same as the local VNI, an ingress replication list is created for subsequent BUM packet forwarding.

Type 5 route—IP prefix route

The Figure 12-34 shows the format of IP prefix routes.

Figure 12-34 IP prefix route

The Table 12-5 describes the fields.

Table 12-5 The fields of IP prefix route

Field

Description

Route Distinguisher

RD value of an EVPN instance

Ethernet Segment Identifier

Unique ID for defining the connection between local and remote devices

Ethernet Tag ID

VLAN ID configured on the device

IP Prefix Length

Length of the IP prefix carried in the route

IP Prefix

IP prefix carried in the route

GW IP Address

Default gateway address

This field is inapplicable in VXLAN scenarios.

MPLS Label

Layer 3 VNI carried in the route

The IP Prefix Length and IP Prefix fields in an IP prefix route can identify a host IP address or network segment.

  • If the IP Prefix Length and IP Prefix fields in an IP prefix route identify a host IP address, the route is used for IP route advertisement in distributed VXLAN gateway scenarios, which functions the same as an IRB route on the VXLAN control plane.

  • If the IP Prefix Length and IP Prefix fields in an IP prefix route identify a network segment, the route allows external network access.

Translation
Download
Updated: 2019-01-03

Document ID: EDOC1100055135

Views: 10231

Downloads: 19

Average rating:
This Document Applies to these Products
Related Documents
Related Version
Share
Previous Next