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Configuring the Point-to-Point Protocol (PPP)

IP options

The following options define how a bundle handles the IP network protocol:


Local address assignment
How the IP address of the local end of a PPP link is to be negotiated:

by local and remote can override
The IP address specified locally is preferred but the remote end of the PPP link may override it.

by local and remote cannot override
Only the IP address specified locally may be used.

by remote
The remote end of the PPP link must specify the local IP address.

use address allocation server
Use any IP address from the specified Address Allocation Server pool.

Local address
An IP address, a resolvable name, or an Address Allocation Server pool tag that will be used to assign an IP address for the local end of a PPP link. If you need to define a pool tag, click on Edit to invoke the Address Allocation Manager.

Remote address assignment
How the IP address of the remote end of a PPP link is to be negotiated:

by local and remote can override
The IP address specified locally is preferred but the remote end of the PPP link may override it.

by local and remote cannot override
Only the IP address specified locally may be used.

by remote
The remote end of the PPP link must specify the remote IP address.

use address allocation server
Use any IP address from the specified Address Allocation Server pool.

Remote address
An IP address, a resolvable name, or an Address Allocation Server pool tag that will be used to assign an IP address for the remote end of a PPP link. If you need to define a pool tag, click on Edit to invoke the Address Allocation Manager.


NOTE: If you require an outgoing PPP link to be brought up on demand, you must enter local and remote IP addresses even if the service provider will override them during negotiation. A service provider may assign you typical IP addresses and a network mask that you can use to configure each end of the link.

If in doubt, leave the entries blank, configure the link to be brought up manually using pppattach, and use the command ppptalk status bundle tag to examine the IP addresses that are actually negotiated for the link. Then change the link to be brought up on demand, select remote address assignment, and enter the discovered addresses as the local and remote address. Although the service provider will probably override these addresses, they will provide enough information to allow the link to be brought up.



Use as default route
Select Yes if the default route for IP datagrams to outside networks should be established via the new PPP interface when the link is brought up. The route will also be deleted when the link is taken down again. Select No if the local host already has a network interface and you do not want this to stop being the default route.

Act as a gateway
Select Yes if the host at your end of the PPP link will act as a router for packets between the local network and the remote end of the link. Select No if you do not want the local machine to act as a router or it is not connected to a local network.

Act as proxy for ARP
If your host is configured to act as a gateway, select Yes if it will also act as a proxy on the local network on behalf of the host at the remote end of the PPP link. This is necessary if the IP address of the remote end of the link defines it to be on the local network. Because the PPP interface of the machine at the remote end of the link does not have a hardware (MAC) address, it cannot answer Address Resolution Protocol (ARP) requests for this address from machines on the local network. The proxy machine must instead answer all ARP requests on behalf of the remote machine with its own MAC address. It examines the destination IP address of all network packets that are sent to its MAC address. If a packet's destination IP address is that of the machine at the remote end of a PPP link, it forwards the packet on the appropriate PPP interface.

Network mask
The network mask (``netmask'') expressed in dotted-decimal notation (for example, 255.255.255.0). This will be applied to the PPP interface at the local end of the PPP link. If the local machine is also configured to act as an ARP proxy for the remote side, the netmask configured at both ends of the link should be the same as that in use on the local network.

© 2004 The SCO Group, Inc. All rights reserved.
UnixWare 7 Release 7.1.4 - 22 April 2004