This example shows a Fabric Extend deployment with 1 Gbps switches in the core of the network and in the branch sites. This type of deployment is not only a lower cost Fabric Extend solution, it also addresses situations where large MTU sizes (over 1594 bytes) are a problem for the Service Provider.
MTU sizes less than 1594 bytes require fragmentation and reassembly of packets and the 1 Gbps switch with ONA supports fragmentation and reassembly. However, you must have 1 Gbps switches with ONAs at BOTH ends of the IP WAN connection.
Important
There is no fragmentation/reassembly support in Layer 2 core solutions.
The following figure shows a sample Fabric Extend deployment using VRFs with both switches.
(The tunnel source address is a CLIP address on the VRF. This address is configured on the switch and then automatically assigned to the ONA.)
Switch(config)# ip vrf vrf24 Switch(config)# router vrf vrf24 Switch(router-vrf)# ip ospf Switch(router-vrf)# ip ospf admin-state Switch(router-vrf)# exit Switch(config)# interface loopback 256 Switch(config-if)# ip address 197.1.5.2 255.255.255.255 vrf vrf24 Switch(config-if)# ip ospf vrf vrf24 Switch(config-if)# exit Switch(config)# interface GigabitEthernet 1/7-1/8; enables ports to ONA Switch(config-if)# no shutdown Switch(config-if)# exit Switch(config)# vlan create 3036 name "ospf-intf-SP-core" type port-mstprstp 0 Switch(config)# vlan members 3036 1/14 portmember Switch(config)# interface vlan 3036 Switch(config)# vrf vrf24 Switch(config-if)# ip address 197.1.1.2 255.255.255.0 0 Switch(config-if)# ip ospf enable Switch(config-if)# exit Switch(config)# vlan create 3024 name "ONA-Mgmt-vlan" type port-mstprstp 0 Switch(config)# vlan members 3024 1/8 portmember Switch(config)# interface vlan 3024 Switch(config-if)# ip address 197.3.1.1 255.255.255.0 3 Switch(config-if)# exit Switch(config)# ip dhcp-relay fwd-path 197.3.1.1 197.10.1.11 Switch(config)# ip dhcp-relay fwd-path 197.3.1.1 197.10.1.11 enable Switch(config)# ip dhcp-relay fwd-path 197.3.1.1 197.10.1.11 mode bootp_dhcp Switch(config)# router isis Switch(config-isis)# ip-tunnel-source-address 197.1.5.2 port 1/7 vrf vrf24 mtu 1950 Switch(config-isis)# exit Switch(config)# logical-intf isis 255 dest-ip 197.1.6.2 name "Tunnel-to-Branch1" Switch(config-isis-255-197.1.6.2)# isis Switch(config-isis-255-197.1.6.2)# isis spbm 1 Switch(config-isis-255-197.1.6.2)# isis enable Switch(config-isis-255-197.2.1.1)# exit
(The tunnel source address is a CLIP address on the VRF. This address is configured on the switch and then automatically assigned to the ONA.)
Switch(config)# ip vrf vrf24 Switch(config)# router vrf vrf24 Switch(router-vrf)# ip ospf Switch(router-vrf)# ip ospf admin-state Switch(router-vrf)# exit Switch(config)# interface loopback 256 Switch(config-if)# ip address 197.1.6.2 255.255.255.255 vrf vrf24 Switch(config-if)# ip ospf vrf vrf24 Switch(config-if)# exit Switch(config)# interface GigabitEthernet 1/7-1/8; enables ports to ONA Switch(config-if)# no shutdown Switch(config-if)# exit Switch(config)# vlan create 3037 name "ospf-intf-SP-core" type port-mstprstp 0 Switch(config)# vlan members 3037 1/49-1/50 portmember Switch(config)# interface vlan 3037 Switch(config-if)# vrf vrf24 Switch(config-if)# ip address 197.1.11.2 255.255.255.0 0 Switch(config-if)# ip ospf enable Switch(config-if)# exit Switch(config)# vlan create 3025 name "ONA-Mgmt-vlan" type port-mstprstp 0 Switch(config)# vlan members 3025 1/8 portmember Switch(config)# interface vlan 3025 Switch(config-if)# ip address 197.2.1.1 255.255.255.0 3 Switch(config-if)# exit Switch(config)# ip dhcp-relay fwd-path 197.2.1.1 197.10.1.11 Switch(config)# ip dhcp-relay fwd-path 197.2.1.1 197.10.1.11 enable Switch(config)# ip dhcp-relay fwd-path 197.2.1.1 197.10.1.11 mode bootp_dhcp Switch(config)# router isis Switch(config-isis)# ip-tunnel-source-address 197.1.6.2 port 1/7 vrf vrf24 mtu 1950 Switch(config-isis)# exit Switch(config)# logical-intf isis 255 dest-ip 197.1.5.2 name "Tunnel-to-HQ" Switch(config-isis-255-197.1.1.2)# isis Switch(config-isis-255-197.1.1.2)# isis spbm 1 Switch(config-isis-255-197.1.1.2)# isis enable Switch(config-isis-255-197.1.1.2)# exit
Intermediate routers are typically configured by an Internet service provider (ISP). The following configurations are for reference only.
Switch(config)# interface GigabitEthernet 8/19 Switch(config-if)# default-vlan-id 0 Switch(config-if)# name "ospf-intf-from-Headoffice" Switch(config-if)# no shutdown Switch(config-if)# brouter port 8/19 vlan 3036 subnet 197.1.1.3/255.255.255.0 mac-offset 2 Switch(config-if)# ip ospf enable Switch(config-if)# exit Switch(config)# vlan create 3039 name "core-ospf-vlan" type port-mstprstp 0 Switch(config)# vlan members 3039 8/1 portmember Switch(config)# interface Vlan 3039 Switch(config)# ip address 197.1.8.1 255.255.255.0 2 Switch(config)# ip ospf enable Switch(config)# exit
Switch(config)# vlan create 3039 name "core-ospf-vlan" type port-mstprstp 0 Switch(config)# vlan members 3039 8/1 portmember Switch(config)# interface Vlan 3039 Switch(config)# ip address 197.1.8.2 255.255.255.0 0 Switch(config)# ip ospf enable Switch(config)# exit Switch(config)# vlan create 3037 name "ospf-intf-from-branch1" type port-mstprstp 0 Switch(config)# vlan members 3037 8/21-8/22 portmember Switch(config)# mlt 11 Switch(config)# mlt 11 encapsulation dot1q Switch(config)# mlt 11 mem 8/21-8/22 Switch(config)# mlt 11 vlan 3037 Switch(config)# interface Vlan 3037 Switch(config)# ip address 197.1.11.1 255.255.255.0 5 Switch(config)# ip ospf enable Switch(config)# exit