EVPN for Layer 2 stretch between Data Centers Pt.1

EVPN (Enhanced VPN or Ethernet VPN) is a great technology for stretching Layer 2 between Data Centers (aka Data Center Interconnect or DCI). It uses MP-BGP for control plane exchange of Tenant information and mac-addresses. Data Plane traffic is tunneled inside a tunneling protocol such as MPLS, VXLAN or PBB. EVPN is used in lieu of VPLS because it provides better control over BUM traffic (Broadcast, Unknown Unicast, and Multicast). It also supports the ability to forward traffic over multiple active paths and Multihoming. EVPN used over MPLS provides the benefits of traffic engineering and fast convergence.

In part I, I've created a small single-homed setup to show how this works.

 

The first step is to create the trunk port facing the Leaf switch. The leaf switch is a standard TOR switch with no special config.

set interfaces et-2/2/1 description TO-LEAF1

set interfaces et-2/2/1 flexible-vlan-tagging
set interfaces et-2/2/1 encapsulation flexible-ethernet-services
set interfaces et-2/2/1 unit 100 encapsulation vlan-bridge
set interfaces et-2/2/1 unit 100 vlan-id 100
 

I created a sub-interface and placed it into a routing instance.

set routing-instances evpn100 instance-type evpn

set routing-instances evpn100 vlan-id 100
set routing-instances evpn100 interface et-2/2/1.100
set routing-instances evpn100 route-distinguisher 4.4.4.4:100
set routing-instances evpn100 vrf-target target:65000:100
set routing-instances evpn100 protocols evpn interface et-2/2/1.100
set routing-instances evpn100 protocols evpn label-allocation per-instance

Instance configuration looks like a normal VPLS configuration except for the instance-type and evpn protocol parameters.

Next I configure BGP to exchange control plane info.

set protocols bgp group IBGP type internal

set protocols bgp group IBGP local-address 4.4.4.4
set protocols bgp group IBGP family inet unicast
set protocols bgp group IBGP family evpn signaling
set protocols bgp group IBGP neighbor 5.5.5.5

A new address family is used called evpn.

After that, the normal MPLS, your flavor of MPLS signaling and IGP protocol configuration is used as well as the Core MPLS facing interfaces.

set protocols mpls interface all

set protocols mpls interface fxp0.0 disable
set protocols mpls interface lo0.0
set protocols isis interface all
set protocols isis interface fxp0.0 disable
set protocols isis interface lo0.0 passive
set protocols ldp interface all
set protocols ldp interface fxp0.0 disable
set protocols ldp interface lo0.0

set interfaces et-2/0/0 description TO-CORE1
set interfaces et-2/0/0 unit 0 family inet address 192.168.24.4/24
set interfaces et-2/0/0 unit 0 family iso
set interfaces et-2/0/0 unit 0 family mpls


Once configured, MP-BGP exchanges "control plane" information.

# run show bgp summary
Groups: 1 Peers: 1 Down peers: 0
Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending
inet.0              
                       0          0          0          0          0          0
bgp.evpn.0          
                       2          2          0          0          0          0
Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State|#Active/Received/Accepted/Damped...
5.5.5.5               65000        137        136       0       0       57:42 Establ
  inet.0: 0/0/0/0
  bgp.evpn.0: 2/2/2/0
  evpn100.evpn.0: 2/2/2/0
  __default_evpn__.evpn.0: 0/0/0/0


# run show route receive-protocol bgp 5.5.5.5

inet.0: 24 destinations, 24 routes (24 active, 0 holddown, 0 hidden)

inet.3: 3 destinations, 3 routes (3 active, 0 holddown, 0 hidden)

iso.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)

mpls.0: 15 destinations, 15 routes (15 active, 0 holddown, 0 hidden)

bgp.evpn.0: 2 destinations, 2 routes (2 active, 0 holddown, 0 hidden)
  Prefix          Nexthop           MED     Lclpref    AS path
  2:5.5.5.5:100::100::00:00:05:ed:ae:01/304                  
*                         5.5.5.5                      100        I
  3:5.5.5.5:100::100::5.5.5.5/304                  
*                         5.5.5.5                      100        I

evpn100.evpn.0: 4 destinations, 4 routes (4 active, 0 holddown, 0 hidden)
  Prefix          Nexthop           MED     Lclpref    AS path
  2:5.5.5.5:100::100::00:00:05:ed:ae:01/304                  
*                         5.5.5.5                      100        I
  3:5.5.5.5:100::100::5.5.5.5/304                  

You can also check the status of the EVPN and it's mac table


# run show evpn mac-table

MAC flags (S - static MAC, D - dynamic MAC, L - locally learned, P - Persistent static, C - Control MAC
           SE - statistics enabled, NM - non configured MAC, R - remote PE MAC)


Ethernet switching table : 2 entries, 2 learned
Routing instance : evpn100
    Vlan                MAC                 MAC         Age    Logical                NH        RTR
    name                address             flags              interface              Index     ID
    __evpn100__         00:00:05:ed:ad:49   D             -   et-2/2/1.100        
    __evpn100__         00:00:05:ed:ae:01   DC            -   pip-13.010010000000    1048577   1048577


This shows you locally learned macs and macs learned over the WAN.

# run show evpn statistics   
Instance: evpn100
   Local interface: et-2/2/1.100, Index: 338
     Broadcast packets:                     1
     Broadcast bytes  :                    60
     Multicast packets:                     0
     Multicast bytes  :                     0
     Flooded packets  :                  4240
     Flooded bytes    :               6341604
     Unicast packets  :               3292539
     Unicast bytes    :            3528822524
     Current MAC count:                     1 (Limit 0)

In Part II I'll go more into configuring Gateway information to prevent the trombone effect.