Router Distinguisher, EIGRP with VRF

[huyan]

Hi everyone,

I am learning EIGRP with VRF. In a tutorial, there is this configuration. I am not sure I understand it correctly, I put a comment  next to each command, could you helpverify them and answer the questions?

ip vrf TEST(create an instance of VRF named TEST)

rd 100:1(100 is the AS, but what is '1' ? )
interface Loopback0

ip vrf forwarding TEST(put Lo0 to the VRF Test)
ip address 192.168.100.2 255.255.255.255
interface FastEthernet0/0
ip vrf forwarding TEST
ip address 192.168.1.1 255.255.255.0


router eigrp 100   
address-family ipv4 vrf TEST    (Set EIGRP for vrf TEST)
network 192.168.0.0 0.0.255.255  (advertise network 192.168.0.0 0.0.255.255 to all routers with VRF in AS 100)
no auto-summary
autonomous-system 100   (Why do we need to specify AS 100 again? Isn't it being under the configuration of EIGRP 100?)
exit

Thank you!

[Meheretab Mengistu · Accepted solution]

rd

(Route Distinguisher) is a value added to an IPv4 Prefix to to change them into globally unique VPN-IPv4 prefixes.

An

RD

is either:

       - ASN-related--Composed of an autonomous system number and an

arbitrary number

 In your case 100:1 where 100 is AS number and 1 is an

arbitrary number

       - IP-address-related--Composed of an IP address and an 

arbitrary number

autonomous-system

in address-family is used to configure the autonomous-system number for an EIGRP routing process to run within a VRF instance. In your case, the autonomous-system associated with the

router eigrp 100

is for the general routing table; it is not for the VRF. You can also do

address-family ipv4 vrf TEST autonomous-system 100

in recent versions:

router eigrp 100   
  address-family ipv4 vrf TEST autonomous-system 100
  network 192.168.0.0 0.0.255.255   ! Enable EIGRP on all interfaces within the VRF whose ip address is in 192.168.0.0/16 
  no auto-summary
exit

HTH,

Meheretab

[huyan]

Hi Meheretab,
I really appreciate your help, your explanation have cleared out my confusion regarding configuration of EIGRP with VRF.
Thank you!
Best,
Huy.