Avaya Troubleshooting Routers Instrukcja Naprawy Pobierz pdf (Strona 119)

Troubleshooting a Network Connection Problem

6-13

1. Compare the endstation’s interface number, network number, and

subnet mask to those of the router’s interface. The network and subnet

numbers must be the same, except that the endstation’s subnet mask does

not have to include as many octets as the router’s (Figure 6-

1).

Figure 6-1. Comparing the Endstation and Router Conﬁgurations

The subnet mask allows the router to determine which trafﬁc to route to each

segment. In Figure 6-

1, the router’s subnet mask must include the third octet if

other subnets in the 129.122 network connect to the router. Usually in such

conﬁgurations, you conﬁgure Proxy ARP (Address Resolution Protocol) to

run on the router’s interface because the endstation does not know that it has

to go through the router to get to other subnets of the 129.122.0.0 network.

2. Disable IP on the router’s interface, and try to ping the IP address of the

router again.

If the ping succeeds, a device with a duplicate IP address is on the segment.

3. Enable IP on the router’s interface and try to ping other stations on the

segment that is reporting problems.

Host

Router

Network 129.122.32.0

Interface 129.122.32.1

Subnet mask 255.255.255.0

Network 129.122.0.0

Interface 129.122.32.66

Subnet mask 255.255.0.0

1 2 ... 114 115 116 117 118 119 120 121 122 123 124 ... 253 254

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Avaya Troubleshooting Routers Instrukcja Naprawy Strona 119