Monitoring Routes - HP ProCurve 7000dl Series Basic Management And Configuration Manual

If a static route will not appear in the routing table, verify that the associated
forwarding interface is up. If necessary, troubleshoot that interface. If you
have configured a next hop address for the static route, you should check the
routing table to ensure that it includes a route to that next hop.
If you want the router to use more than one route to the same destination, you
must enable load sharing with the ip load-sharing command.
If you see a route to the destination that hosts cannot reach, several problems
could be causing traffic to be misrouted:
Another router en route to the destination cannot route the traffic—In this
case, you should use the traceroute command to pinpoint the router that
is not forwarding the traffic. (See "Monitoring Routes" on page 11-27.)
Remember that in order for a ping to be successful, routers must also
know a route back to the source of the ping. You should always make sure
that routes are two-way: the local router knows routes to remote destina-
tions, and remote routers know routes to the local networks.
The route in the local routing table is invalid—Check for miskeyed
information such as the wrong interface number for the forwarding
interface. You must remove the route before re-entering the route with
the correct information. (When you configure more than one static route
to the same destination, the router automatically assigns the second route
a higher administrative distance. Therefore, if you fail to remove the faulty
route, your correction will not take affect.)
Your router's routing table includes the correct route, but it also includes
a more-specific, incorrect route. For example, the router may have dis-
covered a more-specific route using a routing protocol. See "Clearing
Routes" on page 11-28 to learn how to remove dynamic routes from the
table. See Chapter 15: IP Routing—Configuring RIP, OSPF, BGP,
and PBR in the Advanced Management and Configuration Guide to
learn how to troubleshoot routing protocols.

Monitoring Routes

You can monitor the route that packets actually take through the network by
using the traceroute command. Enter the command followed by the destina-
tion 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 11-9.)
IP Routing—Configuring Static Routes
Troubleshooting Static Routing
11-27