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External Peering

Hedgehog Fabric uses Border Leaf concept to exchange VPC routes outside the Fabric and providing L3 connectivity. External Peering feature allows to set up an external peering endpoint and to enforce several policies between internal and external endpoints.

Hedgehog Fabric does not operate Edge side devices.

Overview

Traffic exit from the Fabric is done on Border Leafs that are connected with Edge devices. Border Leafs are suitable to terminate l2vpn connections and distinguish VPC L3 routable traffic towards Edge device as well as to land VPC servers. Border Leafs (or Borders) can connect to several Edge devices.

External Peering is only available on the switch devices that are capable for sub-interfaces.

Connect Border Leaf to Edge device

In order to distinguish VPC traffic Edge device should be capable for - Set up BGP IPv4 to advertise and receive routes from the Fabric - Connect to Fabric Border Leaf over Vlan - Be able to mark egress routes towards the Fabric with BGP Communities - Be able to filter ingress routes from the Fabric by BGP Communities

All other filtering and processing of L3 Routed Fabric traffic should be done on the Edge devices.

Control Plane

Fabric is sharing VPC routes with Edge devices via BGP. Peering is done over Vlan in IPv4 Unicast AFI/SAFI.

Data Plane

VPC L3 routable traffic will be tagged with Vlan and sent to Edge device. Later processing of VPC traffic (NAT, PBR, etc) should happen on Edge devices.

VPC access to Edge device

Each VPC within the Fabric can be allowed to access Edge devices. Additional filtering can be applied to the routes that VPC can export to Edge devices and import from the Edge devices.

API and implementation

External

General configuration starts with specification of External objects. Each object of External type can represent a set of Edge devices, or a single BGP instance on Edge device, or any other united Edge entities that can be described with following config

  • Name of External
  • Inbound routes are marked with dedicated BGP community
  • Outbound routes are required to be marked with dedicated community

Each External should be bound to some VPC IP Namespace, otherwise prefixes overlap may happen.

apiVersion: vpc.githedgehog.com/v1alpha2
kind: External
metadata:
  name: default--5835
spec:
  ipv4Namespace: # VPC IP Namespace
  inboundCommunity: # BGP Standard Community of routes from Edge devices
  outboundCommunity: # BGP Standard Community required to be assigned on prefixes advertised from Fabric

Connection

Connection of type external is used to identify switch port on Border leaf that is cabled with an Edge device.

apiVersion: wiring.githedgehog.com/v1alpha2
kind: Connection
metadata:
  name: # specified or generated
spec:
  external:
    link:
      switch:
        port: # SwitchName/EthernetXXX

External Attachment

External Attachment is a definition of BGP Peering and traffic connectivity between a Border leaf and External. Attachments are bound to Connection with type external and specify Vlan that will be used to segregate particular Edge peering.

apiVersion: vpc.githedgehog.com/v1alpha2
kind: ExternalAttachment
metadata:
  name: #
spec:
  connection: # Name of the Connection with type external
  external: # Name of the External to pick config
  neighbor:
    asn: # Edge device ASN
    ip: # IP address of Edge device to peer with
  switch:
    ip: # IP Address on the Border Leaf to set up BGP peering
    vlan: # Vlan ID to tag control and data traffic

Several External Attachment can be configured for the same Connection but for different vlan.

External VPC Peering

To allow specific VPC have access to Edge devices VPC should be bound to specific External object. This is done via External Peering object.

apiVersion: vpc.githedgehog.com/v1alpha2
kind: ExternalPeering
metadata:
  name: # Name of ExternalPeering
spec:
  permit:
    external:
      name: # External Name
      prefixes: # List of prefixes(routes) to be allowed to pick up from External
      - # IPv4 Prefix
    vpc:
      name: # VPC Name
      subnets: # List of VPC subnets name to be allowed to have access to External (Edge)
      - # Name of the subnet within VPC

Prefixes is the list of subnet to permit from the External to the VPC, e.g. 0.0.0.0/0 for any route including default route. It matches any prefix length less than or equal to 32 effectively permitting all prefixes within the specified one.

Example: Allow ANY IPv4 prefix that came from External - allow all prefixes that match default route with any prefix length

spec:
  permit:
    external:
      name: ###
      prefixes:
      - prefix: 0.0.0.0/0 # Any route will be allowed including default route

Example:

spec:
  permit:
    external:
      name: ###
      prefixes:
      - prefix: 77.0.0.0/8 # Any route that belongs to the specified prefix will be allowed (e.g. 77.0.0.0/8 or 77.1.2.0/24)

Examples

This example will show peering with External object with name HedgeEdge given Fabric VPC with name vpc-1 on the Border Leaf switchBorder that has a cable between an Edge device on the port Ethernet42. vpc-1 is required to receive any prefixes advertised from the External.

Fabric API configuration

External

# hhfctl external create --name HedgeEdge --ipns default --in 65102:5000 --out 5000:65102
apiVersion: vpc.githedgehog.com/v1alpha2
kind: External
metadata:
  name: HedgeEdge
  namespace: default
spec:
  inboundCommunity: 65102:5000
  ipv4Namespace: default
  outboundCommunity: 5000:65102

Connection

Connection should be specified in the wiring diagram.

###
### switchBorder--external--HedgeEdge
###
apiVersion: wiring.githedgehog.com/v1alpha2
kind: Connection
metadata:
  name: switchBorder--external--HedgeEdge
spec:
  external:
    link:
      switch:
        port: switchBorder/Ethernet42

ExternalAttachment

Specified in wiring diagram

apiVersion: vpc.githedgehog.com/v1alpha2
kind: ExternalAttachment
metadata:
  name: switchBorder--HedgeEdge
spec:
  connection: switchBorder--external--HedgeEdge
  external: HedgeEdge
  neighbor:
    asn: 65102
    ip: 100.100.0.6
  switch:
    ip: 100.100.0.1/24
    vlan: 100

ExternalPeering

apiVersion: vpc.githedgehog.com/v1alpha2
kind: ExternalPeering
metadata:
  name: vpc-1--HedgeEdge
spec:
  permit:
    external:
      name: HedgeEdge
      prefixes:
      - prefix: 0.0.0.0/0
    vpc:
      name: vpc-1
      subnets:
      - default

Example Edge side BGP configuration based on SONiC OS

NOTE: Hedgehog does not recommend using following configuration for production. It's just as example of Edge Peer config

Interface config

interface Ethernet2.100
 encapsulation dot1q vlan-id 100
 description switchBorder--Ethernet42
 no shutdown
 ip vrf forwarding VrfHedge
 ip address 100.100.0.6/24

BGP Config

!
router bgp 65102 vrf VrfHedge
 log-neighbor-changes
 timers 60 180
 !
 address-family ipv4 unicast
  maximum-paths 64
  maximum-paths ibgp 1
  import vrf VrfPublic
 !
 neighbor 100.100.0.1
  remote-as 65103
  !
  address-family ipv4 unicast
   activate
   route-map HedgeIn in
   route-map HedgeOut out
   send-community both
 !
Route Map configuration
route-map HedgeIn permit 10
 match community Hedgehog
!
route-map HedgeOut permit 10
 set community 65102:5000
!

bgp community-list standard HedgeIn permit 5000:65102


Last update: April 1, 2024
Created: December 20, 2023