Hello Alan,
Good question. In this case the SVR peer is established over a routed network, so all we need to peer is to find that interfaces gateway address and ensure that the gateways respond to ARP.
Looking at the Branch1 Router, we are sending the BFD packet towards 3.3.3.128 via 1.1.1.1:
admin@branchoffice1.seattlesite1# show arp
Wed 2019-03-20 15:45:56 UTC
Node: branchoffice1
========== ====== ================ =================== =======
Dev Name VLAN IP Dest MAC State
========== ====== ================ =================== =======
lan1 0 192.168.64.254 52:54:00:cb:c1:3b Valid
mpls1 0 10.0.128.1 52:54:00:25:19:24 Valid
wan1 0 1.1.1.1 52:54:00:88:6b:6d Valid
Completed in 0.04 seconds
admin@branchoffice1.seattlesite1# show peers
Wed 2019-03-20 15:46:01 UTC
============= =============== =========== ============= ====== ======== ============= =============
Peer Node Interface Destination Vlan Status Hostname Path MTU
============= =============== =========== ============= ====== ======== ============= =============
bostonsite1 branchoffice1 mpls1 10.0.128.1 0 up unavailable unavailable
bostonsite1 branchoffice1 wan1 3.3.3.128 0 up unavailable unavailable
And on the datacenter side, the BFD packets are sent to 1.1.1.128 via 3.3.3.1:
admin@datacenter1.bostonsite1# show arp
Wed 2019-03-20 15:52:58 UTC
Node: datacenter1
========== ====== ============== =================== =======
Dev Name VLAN IP Dest MAC State
========== ====== ============== =================== =======
mpls1 0 10.0.128.0 52:54:00:e5:b9:0a Valid
srv1 0 172.16.128.2 52:54:00:6f:45:f8 Valid
srv2 0 172.26.128.2 52:54:00:ed:18:f4 Valid
wan1 0 3.3.3.1 52:54:00:46:d3:99 Valid
Completed in 0.03 seconds
admin@datacenter1.bostonsite1# show peers
Wed 2019-03-20 15:53:01 UTC
============== ============= =========== ============= ====== ======== ============= =============
Peer Node Interface Destination Vlan Status Hostname Path MTU
============== ============= =========== ============= ====== ======== ============= =============
seattlesite1 datacenter1 mpls1 10.0.128.0 0 up unavailable unavailable
seattlesite1 datacenter1 wan1 1.1.1.128 0 up unavailable unavailable
Any questions let me know.
------------------------------
Adam Morris
Sales Engineer
WA
(206) 617-4999
------------------------------
Original Message:
Sent: 03-20-2019 10:31
From: Alan Wright
Subject: Onramp Lab Exercises: Peer active no routes
Hi Folks,
I've just completed the Section for Multiple WAN links, page 230 on the notes.
However, I have a question.
How is it possible for the peer between 1.1.1.128 and 3.3.3.128 to go active when there are no routes and it is not ARP able.
I can only imagine its due ot the gateway configurations on the network interfaces for wan1.
Looking forward to unconfusing my brain :D
TIA
Alan
#3.2.0
------------------------------
Alan Wright
LEATHERHEAD
+44 (0) 20 7043 6127
------------------------------