3Com WX4400 3CRWX440095A - Manual (Page 189)

MAP Overview 189
Boot Process for
Distributed MAPs
When a distributed MAP boots on the network, it uses the process
described in this section. Note that this process applies only to distributed
MAPs; it does not apply to a directly connected MAP. The boot process
for a directly connected MAP occurs strictly between the MAP and WX
switch and makes no use of the network’s DHCP or DNS services.
The boot process for a distributed MAP consists of the following steps:
1 Establishing connectivity on the network
2 Contacting a WX switch
3 Loading and activating an operational image
4 Obtaining configuration information from the WX switch
These steps are described in more detail in the following sections.
Establishing Connectivity on the Network
When a MAP is first powered on, its bootloader obtains an IP address for
the MAP. The IP address is either obtained through DHCP (the default) or
can be statically configured on the MAP.
How a Distributed MAP Obtains an IP Address through DHCP
By default, a distributed MAP obtains its IP address through DHCP. The
MAP brings up the link on the MAP’s port 1 and attempts the boot
process outlined below.
1 The MAP sends a DHCP Discover message from the MAP’s port 1 to the
broadcast address.
2 If a DHCP server is present on the subnet or through a router configured
to relay DHCP, the server replies with a unicast DHCP Offer message. The
Offer message must contain the following parameters:
„
IP address for the MAP
„
Domain name of the network
„
IP address of the network’s DNS server
„
IP address of the subnet’s default gateway router (gateway)
Optionally, the DHCP Offer message can also contain a list of WX IP
addresses or fully qualified hostnames, in the Option 43 field.
3 The MAP broadcasts a DHCP Request to the DHCP servers, and receives an
Ack from a DHCP server. The MAP then configures its network connection
with the information contained in the Ack message from that server.