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Arista VXLAN Routing Cheat Sheet (DRAFT) by

Intro to Arista VXLAN Routing and Recirculation

This is a draft cheat sheet. It is a work in progress and is not finished yet.

VXLAN Routing

VXLAN routing is the routing of traffic between extended L2 domains using VTEPs as the default gateways. Routing can be achieved via a direct or indirect routing model. In the "­dir­ect­" version, packets bridge to their gateway, route on that same device, then bridge across the VXLAN overlay. With the "­ind­ire­ct" model, only a subset of the overlay tenant networks will get locally routed instead of all of the overlay networks. The other networks will use a transit VNI for routing.
If needed, see "­Arista VXLAN Bridging Cheat Sheet" for a review of the basics of VXLAN.

Example Topology

VXLAN and NAT cannot coexist on a switch.

VXLAN and MPLS cannot coexist on a switch.

VXLAN Routing by Platform

Platform
Additional config needed due to asic limita­tions (as of 4.18.1F)
7150
Good to go
7050X
Configure recirc­ulation
7050X2
Good to go
7050X3­,7300X3
Good to go
7250X
Good to go
7060CX, 7260QX
Configure recirc­ulation
7280E
Configure TCAM profile using "­har­dware tcam profile vxlan-­rou­tin­g"
7500E
Not supported
7280R,­7500R
Configure TCAM profile using "­har­dware tcam profile vxlan-­rou­tin­g"
Please see block on how to configure recirc­ulation channels.

Recirc­ulation using front-­panel ports

interface Recirc-Channel627
  switchport recirculation features vxlan
!
interface Ethernet1/2
  traffic-loopback source system device mac
  channel-group recirculation 627
!
interface Ethernet1/3
  traffic-loopback source system device mac
  channel-group recirculation 627

Recirc­ulation using Unconn­ect­edE­thernet Interfaces

service interface unconnected expose
!
interface UnconnectedEthernet2
  traffic-loopback source system device mac
  channel-group recirculation 627
!
On the 7050X (but not on the 7060CX or 7260QX series), the entire chip BW is not used by the front panel ports and can be used for recirc­ulation via this method. It is recomm­ended to set the recirc­ulation BW to match the uplink BW facing the spines. To learn more about this, please contact Arista or see the below:

https:­//w­ww.a­ri­sta.co­m/a­sse­ts/­dat­a/p­df/­use­r-m­anu­al/­um-­eos­/Ch­apt­ers­/VX­LAN.pdf

Confir­mation

show recirc­-ch­annel X
To confirm config­uration
 

Base Config­uration of a Routing VTEP

interface Vxlan1
  vxlan source-interface Loopback1
  vxlan udp-port 4789
  vxlan vlan 15 vni 10015
  vxlan vlan 240 vni 8358534
  vxlan vlan X vni Y
  vxlan flood vtep <remote VTEP IP> <remote VTEP IP>
!
interface Loopback1
   ip address 1.0.1.1/32 << VTEP IP
   ip address 1.0.1.2/32 secondary << Virtual VTEP IP (VVTEP)
!
ip virtual-router mac-address 00:00:11:22:33:44
!
ip routing
!
Notice the only difference with this portion of the config is adding a secondary IP known as the Virtual VTEP IP. This is only needed on routing VTEPs and not on bridgi­ng-only VTEPs. On bridging VTEPs, this VVTEP IP will be included in the flood list to ensure BUM traffic reaches all VTEPs. Don't forget to add the virtual MAC which binds with all Virtual IPs configured on the switch. See "­Arista VXLAN Direct Routin­g" for additional inform­ation.

Direct or Indirect Routing?

See "­Arista VXLAN Direct Routin­g" or "­Arista VXLAN Indirect Routin­g" Cheat Sheets for details.

Config­uration of the SVIs (Anycast Gateways)

Using VARP:
 
Using "ip address virtua­l":
interface Vlan15
 
interface Vlan15
ip address 1.0.15.1/24
 
ip address virtual 1.0.15.254/24
ip virtua­l-r­outer address 1.0.15.254
ip virtua­l-r­outer mac-ad­dress 00:00:­11:­22:­33:44
 
ip virtua­l-r­outer mac-ad­dress 00:00:­11:­22:­33:44
There are two options when config­uring anycast gateways. VARP, commonly seen with MLAG, uses more IP addresses - a physical and a virtual IP address. "ip address virtua­l" only uses a virtual IP address. There are some consid­era­tions when using "ip address virtua­l" - see the relevant block for more info. For more info on VARP, please see the "­Arista VARP" Cheat Sheet.

Consid­era­tions with "ip address virtua­l"

Must configure a secondary IP (matching MLAG peer and all other routing VTEPs) on VXLAN loopback for virtual VTEP IP.
Routing adjace­ncies can't form over SVIs configured with "ip address virtua­l".
In MLAG config, ARP responses to the SVI's VIP are synced with the MLAG peer to ensure consis­tency between the peers. This is achieved via the VXLAN agent so the "ip address virtua­l" option is only available in a VXLAN config.
No periodic GARP is sent (like is sent in VARP).
For non-VXLAN VLANs, use VARP (ip virtua­l-r­outer address).

Config­uring a TCAM hardware profile post 4.20.1F

sw(config)#hardware tcam
sw(config-hw-tcam)#system profile vxlan-routing

sw(config-hw-tcam)#show hardware tcam profile

ARP and MAC Aging Timers

To reduce the potential for traffic flooding when the MAC ages out, configure (interface level) the ARP aging timer to equal or less than the MAC Aging timer.

(confi­g-i­f)#arp timeout 14400

(confi­g)#mac addres­s-table aging-time 14400
       

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