lab02-OSPF-CLOS

Task Underlay. OSPF

Set up OSPF in the underlay network to establish IP connectivity between all network devices

• Document the following:

⁠◦ Implementation plan

⁠◦ IP addressing scheme

⁠◦ Network topology diagram

⁠◦ Device configurations (if applied manually or via automation)

• Verify IP reachability between all devices within the OSPF domain

Network diagram

The lab is built using the following role-based device mapping host- linux, leaf - frr, spine - arista

Underlay IP Address Allocation

• Underlay addressing follows the format 10.x.y.z, where:

⁠◦ x = Data Center ID

⁠◦ y = Spine switch ID

⁠◦ z = Sequential host address per leaf connection

• Host addressing uses the 172.16.x.z/24 format, where:

⁠◦ x = Leaf switch ID

⁠◦ z = Sequential host address

⁠◦ Each leaf switch uses .1 as its own IP in the corresponding subnet

• Loopback addressing uses 192.168.a.b/32, where:

⁠◦ a = 1 for spine switches

⁠◦ a = 2 for leaf switches

⁠◦ b = Spine or leaf ID (assigned sequentially)

• IPv6 addressing uses fd00::[IPv4]

Interconnect ipv4 ipv6

Device A

Interface A

IPv4 A

IPv6 A

Device B

Interface B

IPv4 B

IPv6 B

Spine-1

Eth1

10.1.1.0/31

fd00::10:1:1:0/127

Leaf-1

Eth8

10.1.1.1/31

fd00::10:1:1:1/127

Spine-1

Eth2

10.1.1.2/31

fd00::10:1:1:2/127

Leaf-2

Eth8

10.1.1.3/31

fd00::10:1:1:3/127

Spine-1

Eth3

10.1.1.4/31

fd00::10:1:1:4/127

Leaf-3

Eth8

10.1.1.5/31

fd00::10:1:1:5/127

Spine-2

Eth2

10.1.2.0/31

fd00::10:2:1:0/127

Leaf-1

Eth9

10.1.2.1/31

fd00::10:2:1:1/127

Spine-2

Eth2

10.1.2.2/31

fd00::10:2:1:2/127

Leaf-2

Eth9

10.1.2.3/31

fd00::10:2:1:3/127

Spine-2

Eth3

10.1.2.4/31

fd00::10:2:1:4/127

Leaf-3

Eth9

10.1.2.5/31

fd00::10:2:1:5/127

Host-1

Eth1

172.16.1.2/24

fd00::172:16:1:2/116

Leaf-1

Eth1

172.16.1.1/24

fd00::172:16:1:1/116

Host-2

Eth1

172.16.2.2/24

fd00::172:16:2:2/116

Leaf-2

Eth1

172.16.2.1/24

fd00::172:16:2:1/116

Host-3

Eth1

172.16.3.2/24

fd00::172:16:3:2/116

Leaf-3

Eth1

172.16.3.1/24

fd00::172:16:3:1/116

Host-4

Eth1

172.16.4.2/24

fd00::172:16:4:2/116

Leaf-3

Eth2

172.16.4.1/24

fd00::172:16:4:1/116

loopback

Device

Loopback ipv4

loopback ipv6

Spine-1

192.168.1.1

fd00::192:168:1:1

Spine-2

192.168.1.2

fd00::192:168:1:2

Leaf-1

192.168.2.1

fd00::192:168:2:1

Leaf-2

192.168.2.2

fd00::192:168:2:2

Leaf-3

192.168.2.2

fd00::192:168:2:3

Since task doesn't contain instructions for host IP addressing, and both leaf and spine nodes are implemented as routers, host IPs are assigned from separate subnets prior to overlay configuration. This ensures basic connectivity while keeping underlay and overlay roles clearly separated.

Once the overlay is deployed, we’ll place all hosts into a single subnet to emulate Layer 2 connectivity.

Launching a lab in the Netlab

Netlab Usage Notes:

To enable BFD in FRR, you need to manually activate the daemon in the default image, since Netlab does not officially declare BFD support for FRR devices. Edit the following file: /usr/local/lib/python3.10/dist-packages/netsim/templates/provider/clab/frr/daemons.j2 and add: bfdd=yes

Similarly, if you want to use other protocols without declaring Netlab modules, you can enable the desired daemons directly in the same file.

Lab Notes:

For OSPF, enable authentication on leaf–spine links using clear-text passwords (spine1, spine2).

Clear-text is used because Netlab does not support MD5 authentication for FRR. Since authentication here serves mainly as a safeguard against misconfiguration, using plain text is acceptable.

Enable BFD on interfaces.

While the timers may appear overly conservative, in practice it's best to avoid values below 500 ms on virtual devices. This ensures stability without compromising responsiveness.

File Topology For quick reference, here’s the inline listing:

topology.yml

---
provider: clab
module: [ ospf ]

nodes:
s1:
device: eos
id: 1
loopback:
  ipv4: 192.168.1.1/32
  ipv6: fd00::192:168:1:1/128
s2:
device: eos
id: 2
loopback:
  ipv4: 192.168.1.2/32
  ipv6: fd00::192:168:1:2/128
l1:
device: frr
id: 3
loopback:
  ipv4: 192.168.2.1/32
  ipv6: fd00::192:168:2:1/128
l2:
device: frr
id: 4
loopback:
  ipv4: 192.168.2.2/32
  ipv6: fd00::192:168:2:2/128
l3:
device: frr
id: 5
loopback:
  ipv4: 192.168.2.3/32
  ipv6: fd00::192:168:2:3/128
h1:
device: linux
h2:
device: linux
h3:
device: linux
h4:
device: linux

links:
#spine1-leaf1,2,3
- interfaces:
    - node: s1
      ifname: eth1
      ipv4: 10.1.1.0
      ipv6: fd00::10:1:1:0
      ospf:
        password: 'spine1'
        bfd: true
    - node: l1
      ifname: eth8
      ipv4: 10.1.1.1
      ipv6: fd00::10:1:1:1
      ospf:
        password: 'spine1'
        bfd: true
  prefix:
    ipv4: 10.1.1.0/31
    ipv6: fd00::10:1:1:0/127
- interfaces:
    - node: s1
      ifname: eth2
      ipv4: 10.1.1.2
      ipv6: fd00::10:1:1:2
      ospf:
        password: 'spine1'
        bfd: true
    - node: l2
      ifname: eth8
      ipv4: 10.1.1.3
      ipv6: fd00::10:1:1:3
      ospf:
        password: 'spine1'
        bfd: true
  prefix:
    ipv4: 10.1.1.2/31
    ipv6: fd00::10:1:1:2/127
- interfaces:
    - node: s1
      ifname: eth3
      ipv4: 10.1.1.4
      ipv6: fd00::10:1:1:4
      ospf:
        password: 'spine1'
        bfd: true
    - node: l3
      ifname: eth8
      ipv4: 10.1.1.5
      ipv6: fd00::10:1:1:5
      ospf:
        password: 'spine1'
        bfd: true
  prefix:
    ipv4: 10.1.1.4/31
    ipv6: fd00::10:1:1:4/127
#spine2-leaf1,2,3
- interfaces:
    - node: s2
      ifname: eth1
      ipv4: 10.1.2.0
      ipv6: fd00::10:1:2:0
      ospf:
        password: 'spine2'
        bfd: true
    - node: l1
      ifname: eth9
      ipv4: 10.1.2.1
      ipv6: fd00::10:1:2:1
      ospf:
        password: 'spine2'
        bfd: true
  prefix:
    ipv4: 10.1.2.0/31
    ipv6: fd00::10:1:2:0/127
- interfaces:
    - node: s2
      ifname: eth2
      ipv4: 10.1.2.2
      ipv6: fd00::10:1:2:2
      ospf:
        password: 'spine2'
        bfd: true
    - node: l2
      ifname: eth9
      ipv4: 10.1.2.3
      ipv6: fd00::10:1:2:3
      ospf:
        password: 'spine2'
        bfd: true
  prefix:
    ipv4: 10.1.2.2/31
    ipv6: fd00::10:1:2:2/127
- interfaces:
    - node: s2
      ifname: eth3
      ipv4: 10.1.2.4
      ipv6: fd00::10:1:2:4
      ospf:
        password: 'spine2'
        bfd: true
    - node: l3
      ifname: eth9
      ipv4: 10.1.2.5
      ipv6: fd00::10:1:2:5
      ospf:
        password: 'spine2'
        bfd: true
  prefix:
    ipv4: 10.1.2.4/31
    ipv6: fd00::10:1:2:4/127
#host1
- interfaces:
    - node: h1
      ifname: eth1
      ipv4: 172.16.1.2
      ipv6: fd00::172:16:1:2
    - node: l1
      ifname: eth1
      ipv4: 172.16.1.1
      ipv6: fd00::172:16:1:1
      ospf: false
  prefix:
    ipv4: 172.16.1.0/24
    ipv6: fd00::172:16:1:0/116
#host2
- interfaces:
    - node: h2
      ifname: eth1
      ipv4: 172.16.2.2
      ipv6: fd00::172:16:2:2
    - node: l2
      ifname: eth1
      ipv4: 172.16.2.1
      ipv6: fd00::172:16:2:1
      ospf: false
  prefix:
    ipv4: 172.16.2.0/24
    ipv6: fd00::172:16:1:0/116
#host3
- interfaces:
    - node: h3
      ifname: eth1
      ipv4: 172.16.3.2
      ipv6: fd00::172:16:3:2
    - node: l3
      ifname: eth1
      ipv4: 172.16.3.1
      ipv6: fd00::172:16:3:1
      ospf: false
  prefix:
    ipv4: 172.16.3.0/24
    ipv6: fd00::172:16:3:0/116
#host4
- interfaces:
    - node: h4
      ifname: eth1
      ipv4: 172.16.4.2
      ipv6: fd00::172:16:4:2
    - node: l3
      ifname: eth2
      ipv4: 172.16.4.1
      ipv6: fd00::172:16:4:1
      ospf: false
  prefix:
    ipv4: 172.16.4.0/24
    ipv6: fd00::172:16:4:0/116

Validating

spine-1

s1#show ip ro

VRF: default

Gateway of last resort is not set

C        10.1.1.0/31
         directly connected, Ethernet1
C        10.1.1.2/31
         directly connected, Ethernet2
C        10.1.1.4/31
         directly connected, Ethernet3
O        10.1.2.0/31 [110/20]
         via 10.1.1.1, Ethernet1
O        10.1.2.2/31 [110/20]
         via 10.1.1.3, Ethernet2
O        10.1.2.4/31 [110/20]
         via 10.1.1.5, Ethernet3
C        192.168.1.1/32
         directly connected, Loopback0
O        192.168.1.2/32 [110/30]
         via 10.1.1.1, Ethernet1
         via 10.1.1.3, Ethernet2
         via 10.1.1.5, Ethernet3
O        192.168.2.1/32 [110/10]
         via 10.1.1.1, Ethernet1
O        192.168.2.2/32 [110/10]
         via 10.1.1.3, Ethernet2
O        192.168.2.3/32 [110/10]
         via 10.1.1.5, Ethernet3

s1#show ipv6 ro

VRF: default

O3       fd00::10:1:1:1/128 [110/10]
         via fe80::a8c1:abff:fe9a:849, Ethernet1
C        fd00::10:1:1:0/127 [0/0]
         via Ethernet1, directly connected
O3       fd00::10:1:1:3/128 [110/10]
         via fe80::a8c1:abff:fef1:7cc4, Ethernet2
C        fd00::10:1:1:2/127 [0/0]
         via Ethernet2, directly connected
O3       fd00::10:1:1:5/128 [110/10]
         via fe80::a8c1:abff:feef:e7a2, Ethernet3
C        fd00::10:1:1:4/127 [0/0]
         via Ethernet3, directly connected
O3       fd00::10:1:2:1/128 [110/10]
         via fe80::a8c1:abff:fe9a:849, Ethernet1
O3       fd00::10:1:2:0/127 [110/20]
         via fe80::a8c1:abff:fe9a:849, Ethernet1
O3       fd00::10:1:2:3/128 [110/10]
         via fe80::a8c1:abff:fef1:7cc4, Ethernet2
O3       fd00::10:1:2:2/127 [110/20]
         via fe80::a8c1:abff:fef1:7cc4, Ethernet2
O3       fd00::10:1:2:5/128 [110/10]
         via fe80::a8c1:abff:feef:e7a2, Ethernet3
O3       fd00::10:1:2:4/127 [110/20]
         via fe80::a8c1:abff:feef:e7a2, Ethernet3
C        fd00::192:168:1:1/128 [0/0]
         via Loopback0, directly connected
O3       fd00::192:168:1:2/128 [110/30]
         via fe80::a8c1:abff:fe9a:849, Ethernet1
         via fe80::a8c1:abff:fef1:7cc4, Ethernet2
         via fe80::a8c1:abff:feef:e7a2, Ethernet3
O3       fd00::192:168:2:1/128 [110/10]
         via fe80::a8c1:abff:fe9a:849, Ethernet1
O3       fd00::192:168:2:2/128 [110/10]
         via fe80::a8c1:abff:fef1:7cc4, Ethernet2
O3       fd00::192:168:2:3/128 [110/10]
         via fe80::a8c1:abff:feef:e7a2, Ethernet3

s1#show bfd peers
VRF name: default
-----------------
DstAddr               MyDisc         YourDisc       Interface/Transport         Type               LastUp       LastDown            LastDiag    State
-------------- ---------------- ---------------- ------------------------- ------------ -------------------- -------------- ------------------- -----
10.1.1.1          4036363286       3063445977           Ethernet1(1129)       normal       08/20/25 22:21             NA       No Diagnostic       Up
10.1.1.3          1231824312       1715554816           Ethernet2(1131)       normal       08/20/25 22:21             NA       No Diagnostic       Up
10.1.1.5          2599637788       1867128317           Ethernet3(1133)       normal       08/20/25 22:21             NA       No Diagnostic       Up

DstAddr                                MyDisc        YourDisc       Interface/Transport         Type               LastUp       LastDown            LastDiag    State
------------------------------- ---------------- --------------- ------------------------- ------------ -------------------- -------------- ------------------- -----
fe80::a8c1:abff:fe9a:849           4221965281       365649942           Ethernet1(1129)       normal       08/20/25 22:21             NA       No Diagnostic       Up
fe80::a8c1:abff:feef:e7a2          1006718991       365649942           Ethernet3(1133)       normal       08/20/25 22:21             NA       No Diagnostic       Up
fe80::a8c1:abff:fef1:7cc4           216279368       503132544           Ethernet2(1131)       normal       08/20/25 22:21             NA       No Diagnostic       Up

spine-2

s2#show ip ro

VRF: default


Gateway of last resort is not set

O        10.1.1.0/31 [110/20]
         via 10.1.2.1, Ethernet1
O        10.1.1.2/31 [110/20]
         via 10.1.2.3, Ethernet2
O        10.1.1.4/31 [110/20]
         via 10.1.2.5, Ethernet3
C        10.1.2.0/31
         directly connected, Ethernet1
C        10.1.2.2/31
         directly connected, Ethernet2
C        10.1.2.4/31
         directly connected, Ethernet3
O        192.168.1.1/32 [110/30]
         via 10.1.2.1, Ethernet1
         via 10.1.2.3, Ethernet2
         via 10.1.2.5, Ethernet3
C        192.168.1.2/32
         directly connected, Loopback0
O        192.168.2.1/32 [110/10]
         via 10.1.2.1, Ethernet1
O        192.168.2.2/32 [110/10]
         via 10.1.2.3, Ethernet2
O        192.168.2.3/32 [110/10]
         via 10.1.2.5, Ethernet3

s2#show ipv6 ro

VRF: default
Displaying 17 of 23 IPv6 routing table entries

O3       fd00::10:1:1:1/128 [110/10]
         via fe80::a8c1:abff:fe45:5487, Ethernet1
O3       fd00::10:1:1:0/127 [110/20]
         via fe80::a8c1:abff:fe45:5487, Ethernet1
O3       fd00::10:1:1:3/128 [110/10]
         via fe80::a8c1:abff:feab:149e, Ethernet2
O3       fd00::10:1:1:2/127 [110/20]
         via fe80::a8c1:abff:feab:149e, Ethernet2
O3       fd00::10:1:1:5/128 [110/10]
         via fe80::a8c1:abff:fe2a:bc56, Ethernet3
O3       fd00::10:1:1:4/127 [110/20]
         via fe80::a8c1:abff:fe2a:bc56, Ethernet3
O3       fd00::10:1:2:1/128 [110/10]
         via fe80::a8c1:abff:fe45:5487, Ethernet1
C        fd00::10:1:2:0/127 [0/0]
         via Ethernet1, directly connected
O3       fd00::10:1:2:3/128 [110/10]
         via fe80::a8c1:abff:feab:149e, Ethernet2
C        fd00::10:1:2:2/127 [0/0]
         via Ethernet2, directly connected
O3       fd00::10:1:2:5/128 [110/10]
         via fe80::a8c1:abff:fe2a:bc56, Ethernet3
C        fd00::10:1:2:4/127 [0/0]
         via Ethernet3, directly connected
O3       fd00::192:168:1:1/128 [110/30]
         via fe80::a8c1:abff:fe45:5487, Ethernet1
         via fe80::a8c1:abff:feab:149e, Ethernet2
         via fe80::a8c1:abff:fe2a:bc56, Ethernet3
C        fd00::192:168:1:2/128 [0/0]
         via Loopback0, directly connected
O3       fd00::192:168:2:1/128 [110/10]
         via fe80::a8c1:abff:fe45:5487, Ethernet1
O3       fd00::192:168:2:2/128 [110/10]
         via fe80::a8c1:abff:feab:149e, Ethernet2
O3       fd00::192:168:2:3/128 [110/10]
         via fe80::a8c1:abff:fe2a:bc56, Ethernet3

s2#show bfd peers
VRF name: default
-----------------
DstAddr               MyDisc         YourDisc       Interface/Transport         Type               LastUp       LastDown            LastDiag    State
-------------- ---------------- ---------------- ------------------------- ------------ -------------------- -------------- ------------------- -----
10.1.2.1          1038882734       1867128317           Ethernet1(1140)       normal       08/20/25 22:21             NA       No Diagnostic       Up
10.1.2.3           476357661       2044274492           Ethernet2(1144)       normal       08/20/25 22:21             NA       No Diagnostic       Up
10.1.2.5          2107959149       3063445977           Ethernet3(1146)       normal       08/20/25 22:21             NA       No Diagnostic       Up

DstAddr                                MyDisc         YourDisc       Interface/Transport         Type               LastUp       LastDown            LastDiag    State
------------------------------- ---------------- ---------------- ------------------------- ------------ -------------------- -------------- ------------------- -----
fe80::a8c1:abff:fe2a:bc56           755184907       3120229879           Ethernet3(1146)       normal       08/20/25 22:21             NA       No Diagnostic       Up
fe80::a8c1:abff:fe45:5487          2205458108       3120229879           Ethernet1(1140)       normal       08/20/25 22:21             NA       No Diagnostic       Up
fe80::a8c1:abff:feab:149e          1370192998       1612082641           Ethernet2(1144)       normal       08/20/25 22:21             NA       No Diagnostic       Up

Verify ping reachability to all device loopbacks from leaf-1.

leaf-1 pings

l1# ping 192.168.2.2
PING 192.168.2.2 (192.168.2.2): 56 data bytes
64 bytes from 192.168.2.2: seq=0 ttl=63 time=0.813 ms
64 bytes from 192.168.2.2: seq=1 ttl=63 time=0.961 ms
64 bytes from 192.168.2.2: seq=2 ttl=63 time=0.964 ms
64 bytes from 192.168.2.2: seq=3 ttl=63 time=0.932 ms
^C
--- 192.168.2.2 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 0.813/0.917/0.964 ms
l1# ping 192.168.2.3
PING 192.168.2.3 (192.168.2.3): 56 data bytes
64 bytes from 192.168.2.3: seq=0 ttl=63 time=1.186 ms
64 bytes from 192.168.2.3: seq=1 ttl=63 time=1.043 ms
64 bytes from 192.168.2.3: seq=2 ttl=63 time=1.222 ms
64 bytes from 192.168.2.3: seq=3 ttl=63 time=1.048 ms
^C
--- 192.168.2.3 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 1.043/1.124/1.222 ms
l1# ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1): 56 data bytes
64 bytes from 192.168.1.1: seq=0 ttl=64 time=0.145 ms
64 bytes from 192.168.1.1: seq=1 ttl=64 time=0.118 ms
64 bytes from 192.168.1.1: seq=2 ttl=64 time=0.099 ms
64 bytes from 192.168.1.1: seq=3 ttl=64 time=0.098 ms
^C
--- 192.168.1.1 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 0.098/0.115/0.145 ms
l1# ping 192.168.1.2
PING 192.168.1.2 (192.168.1.2): 56 data bytes
64 bytes from 192.168.1.2: seq=0 ttl=64 time=0.102 ms
64 bytes from 192.168.1.2: seq=1 ttl=64 time=0.101 ms
64 bytes from 192.168.1.2: seq=2 ttl=64 time=0.101 ms
64 bytes from 192.168.1.2: seq=3 ttl=64 time=0.112 ms
^C
--- 192.168.1.2 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 0.101/0.104/0.112 ms
l1# ping ipv6 fd00::192:168:2:2
PING fd00::192:168:2:2 (fd00::192:168:2:2): 56 data bytes
64 bytes from fd00::192:168:2:2: seq=0 ttl=63 time=1.543 ms
64 bytes from fd00::192:168:2:2: seq=1 ttl=63 time=0.781 ms
64 bytes from fd00::192:168:2:2: seq=2 ttl=63 time=1.588 ms
^C
--- fd00::192:168:2:2 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.781/1.304/1.588 ms
l1# ping ipv6 fd00::192:168:2:3
PING fd00::192:168:2:3 (fd00::192:168:2:3): 56 data bytes
64 bytes from fd00::192:168:2:3: seq=0 ttl=63 time=1.360 ms
64 bytes from fd00::192:168:2:3: seq=1 ttl=63 time=0.760 ms
64 bytes from fd00::192:168:2:3: seq=2 ttl=63 time=0.913 ms
^C
--- fd00::192:168:2:3 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.760/1.011/1.360 ms
l1# ping ipv6 fd00::192:168:1:1
PING fd00::192:168:1:1 (fd00::192:168:1:1): 56 data bytes
64 bytes from fd00::192:168:1:1: seq=0 ttl=64 time=0.096 ms
64 bytes from fd00::192:168:1:1: seq=1 ttl=64 time=0.149 ms
64 bytes from fd00::192:168:1:1: seq=2 ttl=64 time=0.101 ms
^C
--- fd00::192:168:1:1 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.096/0.115/0.149 ms
l1# ping ipv6 fd00::192:168:1:2
PING fd00::192:168:1:2 (fd00::192:168:1:2): 56 data bytes
64 bytes from fd00::192:168:1:2: seq=0 ttl=64 time=0.111 ms
64 bytes from fd00::192:168:1:2: seq=1 ttl=64 time=0.128 ms
64 bytes from fd00::192:168:1:2: seq=2 ttl=64 time=0.116 ms
64 bytes from fd00::192:168:1:2: seq=3 ttl=64 time=0.097 ms
^C
--- fd00::192:168:1:2 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 0.097/0.113/0.128 ms

Device configuration files: Spine-1 Spine-2 Leaf-1 Leaf-2 Leaf-3

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