BGP-EVPN

Question 1

What is BGP?

Answer 1

Border gateway protocol

Question 2

What is EVPN?

Answer 2

Ethernet VPN (EVPN) is a standards-based BGP control plane to advertise MAC addresses, MAC and IP bindings and IP Prefixes.

Question 3

What are the three main functions of EVPN?

Answer 3

1) Advertise MAC addresses
2) MAC and IP bindings
3) IP prefixes

Question 4

What is the main reason to use EVPN?

Answer 4

Controls/minimizes mac/ip address flooding which scales best in a network with multiple leaf routers.

Question 5

In BGP, what is an RD (route distinguisher)?

Answer 5

It identifies routes belong to a VRF.

Question 6

In BGP, what is a RT (route target)?

Answer 6

It defines which prefixes are imported and exported between bgp peers.

Question 7

What is VXLAN?

Answer 7

It is a layer 2 in a layer 3 overlay tunnel. It’s an ethernet/IP and UDP tunnel using udp port 4789.

Question 8

What are two ways VXLAN utilizes mac/ip learning?

Answer 8

1) flood and learn
2) bgp evpn

Question 9

In BGP, what is an address family?

Answer 9

Allows multi-protcol (MP-BGP) behavior to be defined over a single BGP peering. It carries this information to its’ peers.

Question 10

What are examples of address families?

Answer 10

1) IPv4 unicast and multicast
2) IPv6 unicast and multicast
3) VPNv4
4) CLNP (connection-less network protocol)

Question 11

What information is carried in the EVPN address family?

Answer 11

1) Host MAC
2) Host IP
3) Network
4) VRF
5) VTEP

Question 12

What is the purpose of the underlay network?

Answer 12

It provides reachability information to reach the VTEP (routing).

Question 13

What is the purpose of the overlay network?

Answer 13

It distributes end host information (mac/ip) - which vtep is the end host behind.

Question 14

What is the advantage of using EVPN BGP over data plane/control plane learning?

Answer 14

It supports integrated routing and bridging.

Question 15

True or false: VNIs can be used as layer 3 and layer 2.

Answer 15

True

Question 16

What is a layer 2 VNI?

Answer 16

Used for bridging, and used for the same LAN segment.

Question 17

What is a layer 3 VNI?

Answer 17

Used for routing when traffic has to leave a layer 2 VNI.

Question 18

In BGP EVPN, what is IRB (integrated routing and bridging)?

Answer 18

This allows VTEPS in a VXLAN network to foward both layer 2 and layer 3 traffic.

Question 19

True or false: In BGP EVPN, traffic between different subnets are forwarded through the VXLAN gateways.

Answer 19

True

Question 20

What are two types of IRB (integrated routing and bridging)?

Answer 20

1) Assymmetric
2) Symmetric

Question 21

What is required to enable vxlan bridging and routing?

Answer 21

Configuring a VTI (virtual tunnel interface), such as the configuration command: interface vxlan1

Question 22

What is Direct VXLAN Routing?

Answer 22

Direct VXLAN routing with VXLAN enabled addresses this issue by configuring each VTEP with all VLANs. This allows packets to be VXLAN-bridged to a local VTEP and routed to remote VTEPs.

Question 23

What are the 3 main evpn route types?

Answer 23

1) Route type 2 - MAC to IP mapping to end hosts. L2
2) Route type 3 - Needs to receive BUM traffic from a VNI
3) Route type 5 - VRF to IP prefix. L3

Question 24

What is symmetric IRB (integrated routing and bridging)?

Answer 24

1) Both local and remote vteps perform routing.
2) Routing is over a layer 3 VNI.
3) Bridging only happens on the vlan between the vtep and tenant.

Question 25

What is asymmetric IRB (integrated routing and bridging)?

Answer 25

1) Only ingress vtep performs routing. 2) Once routing is performed, packets are bridged over a layer 2 VNI to the remote vtep. 3) The remote vtep deencapsulates the packets, and they are bridge to the final destination.

Question 26

What is a BGP community?

Answer 26

A BGP community is an optional, transitive BGP attribute that is recognized and passed to other BGP peers. You might see a BGP community as a tag attached to the BGP routes exchanged between two BGP peers.

Question 27

True or false: EVPN is considered the control plane.

Answer 27

True

Question 28

True or false: Vxlan is considered the data plane.

Answer 28

True

Question 29

What are the 2 VRFs used in BGP-EVPN?

Answer 29

1) IP VRF 2) MAC VRF

Question 30

How is IP VRF used?

Answer 30

To build L3 overlay networks.

Question 31

How is MAC VRF used?

Answer 31

Signifies a broadcase domain, used to build L2 overlay networks.

Question 32

What are the two types of VNIs?

Answer 32

1) Layer 2 VNI 2) Layer 3 VNI

Question 33

What are layer 2 VNIs used for?

Answer 33

L2VNI is used to create MAC-VRF

Question 34

What are layer 3 VNIs used for?

Answer 34

L3 VNI used for IP-VRF sometimes we call it Tenant-VRF