Lab Objective
Configure static routes on two routers using next-hop IP addresses rather than outgoing interfaces, verify connectivity, and compare the resulting routing table format against the interface-based method from the previous lab.
Lab Purpose
Next-hop-based static routes are the generally preferred syntax for most scenarios, since they avoid the excessive ARP overhead that interface-based routes can cause on multi-access networks, discussed in the previous lab. Understanding exactly how this method appears in the routing table is essential for correctly reading real-world configurations.
Lab Topology
R1 ---- Serial0/0/0 ------ Serial0/0/0 ---- R2
R1: 10.21.21.1/30, LAN 192.168.11.0/24 (Loopback1)
R2: 10.21.21.2/30, LAN 192.168.21.0/24 (Loopback1)Task 1: Configure Basic Addressing
Configure the serial interfaces and a loopback on each router representing its local LAN.
Task 2: Configure a Static Route Using a Next-Hop Address on R1
On R1, configure a static route to R2's LAN using R2's serial interface IP address as the next hop.
Task 3: Configure the Equivalent Route on R2
On R2, configure a static route to R1's LAN using R1's serial interface IP address as the next hop.
Task 4: Verify Connectivity
Confirm R1 can reach R2's LAN and vice versa.
Task 5: Compare the Routing Table Entry Format
Examine how this route appears in the routing table, contrasting it with the "directly connected" format seen in the previous lab's interface-based route.
Solution and Verification
R1(config)# interface serial0/0/0
R1(config-if)# ip address 10.21.21.1 255.255.255.252
R1(config-if)# no shutdown
R1(config-if)# exit
R1(config)# interface loopback1
R1(config-if)# ip address 192.168.11.1 255.255.255.0R2(config)# interface serial0/0/0
R2(config-if)# ip address 10.21.21.2 255.255.255.252
R2(config-if)# clock rate 64000
R2(config-if)# no shutdown
R2(config-if)# exit
R2(config)# interface loopback1
R2(config-if)# ip address 192.168.21.1 255.255.255.0R1(config)# ip route 192.168.21.0 255.255.255.0 10.21.21.2
-- The next-hop IP address (10.21.21.2, R2's
-- serial interface) is specified instead of
-- R1's own outgoing interface nameR2(config)# ip route 192.168.11.0 255.255.255.0 10.21.21.1R1# ping 192.168.21.1
!!!!!
Success rate is 100 percent (5/5)R1# show ip route static
S 192.168.21.0/24 [1/0] via 10.21.21.2
-- Notice the route now explicitly shows
-- "via 10.21.21.2" along with the administrative
-- distance/metric pair [1/0] -- a clear contrast
-- with the "directly connected" phrasing the
-- interface-based route showed in the previous labKey Takeaway
A next-hop-based static route requires the router to perform a recursive lookup: it must first determine which local interface can actually reach that next-hop address before it can forward traffic, whereas an interface-based route skips this step entirely. This recursive lookup is a small amount of extra processing, but it is exactly what avoids the excessive per-destination ARP behavior that makes interface-based routes problematic on multi-access networks.