User's Manual

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ASSA ABLOY Hospitality
66 3081 004-23
Appendix F: Gateway boot-up
1. When a ZigBee gateway comes out of reset, it reads its IP configuration
from a non-volatile memory.
2. If 'Dynamic IP Address' is set to Disable (see Appendix D): the gateway
sets its IP address to the address stored in the config memory. Continue at
step 13 below.
3. If 'Dynamic IP Address' is set to Enable (see Appendix D): the gateway
sends a DHCP Request packet with IP destination address 255.255.255.255,
i.e. IP broadcast, requesting its most recently used IP address.
4. If the network/subnet configuration has not changed, the DHCP server will
most likely send a DHCP ACK packet, allowing the gateway to continue to
use the same IP. The DHCP server may use either IP broadcast or unicast for
this packet; broadcast is however most commonly used. Continue at step 10
below.
5. If the DHCP server is unwilling to let the gateway use the same address as
before, or if the requested IP is out of scope, it sends a DHCP NAK.
6. Then the gateway resets its IP address to 0.0.0.0 and sends a DHCP Discover
packet with IP destination address 255.255.255.255; IP broadcast.
7. If a DHCP server is available, it sends a DHCP Offer packet. Since the gateway
has no valid IP address, the DHCP server must send to IP destination
255.255.255.255; IP broadcast.
8. The gateway receives the offer and sends a DHCP Request packet, as in step 3
above, but this time requests the IP address offered by the DHCP server.
9. The DHCP server sends a DHCP ACK packet, confirming that the gateway may
start using the new IP address. Unlike the ACK in step 4 above, this ACK
packet must be sent to IP destination address 255.255.255.255 (IP broadcast),
since the gateway has not got any confirmed IP address yet.
10.The gateway performs gratuitous ARP (Address Resolution Protocol) to ensure
that no other host has got the same IP.
11.If IP collision is detected, the gateway sends a DHCP Decline packet which
refuses the assigned IP address and restarts the gateway’s IP acquirement
procedure.
12. New functionality, Zigbee gateway version 2.3.0 and later: If there is no DHCP
server available on the subnet, the gateway self-assigns an IP address from the
IPv4 Local Link address space (169.254.0.0/16), and sends gratuitous ARP to
ensure that no other host has got the same IP.
13. The gateway reads the most recently used Visionline server IP address and
tries to open a TCP connection to the server.
14. If the TCP connection attempt fails, the gateway will continue to try
connections to the same IP over and over again – unless it detects that the
network/subnet setup has changed, e.g. the gateway may have been moved to
a new location. Then it will send an application specific service discovery
request (announcement broadcast) with IP destination address
255.255.255.255; IP broadcast.
14 b. New functionality, Zigbee gateway version 2.3.0 and later: Even if the
network/subnet setup is unchanged, but long time (one hour) has elapsed
without any successful TCP connection with the Visionline server, the gateway
will start sending service discovery requests.