User's Guide

Table Of Contents
hwc_intro.fm
Overview of the HiPath Wireless Controller, Access Points and Convergence Software solution
HiPath Wireless Controller, Access Points and Convergence Software and your network
9034530-02,
March 2010
HiPath Wireless Controller, Access Points and Convergence Software V7.11, User Guide 35
Open Shortest Path First (OSPF, version 2) (RFC2328) – Use OSPF to
allow the HiPath Wireless Controller to participate in dynamic route selection.
OSPF is a protocol designed for medium and large IP networks with the ability
to segment routes into different areas by routing information summarization
and propagation. Static Route definition and OSPF dynamic learning can be
combined, and the precedence of a static route definition over dynamic rules
can be configured by selecting or clearing the Override dynamic routes
option checkbox.
Next-hop routing – Use next-hop routing to specify a unique gateway to
which traffic on a VNS is forwarded. Defining a next-hop for a VNS forces all
the traffic in the VNS to be forwarded to the indicated network device,
bypassing any routing definitions of the controller's route table.
2.3.6 Mobility and roaming
In typical simple configurations, APs are setup as bridges that bridge wireless
traffic to the local subnet. In bridging configurations, the user obtains an IP
address from the same subnet as the AP, assuming no VLAN trunking functinality.
If the user roams between APs on the same subnet, it is able to keep using the
same IP address. However, if the user roams to another AP outside of that
subnet, its IP address is no longer valid. The user's client device must recognize
that the IP address it has is no longer valid and re-negotiate a new one on the
new subnet. This mechanism does not mandate any action on the user. The
recovery procedure is entirely client device dependent. Some clients
automatically attempt to obtain a new address on roam (which affects roaming
latency), while others will hold on to their IP address. This loss of IP address
continuity seriously affects the client's experience in the network, because in
some cases it can take minutes for a new address to be negotiated.
The HiPath Wireless Controller, Access Points and Convergence Software
solution centralizes the user's network point of presence, therefore abstracting
and decoupling the user's IP address assignment from that of the APs location
subnet. That means that the user is able to roam across any AP without loosing
its own IP address, regardless of the subnet on which the serving APs are
deployed.
In addition, a HiPath Wireless Controller can learn about other HiPath Wireless
Controllers on the network and then exchange client session information. This
enables a wireless device user to roam seamlessly between different Wireless
APs on different HiPath Wireless Controllers.