- Enterasys Security Router User's Guide

DHCP Client Services
XSR User’s Guide 15-7
Primary and secondary IP addresses on the same interface are not permitted within the same
subnet nor are they allowed within the same subnets already occupied by other interfaces. Also,
the primary IP address must be configured before any secondary address is configured. If the
primary address is DHCP negotiated, its address and mask are unknown until a DHCP server
supplies such addresses.
Interaction with Remote Auto Install (RAI)
When DHCP Client negotiation is conducted during the RAI operations, minor differences occur
in comparison to how the functionality behaves otherwise. The Parameters Request List will contain
the following:
•Subnet Mask
•Routers
• Domain Name Servers
•Host Name
• Bootfile Name
• TFTP Server Address
A timer starts when DHCP Client is created on an interface. Upon the timer’s expiration, DHCP
Client shuts down, informing RAI that address negotiation has failed and, in this case, is never
restarted. RAI then attempts auto install on other interfaces.
In addition to RAI obtaining the address/mask in conventional fashion, the following data is also
obtained when available:
• hostname of the router - (Option 12)
• file name (in order of preference) - file field or Option 67 (Bootfile Name)
• IP address of the TFTP server (in order of preference) - Option 150 (TFTP Server address) or
siaddr field
For more information on RAI, refer to “Managing the XSR” on page 2-1.
DHCP Client Timeouts
The XSR supports the following default FSM (Finite State Machine) timeouts:
Table 15-3 FSM Timeouts
Timeout Default Description
Retry interval 300 seconds Interval to re-enter Initial State if no lease
Select interval 0 seconds (accepts
first valid response)
Interval to accumulate OFFER messages from different servers
Reboot timeout 10 seconds Interval to enter Initial State from Rebooting State if no ACK/NAK
received
Initial interval 3 seconds Exponential backoff period starting with this value
Backoff cutoff 15 seconds Peak backoff period