Monitoring Routes; Clearing Routes - HP 7102dl - ProCurve Secure Router Configuration Manual

Monitoring Routes

You can monitor the route that packets actually take through the network by
using the traceroute command. Enter the command follow by the destination
address for the route you want to trace:
Syntax: traceroute <A.B.C.D>
The router sends out a series of pings with steadily incrementing TTLs, so that
each successive ping reaches one hop closer to the destination. The router
records the addresses of the routers that return the pings, thus building up a
list of every hop between itself and the destination. (See Figure 15-34.)
ProCurveSR7102dl#traceroute 192.168.100.2
Type CTRL+C to abort.
Tracing route to 192.168.100.2 over a maximum of 30 hops
1 2ms 2ms
2 4ms 4ms
3 4ms 5ms
Figure 15-34. traceroute Command
Tracing routes allows you to monitor actual traffic flow (although in a neces-
sarily limited fashion). When traffic does not reach its destination, you can
determine which network node cannot forward it. You can then troubleshoot
the device with the problem.
When traffic can take more than one route through a network, you can use
the traceroute command to discover which path routers have selected. If you
determine that routers are using high-cost paths unnecessarily, you can make
adjustments accordingly. For example, you can assign a higher cost to an
OSPF interface.

Clearing Routes

You can clear all routes that the router has discovered using a routing protocol.
This can be useful when the network is having trouble converging, or if the
router has learned unreliable routes. Enter:
Syntax: clear ip route [** | <A.B.C.D> <subnet mask | /prefix length>
IP Routing—Configuring RIP, OSPF, BGP, and PBR
2ms 10.1.1.2
4ms 10.2.2.1
4ms 192.168.100.2
Destination
Troubleshooting Routing
Next hop—
directly
connected
neighbor
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