IVT and multilayer switching is very commonplace in today’s network. SVI can be used to allow inter-VLAN communication on a switch multilayer, eliminating the need for a separate router to get involved.
# Ping 30.1.1.1 HOST_1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 30.1.1.1, timeout is 2 seconds:.....
The success rate is 0 percent (0 / 5)
# Ping 20.1.1.1 HOST_3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 20.1.1.1, timeout is 2 seconds...
The success rate is 0 percent (0 / 5)
As we wait, there’s no IP connectivity between hosts. Assuming that the appropriate switch ports are already placed in VLAN 11 and VLAN 33, well now create two virtual interfaces turned on the switch multilayer. One will represent VLAN 33, and the other representing VLAN 11.
SW1 (config) # int vlan11
1:30:04:% LINK-3-UPDOWN: Interface Vlan11, the state has changed place
1:30:05:% LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan11, the state has changed place
SW1 (config-if) # ip address 20.1.1.11 255.255.255.0
SW1 (config-if) # int vlan33
1:30:11:% LINK-3-UPDOWN: Interface Vlan33, the state has changed place
1:30:12:% LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan33, the state has changed place
SW1 (config-if) # ip address 30.1.1.11 255.255.255.0
At this point, we’ve always had a problem when we look at the routing table.
SW1 # show ip route
the default gateway is not set
Host Gateway Last Use Total use interface
ICMP redirect cache is empty
The problem is that we do not have a routing table, because IP routing is disabled by default on a switch multilayer. Let’s turn on IP routing, then check the routing table.
SW 1 (config) # ip routing
SW1 (config) # ~ Z
SW1 # show ip route
Gateway of last resort is not set
20.0.0.0/24 is subnetted, 1 subnets
C 20.1.1.0 is directly connected, Vlan11
30.0.0.0/24 is subnetted, 1 subnets
C 30.1.1.0 is directly connected, Vlan33
Now, were in good shape! Guests need to have their default gateway IP address appropriate SVI here Host_1 should have its gateway set to 20.1.1.11 and 30.1.1.11 to Host_3. After that, the inter-VLAN communication is now in place, as evidenced by the output table below.
# Ping 30.1.1.1 HOST_1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 30.1.1.1, timeout is 2 seconds: !!!!!
The success rate is 100 percent (5 / 5), round-trip min / avg / max = 1/1/4 ms
# Ping 20.1.1.1 HOST_3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 20.1.1.1, timeout is 2 seconds: !!!!!
The success rate is 100 percent (5 / 5), round-trip min / avg / max = 1/2/4 ms