overview

clos 2 tier topology with 2 spines and 2 leaves

bgp unnumbered.png

there is an 802.3ad lacp lag / bond between leaf1 and leaf2

private asns are used, which is normal in the datacenter, both the spines would have the same asn

unnumbered peering is actually achieved by the readily available link local ipv6 addresses, avoiding the need of explicitly configuring ip addresses on the interfaces

.....

ip addressing

loopback lo: spine1 - 192.168.1.11/32, spine2 - 12/32, leaf1 - 21/32, leaf2 - 22/32

vlan 100: leaf1 - 192.168.100.21/24, leaf2 - 22/24, host1 - 31/24, host2 - 32/24

.....

nclu configuration

example: leaf1

net add hostname leaf1

net add loopback lo ip address 192.168.1.21/32

net add vlan 100 ip address 192.168.100.21/24    #connection to the host

net add interface swp5 bridge access 100

net add bond leaf1_leaf2 bond slaves swp3-4    #name of the bond is leaf1_leaf2

net add bgp autonomous-system 65501
net add bgp router-id 192.168.1.21
net add bgp neighbor swp1-2,leaf1_leaf2 remote-as external    #this is the unnumbered config, no ips, only interfaces

net add bgp network 192.168.1.21/32    #to advertise the loopback

net add bgp network 192.168.100.21/24    #to advertise vlan 100

net commit

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configuration on host

example: host2

cat /etc/network/interfaces

auto eth0
iface eth0 inet static
address 192.168.100.32
netmask 255.255.255.0
gateway 192.168.100.22

.....

verification:

net show bgp {ip}
net show bgp summary
net show bgp neighbor
net show route {ip}
ip neighbor    #169.254.0.1 is reserved for bgp unnumbered

.....

reference

https://cumulusnetworks.com

https://tools.ietf.org/html/rfc5549

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