E-VPN and Data Center

E-VPN and Data Center

R. Aggarwal (rahul@juniper.net)

Reference Model and Terminology

“WAN”

DCS1

DCB3

DCS2

DCB1

DCS8

Data Center 1

Data Center 3

DCS5

DCS4

DCB4/DCS9

DCB2

Data Center 2

Data Center 4

Client Site BR

DC: Data Center DCS: Data center switch Connected to Servers/VMs DCB: Data center border router Could be co-located with DCS “WAN” provides interconnect among DCs, and between DCs and Client Site BR

Client site

Data Center Interconnect: Layer 2 Extension

“WAN”

DCB3

DCS1

DCS8

DCB1

DCS2

Data Center 3

Data Center 1

DCS5

DCB4/DCS9

DCS4

DCB2

Data Center 4

Data Center 2

Client Site BR

VLAN1 (subnet1) stretches between DC1, DC2, DC3 and DC4 VLAN2 (subnet2) is present only on DCS1

VLAN3 (subnet3) stretches between DC1 and DC2 VLAN stretch is required for cloud computing “resource fungibility”, redundancy etc. Communication between VMs on different VLANs/subnets and between clients and the VMs requires layer 3 routing

Client site

VM4

VM1

VM2

VM7

VM3

VM6

VM8

VM5

BGP-MPLS E-VPNs for Data Center Interconnect

BGP-MPLS based technology, one application of which is data center interconnect between data center switches for intra-VLAN forwarding i.e., layer 2 extension Why? Not all data center interconnect layer 2 extension requirements are satisfied by existing MPLS technology such as VPLS E.g., minimizing flooding, active-active points of attachment, fast edge protection, scale, etc. How? Reuses several building blocks from existing BGP-MPLS technologies Requires extensions to existing BGP-MPLS technologies Draft-raggarwa-sajassi-l2vpn-evpn-01.txt Being pursued in the L2VPN WG

E-VPN Reference Model

RR

MES - MPLS Edge Switch; EFI – E-VPN Forwarding Instance; ESI – Ethernet Segment Identifier (e.g., LAG identifier) MESes are connected by an IP/MPLS infrastructure Transport may be provided by MPLS P2P or MP2P LSPs and optionally P2MP/MP2MP LSPs for “multicast” Transport may be also be provided by IP/GRE Tunnels

VPN A

MES 4

ESI 1, VLAN1

Host-A4

Host -A1

ESI 3, VLAN1

Ethernet Switch-B3

VPN A

MES 2

ESI 1, VLAN1

VPN B

ESI 4, VLAN2

Host –A5

ESI 2, VLAN2

ESI 5, VLAN1

MES 1

Host-A3

VPN B

Host-B1

VPN A

MES 3

EFI-A

EFI-A

EFI-A

EFI-B

EFI-B

Relating EVPN Reference Model to Data Center Interconnect Reference

Model

“WAN”

DCS2

DCS1

DCS8

DCS5

DCS4

DCB3

DCB1

Data Center 1

Data Center 3

DCB4/DCS9

DCB2

Data Center 4

Data Center 2

DCSes may act as MPLS Edge Switches (MES) DCSes may interconnect with DCBs using E-VPN DCSes are connected to hosts i.e., VMs DCBs must participate in E-VPN although they may perform only MPLS switching WAN routers may or may not participate in E-VPN Following slides will describe an overview of E-VPN and then apply E-VPN to data center interconnect

E-VPN Local MAC Address Learning

A MES must support local data plane learning using vanilla ethernet learning procedures When a CE generates a data plane packet such as an ARP request MESes may learn the MAC addresses of hosts in the control plane using extensions to protocols that run between the MES and the hosts MESes may learn the MAC addresses of hosts in the management plane

E-VPN Remote MAC Address Learning

E-VPN introduces the ability for an MES to advertise locally learned MAC addresses in BGP to other MESes, using principles borrowed from IP VPNs E-VPN requires an MES to learn the MAC addresses of CEs connected to other MESes in the control plane using BGP Remote MAC addresses are not learned in the data plane

Remote MAC Address Learning in the BGP Control Plane Architectural

Benefits

Increases the scale of MAC addresses and VLANs supported BGP capabilities such as constrained distribution, Route Reflectors, inter-AS etc., are reused Allows hosts to connect to multiple active points of attachment Improves convergence in the event of certain network failures Allow hosts to relocate within the same subnet without requiring renumbering Minimizes flooding of unknown unicast packets Minimizes flooding of ARP Rest of the presentation will focus on this Control over which MAC addresses are learned by which devices Simplifies operations; enables flexible topologies etc.

ARP Scaling Optimization: Approach

Minimize the radius of ARP request/response propagation Minimize the propagation radius of ARP request from a server/Virtual Machine In the switching infrastructure in the data center Across data centers Respond to an ARP request from a server/VM as close to the server/VM as possible Requires a number of components See the following slide

ARP Scaling Optimization: Proxy ARP

A network node as close to the server/VM, as possible, performs “Proxy ARP” in response to ARP requests from the server/VM The network node should ideally be the DCS Which MAC address does the network node use to respond to the ARP request? The answer depends on the forwarding paradigm used by the node to forward packets within the VLAN MAC lookup based forwarding within the VLAN/subnet The solution in the following slides focuses on this IP address based forwarding within the VLAN/subnet Not discussed in the following slides

MESes perform Proxy ARP An MES responds to an ARP request, for an IP

address, with the MAC address bound to the IP address When the destination is in the same subnet as the sender of the ARP request The ARP request is not forwarded to other MESes

ARP Scaling Optimization: The Role of E- VPN (1) When MAC lookup based forwarding is used within a VLAN/subnet

ARP Scaling Optimization: The Role of E- VPN (2)

How does the MES learn the IP address bound to the MAC address when the MAC address is remote? BGP MAC routes carry the IP address bound to the MAC address How does an MES learn the IP to MAC binding when the MAC address is local? Control or management plane between MES and CEs or data plane snooping An MES advertises the local IP to MAC bindings in the MAC routes