Renew dhcp on sip request timeout – Cisco Linksys SPA9000 User Manual
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Linksys SPA9000 Administrator Guide
Document Version 3.01
Chapter 4 Configuring SPA9000 Features
Enhancements in Release 5.1
The first part of the REGISTER enhancement adds a randomized delay on top of the corresponding
nominal retry interval:
•
<Reg Retry Random Delay> = range of randomized delay to add to <Reg Retry Intvl> before
retrying REGISTER (when <Reg Retry Intvl> is applied)
•
<Reg Retry Long Random Delay> = range of randomized delay to add to <Reg Retry Long Intvl)
before retrying REGISTER (when <Reg Retry Long Intvl> is applied)
The second enhancement is to allow exponential back off of the <Reg Retry Intvl> for each retry until
it reaches the maximum value defined in the <Reg Retry Intvl Cap> parameter. If the value of the
<Reg Retry Intvl Cap> parameter is less than the <Reg Retry Intvl), the exponential back off feature is
disabled.
Renew DHCP On SIP Request Timeout
The SPA9000 may sometimes have an invalid IP address even though the DHCP lease has not expired.
In these cases, the SPA9000 may not receive any packets until it renews the IP address lease with the
DHCP server. The Renew DHCP On SIP Request Timeout feature, introduced in Release 5.1, allows the
SPA9000 to discover that the currently assigned IP address is no longer valid. This feature triggers a
DHCP lease renewal whenever indicators suggest that the SPA9000 is not receiving packets.
The SPA9000 periodically sends SIP requests to register, make calls, and so forth. Each SIP request
normally receives a corresponding reply. If the SPA9000 fails to receive a reply to a SIP request this may
indicate an invalid local IP address.
With this enhancement, when the SPA9000 fails to receive a reply to a SIP request, a timer is started. If
no reply to any SIP request is received before the timer expires, the SPA9000 automatically performs a
DHCP lease renewal. If the renewal results in the same IP address, no further action is taken. If the
renewal results in a new IP address assignment, the SPA9000 reboots.