Administrator Guide

R1#show run | find router
router ospf 1
router-id 172.15.1.1
passive-interface default
no passive-interface Port-channel1
network 2.2.2.0 0.0.0.255 area 0
network 3.3.3.0 0.0.0.255 area 0
network 4.4.4.0 0.0.0.255 area 0
(The above subnets correspond to loopback interfaces lo2, lo3 and lo4. These three loopback
interfaces are advertised to the VLT pair, DellEMC#1 and DellEMC#2)
network 172.15.1.0 0.0.0.255 area 0
network 192.168.20.0 0.0.0.7 area 0
CR1#show ip ospf neighbor
(R1 is a DROTHER)
Neighbor ID Pri State Dead Time Address Interface
172.16.1.2 1 FULL/BDR 00:00:31 192.168.20.2 Port-channel1
172.17.1.1 1 FULL/DR 00:00:38 192.168.20.1 Port-channel1
CR1#show ip route
(Output Truncated)
2.0.0.0/24 is subnetted, 1 subnets
C 2.2.2.0 is directly connected, Loopback2
3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback3
O 192.168.8.0/24 [110/2] via 192.168.20.2, 02:02:34, Port-channel1
[110/2] via 192.168.20.1, 02:02:34, Port-channel1
(OSPF-learned route back to client subnet – VLAN 800)
4.0.0.0/24 is subnetted, 1 subnets
C 4.4.4.0 is directly connected, Loopback4
O 192.168.9.0/24 [110/2] via 192.168.20.2, 02:02:34, Port-channel1
[110/2] via 192.168.20.1, 02:02:34, Port-channel1
(OSPF-learned route back to client subnet #2 – VLAN 900)
172.17.0.0/24 is subnetted, 1 subnets
O 172.17.1.1 [110/1] via 192.168.20.1, 02:02:34, Port-channel1
172.16.0.0/24 is subnetted, 1 subnets
O 172.16.1.2 [110/1] via 192.168.20.2, 02:02:34, Port-channel1
192.168.20.0/29 is subnetted, 1 subnets
C 192.168.20.0 is directly connected, Port-channel1
(OSPF peering VLAN)
10.0.0.0/24 is subnetted, 1 subnets
C 10.10.10.0 is directly connected, FastEthernet0/2
Access Switch A1 Configurations and Verification
A1 access switch is configured to not be the STP root bridge
A1#sh run | be spanning
spanning-tree mode pvst
spanning-tree vlan 1,800,900 priority 61440
interface Port-channeL2
description Port-Channel_to_Dell_VLT_Te0/4
switchport trunk encapsulation dot1q
switchport mode trunk
spanning-tree portfast trunk
This default route is configured for testing purposes, as described in the next section. The access switch (A1) is used to generate ICMP
test PINGs to a loopback interface on CR1. This default route points to DellEMC#2’s VLAN 800 SVI interface. It’s in place to ensure that
routed test traffic has DellEMC#2’s MAC address as the destination address in the Ethernet frame’s header
When A1 sends a packet to R1, the VLT peers act as the default gateway for each other. If the packet reaches Dell-1, irrespective of the
default gateway used, Dell-1 routes the packet to R1. Similarly, if the packet reaches Dell-2, irrespective of the default gateway used,
Dell-2 routes the packet to R1.
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Virtual Link Trunking (VLT)