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System Administration Guide: IP Services     Oracle Solaris 10 8/11 Information Library
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Part I Introducing System Administration: IP Services

1.  Oracle Solaris TCP/IP Protocol Suite (Overview)

Part II TCP/IP Administration

2.  Planning Your TCP/IP Network (Tasks)

3.  Introducing IPv6 (Overview)

4.  Planning an IPv6 Network (Tasks)

5.  Configuring TCP/IP Network Services and IPv4 Addressing (Tasks)

6.  Administering Network Interfaces (Tasks)

7.  Configuring an IPv6 Network (Tasks)

8.  Administering a TCP/IP Network (Tasks)

9.  Troubleshooting Network Problems (Tasks)

10.  TCP/IP and IPv4 in Depth (Reference)

11.  IPv6 in Depth (Reference)


12.  About DHCP (Overview)

13.  Planning for DHCP Service (Tasks)

14.  Configuring the DHCP Service (Tasks)

15.  Administering DHCP (Tasks)

16.  Configuring and Administering the DHCP Client

17.  Troubleshooting DHCP (Reference)

18.  DHCP Commands and Files (Reference)

Part IV IP Security

19.  IP Security Architecture (Overview)

20.  Configuring IPsec (Tasks)

21.  IP Security Architecture (Reference)

22.  Internet Key Exchange (Overview)

23.  Configuring IKE (Tasks)

24.  Internet Key Exchange (Reference)

25.  IP Filter in Oracle Solaris (Overview)

26.  IP Filter (Tasks)

Part V Mobile IP

27.  Mobile IP (Overview)

What's New in Mobile IP

Introduction to Mobile IP

Mobile IP Functional Entities

How Mobile IP Works

Agent Discovery

Agent Advertisement

Agent Advertisement Over Dynamic Interfaces

Agent Solicitation

Care-of Addresses

Mobile IP With Reverse Tunneling

Limited Private Addresses Support

Mobile IP Registration

Network Access Identifier (NAI)

Mobile IP Message Authentication

Mobile Node Registration Request

Registration Reply Message

Foreign Agent Considerations

Home Agent Considerations

Dynamic Home Agent Discovery

Routing Datagrams to and From Mobile Nodes

Encapsulation Methods

Unicast Datagram Routing

Broadcast Datagrams

Multicast Datagram Routing

Security Considerations for Mobile IP

28.  Administering Mobile IP (Tasks)

29.  Mobile IP Files and Commands (Reference)


30.  Introducing IPMP (Overview)

31.  Administering IPMP (Tasks)

Part VII IP Quality of Service (IPQoS)

32.  Introducing IPQoS (Overview)

33.  Planning for an IPQoS-Enabled Network (Tasks)

34.  Creating the IPQoS Configuration File (Tasks)

35.  Starting and Maintaining IPQoS (Tasks)

36.  Using Flow Accounting and Statistics Gathering (Tasks)

37.  IPQoS in Detail (Reference)



Routing Datagrams to and From Mobile Nodes

This section describes how mobile nodes, home agents, and foreign agents cooperate to route datagrams for mobile nodes that are connected to a foreign network. See Overview of the Solaris Mobile IP Implementation for Mobile IP functions that are supported in the Solaris OS.

Encapsulation Methods

Home agents and foreign agents use one of the available encapsulation methods to support datagrams that use a tunnel. Defined encapsulation methods are IP-in-IP Encapsulation, Minimal Encapsulation, and Generic Routing Encapsulation. Foreign agent and home agent cases, or indirect colocated mobile node and home agent cases, must support the same encapsulation method. All Mobile IP entities are required to support IP-in-IP Encapsulation.

Unicast Datagram Routing

When registered on a foreign network, the mobile node uses the following rules to choose a default router:

Broadcast Datagrams

When a home agent receives a broadcast datagram or multicast datagram, the home agent only forwards the datagram to mobile nodes that have specifically requested that they receive them. How the home agent forwards broadcast and multicast datagrams to mobile nodes depends primarily on two factors. Either that mobile node is using a foreign-agent provided care-of address, or the mobile node is using its own colocated care-of address. The former means that the datagram must be double encapsulated. The first IP header identifies the mobile node for which the datagram is to be delivered. This first IP header is not present in the broadcast or multicast datagram. The second IP header identifies the care-of address, and is the usual tunnel header. In the latter instance, the mobile node is decapsulating its own datagrams, and the datagram needs only to be sent through the regular tunnel.

Multicast Datagram Routing

To begin receiving multicast traffic when a mobile node is visiting a foreign subnet, a mobile node can join a multicast group in any of the following ways:

Multicast routing depends on the IP source address. A mobile node that is sending a multicast datagram must send the datagram from a valid source address on that link. So a mobile node that is sending multicast datagrams directly on the visited network must use a colocated care-of address as the IP source address. Also, the mobile node must have joined the multicast group that is associated with the address. Similarly, a mobile node that joined a multicast group while on its home subnet before roaming, or joined the multicast group while roaming through a reverse tunnel to its home agent, must use its home address as the IP source address of the multicast datagram. Thus, the mobile node must have these datagrams reverse-tunneled to its home subnet as well, either through itself by using its colocated care-of address, or through a foreign agent reverse tunnel.

While it seems more efficient for a mobile node to always join from the subnet that the mobile node is visiting, it is still a mobile node. Consequently, the mobile node would have to repeat the join every time the mobile node switches subnets. The more efficient way is for the mobile node to join through its home agent, and not have to carry this overhead. Also, multicast sessions might be present that are only available from the home subnet. Other considerations might also force the mobile node to participate in a specific way.