Contents

• Inter Sub Domain Mobility
• Introduction
• Point of Presence at Anchor Switch

Inter Sub Domain Mobility

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• Introduction
• Point of Presence at Anchor Switch

Introduction

This section focuses specifically on mobility events that occur across mobility sub-domains. An inter sub-domain mobility event occurs when a user moves from his home sub-domain to a foreign sub-domain. When the station initially roams to the foreign sub-domain, the foreign Mobility Controller signals the mobility event through the Mobility Oracle. This causes the station's traffic to be tunneled between the MCs in both sub-domains.

Point of Presence at Anchor Switch

When a station moves across sub-domains, the home and foreign MCs ensure that all of the station's traffic is tunneled.

Figure 1.

Tunneling across sub-domains when the client roams from Anchor Switch to Foreign Switch

The following events happen when a station roams across sub-domains with the anchor switch in the home sub-domain as its point of presence:

• A station joins the network by associating to the AP on switch A and is provided with an IP address from a subnet available on it.Its traffic is natively bridged at the switch and no tunneling is required. switch A is both the point of presence and point of attachment for the station.
• When the station roams to switch B where the same subnet is not available, the information is provided in the handoff process.
• When the handoff is complete, the mobile announce message is sent from switch B to the MC in foreign sub-domain.
• The MC belonging to the foreign sub-domain will then tunnel the mobile announce message to the MO. This cause the stations traffic to be tunneled between the MCs in both the sub-domains.
• The MO will tunnel the mobile announce message to the MC in the home sub-domain.
• The MC in the home sub-domain will then tunnel the traffic to the anchor switch.

Tunneling across sub-domains with the Anchor Switch in the home sub-domain is the point of presence

The following events happen when a station roams across sub-domains with the anchor switch in the home sub-domain as its point of presence:

• A station joins the network by associating to the AP on switch A and is provided with an IP address from a subnet available on it.Its traffic is natively bridged at the switch and no tunneling is required. switch A is both the point of presence and point of attachment for the station.
• When the station roams to switch B where the same subnet is not available, the information is provided in the handoff process.
• When the handoff is complete, the anchor switch (Switch A) sends the handoff complete message to Switch B.
• The MC in the foreign sub-domain then forwards the handoff complete message to the MC in the home sub-domain.
• The MC belonging to the foreign sub-domain will then tunnel the traffic to the MO and finally reached the MC in the home sub-domain.
• The MC in the home sub-domain will then tunnel the traffic to the anchor switch.
• The anchor switch continues to be the point of presence for the station.
• The Switch B will contain the point of attachment.