Spine and Leaf Practical Applications, OSPF
As covered in the previous post, base configuration of a spine-and-leaf fabric is actually pretty simple. This will be pretty short, but we'll cover the conversion of the previously built fabric to OSPF.
Here's the updated diagram: (YAML). As we move to a more full-fledged implementation, we'll do dual-stack.
The cleanup for this is as follows:
1no router rip
From here, we can configure the router statements on all devices. It can be the same for all, because of the summarization performed while planning out the network.
1router ospf 1
2 ispf
3 log-adjacency-changes
4 nsf cisco
5 network 10.6.0.0 0.0.0.255 area 0
6 network 10.6.240.0 0.0.1.255 area 0
In a production environment you should add passive-interface default on the leafs if the ToR does not peer dynamic routing with anything sub-tending it.
Unsurprisingly, this just works. Now, to setup IPv6!
1ospf-s0#conf t
2Enter configuration commands, one per line. End with CNTL/Z.
3ospf-s0(config)#ipv6?
4% Unrecognized command
Well, it looks like IPv6 is not available until IOS 12.2.55. Let's use this network to upgrade it, by hooking up a TFTP server to leaf-1:
1
2interface FastEthernet0/14
3 no switchport
4 ip address 10.66.0.1 255.255.255.0
5!
6router ospf 1
7 network 10.66.0.1 0.0.0.0 area 0
We test reachability from the other leaf - this is a fully layer 3 switched path:
1ospf-l0#ping 10.66.0.180
2
3Type escape sequence to abort.
4Sending 5, 100-byte ICMP Echos to 10.66.0.180, timeout is 2 seconds:
5!!!!!
6Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/8 ms
And then we copy it over TFTP:
1ospf-s1#copy tftp flash:
2Address or name of remote host []? 10.66.0.180
3Source filename []? c3560-ipservicesk9-mz.122-55.SE6.bin
4Destination filename [c3560-ipservicesk9-mz.122-55.SE6.bin]?
5Accessing tftp://10.66.0.180/c3560-ipservicesk9-mz.122-55.SE6.bin...
6Loading c3560-ipservicesk9-mz.
7[OK - 12752912 bytes]
8
912752912 bytes copied in 201.133 secs (63405 bytes/sec)
Note that this, while a practical application, is still non-redundant.
UPGRADING INTENSIFIES
Now to implement IPv6 as follows: (YAML)
Note: We used ; instead of : due to a feature issue with drawthe.net. We're using /126 prefixes because this is on older equipment, which may not support /127 prefixes reliably.
On all devices, we need to enable ipv6 routing / OSPFv3:
1ipv6 unicast-routing
2ipv6 router ospf 2
3 log-adjacency-changes
We then configure each device:
1ospf-l0# configure terminal
2interface Loopback0
3 ip address 10.6.0.0 255.255.255.255
4 ipv6 address FD00:6::/128
5 ipv6 ospf 2 area 0
6interface FastEthernet1/0/21
7 no switchport
8 ip address 10.6.241.1 255.255.255.254
9 ipv6 address FD00:6:241::2/126
10 ipv6 enable
11 ipv6 ospf 2 area 0
12interface FastEthernet1/0/24
13 no switchport
14 ip address 10.6.240.1 255.255.255.254
15 ipv6 address FD00:6:240::2/126
16 ipv6 enable
17 ipv6 ospf 2 area 0
18
19ospf-l1# configure terminal
20interface Loopback0
21 ip address 10.6.0.1 255.255.255.255
22 ipv6 address FD00:6::1/128
23 ipv6 ospf 2 area 0
24interface FastEthernet0/22
25 no switchport
26 ip address 10.6.240.3 255.255.255.254
27 ipv6 address FD00:6:240::6/126
28 ipv6 enable
29 ipv6 ospf 2 area 0
30interface FastEthernet0/23
31 no switchport
32 ip address 10.6.241.3 255.255.255.254
33 ipv6 address FD00:6:241::6/126
34 ipv6 enable
35 ipv6 ospf 2 area 0
36
37ospf-s0# configure terminal
38interface Loopback0
39 ip address 10.6.0.240 255.255.255.255
40 ipv6 address FD00:6::240/128
41 ipv6 ospf 2 area 0
42interface FastEthernet0/22
43 no switchport
44 ip address 10.6.240.2 255.255.255.254
45 ipv6 address FD00:6:241::1/126
46 ipv6 enable
47 ipv6 ospf 2 area 0
48interface FastEthernet0/24
49 no switchport
50 ip address 10.6.240.0 255.255.255.254
51 ipv6 address FD00:6:240::1/126
52 ipv6 enable
53 ipv6 ospf 2 area 0
54
55ospf-s1# configure terminal
56interface Loopback0
57 ip address 10.6.0.241 255.255.255.255
58 ipv6 address FD00:6::241/128
59 ipv6 ospf 2 area 0
60interface FastEthernet0/21
61 no switchport
62 ip address 10.6.241.0 255.255.255.254
63 ipv6 address FD00:6:241::1/126
64 ipv6 enable
65 ipv6 ospf 2 area 0
66interface FastEthernet0/23
67 no switchport
68 ip address 10.6.241.2 255.255.255.254
69 ipv6 address FD00:6:241::5/126
70 ipv6 enable
71 ipv6 ospf 2 area 0
From here, we test by initiating traffic from a subtending network on Leaf-1 to Leaf-0, and checking the routing tables:
1ospf-l1#ping ipv6 fd00:6::
2
3Type escape sequence to abort.
4Sending 5, 100-byte ICMP Echos to FD00:6::, timeout is 2 seconds:
5!!!!!
6Success rate is 100 percent (5/5), round-trip min/avg/max = 0/1/8 ms
7ospf-l1#show ip route
8Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
9 D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
10 N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
11 E1 - OSPF external type 1, E2 - OSPF external type 2
12 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
13 ia - IS-IS inter area, * - candidate default, U - per-user static route
14 o - ODR, P - periodic downloaded static route
15
16Gateway of last resort is not set
17
18 10.0.0.0/8 is variably subnetted, 8 subnets, 2 masks
19O 10.6.0.0/32 [110/3] via 10.6.241.2, 00:03:58, FastEthernet0/23
20 [110/3] via 10.6.240.2, 00:03:58, FastEthernet0/22
21C 10.6.0.1/32 is directly connected, Loopback0
22O 10.6.240.0/31 [110/2] via 10.6.240.2, 00:03:58, FastEthernet0/22
23O 10.6.0.240/32 [110/2] via 10.6.240.2, 00:03:58, FastEthernet0/22
24O 10.6.241.0/31 [110/2] via 10.6.241.2, 00:03:58, FastEthernet0/23
25O 10.6.0.241/32 [110/2] via 10.6.241.2, 00:03:58, FastEthernet0/23
26C 10.6.240.2/31 is directly connected, FastEthernet0/22
27C 10.6.241.2/31 is directly connected, FastEthernet0/23
28ospf-l1#show ipv6 route
29IPv6 Routing Table - Default - 11 entries
30Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
31 B - BGP, R - RIP, D - EIGRP, EX - EIGRP external
32 ND - Neighbor Discovery
33 O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
34 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
35O FD00:6::/128 [110/2]
36 via FE80::216:C8FF:FE04:4741, FastEthernet0/22
37 via FE80::223:4FF:FE42:F3C2, FastEthernet0/23
38LC FD00:6::1/128 [0/0]
39 via Loopback0, receive
40O FD00:6::240/128 [110/1]
41 via FE80::216:C8FF:FE04:4741, FastEthernet0/22
42O FD00:6::241/128 [110/1]
43 via FE80::223:4FF:FE42:F3C2, FastEthernet0/23
44O FD00:6:240::/126 [110/2]
45 via FE80::216:C8FF:FE04:4741, FastEthernet0/22
46C FD00:6:240::4/126 [0/0]
47 via FastEthernet0/22, directly connected
48L FD00:6:240::6/128 [0/0]
49 via FastEthernet0/22, receive
50O FD00:6:241::/126 [110/1]
51 via FastEthernet0/22, directly connected
52C FD00:6:241::4/126 [0/0]
53 via FastEthernet0/23, directly connected
54L FD00:6:241::6/128 [0/0]
55 via FastEthernet0/23, receive
56L FF00::/8 [0/0]
57 via Null0, receive
Note: technically we don't have to number the leaf-spine-leaf links in IPv6 with OSPFv3/RIP-ng/EIGRP, but that is a personal preference of mine to keep it consistent with future designs, and to allow for ease of troubleshooting.
As always, example configurations are here.
Posts in this Series
- Spine and Leaf Networks, an Outline
- Spine and Leaf Practical Applications, The IP Portability Problem
- Spine and Leaf Practical Applications, EGP and IGP combined!
- Spine and Leaf Practical Applications, eBGP
- Spine and Leaf Practical Applications, OSPF
- Spine and Leaf Practical Applications, RIPv2
- Spine and Leaf Networks, a Topology
- Spine and Leaf Networks, an Introduction