Protocols And Standards - 3Com 4210G Series Configuration Manual

Sub-option 1: IP address of the primary network calling processor, which is a server serving as the
network calling control source and providing program downloads.
Sub-option 2: IP address of the backup network calling processor that DHCP clients will contact
when the primary one is unreachable.
Sub-option 3: Voice VLAN ID and the result whether DHCP clients take this ID as the voice VLAN
or not.
Sub-option 4: Failover route that specifies the destination IP address and the called number (SIP
users use such IP addresses and numbers to communicate with each other) that a SIP user uses
to reach another SIP user when both the primary and backup calling processors are unreachable.
You must define the sub-option 1 to make other sub-options effective.

Protocols and Standards

RFC 2131: Dynamic Host Configuration Protocol
RFC 2132: DHCP Options and BOOTP Vendor Extensions
RFC 1542: Clarifications and Extensions for the Bootstrap Protocol
RFC 3046: DHCP Relay Agent Information Option
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