H3C Technologies H3C WX6000 Series Access Controllers - Manual (Page 380)

35-7
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Sub-option 2: IP address of the backup network calling processor that DHCP clients will contact
when the primary one is unreachable.
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Sub-option 3: Voice VLAN ID and the result whether DHCP clients take this ID as the voice VLAN
or not.
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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 take effect.
Protocols and Standards
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RFC2131: Dynamic Host Configuration Protocol
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RFC2132: DHCP Options and BOOTP Vendor Extensions
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RFC1542: Clarifications and Extensions for the Bootstrap Protocol
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RFC 3046: DHCP Relay Agent Information Option