Figure A12-9; Cli Commands Providing Routing Information; Depending On Proxy Arp When Routing Is More Reliable - Bay Networks 5390 Administering

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Use the following commands to obtain information about IP routing on your network.

To display the contents of the Model 5390 routing table, use the CLI netstat –r command

(see Displaying the Model 5390 Routing Table on page A12-64).

To display the contents of the routing cache (which contains user-conﬁgured routes), use the

CLI netstat –C command (see Displaying the route cache on page A12-67).

Common Conﬁguration Errors

In conﬁguring routing, users make four common mistakes:

Attempting to route through Proxy ARP interfaces. As stated several times in this chapter, do

not attempt to conﬁgure a static route whose next-hop address is a Proxy ARP interface.

Doing so causes packets to be routed improperly or not routed at all.

Conﬁguring network/subnet addresses that overlap.

Conﬁguring non-contiguous subnets.

The following sections describe in detail the ﬁnal three of these four mistakes.

Depending on Proxy ARP When Routing is More Reliable

Figure A12-9 shows a subnet conﬁguration in which a PC can dial into one of two Model 5390

servers. Because all nodes are on the same subnet, it is tempting to assume that host01could reach

the PC via Proxy ARP. However, hosts and Model 5390 servers retain Proxy ARP information long

enough so that it is possible for the PC to have dialed into one Model 5390 server, disconnected,

and then dialed into the other Model 5390 server before host01 updated its ARP table. Therefore,

the host may not have the up-to-date Proxy ARP information.

To avoid this kind of confusion, assign the PC a different subnet address—for example, 132.254.6.x.

This forces host01 and the Model 5390 servers to use routing updates (which are more frequent

than ARP requests) to determine the Model 5390 server to which the PC is attached. (Make sure

that active routing is enabled; see Enabling and Disabling Active RIP on page A12-47. Also, make

sure that host01 supports either subnet or host routes.)

Internet Protocol (IP) Routing