BLADE OS™ Application Guide HP GbE2c Ethernet Blade Switch for c-Class BladeSystem Version 5.1 Advanced Functionality Software

Table Of Contents
BLADE OS 5.1 Application Guide
170 Chapter 9: Basic IP Routing BMD00113, September 2009
Chassis-Based Scheme
Using the chassis option, the chassis ID, slot number, and port information are inserted into the
DHCP request. The format of the information varies depending on the encoding method used by the
DHCP server (option 61 or 82).
Using the DHCP Option 61 Client Identifier
For any non-trunked port: <chassis ID>-<switch slot ID>-<port number>
For static trunk port: <chassis ID>-<switch slot ID>-t<trunk ID>
For an LACP trunk port: <chassis ID>-<switch slot ID>-k<Admin key>
Using the DHCP Option 82 Agent Identifiers
The chassis ID string is encoded in the Agent circuit ID sub-option.
The slot number and port number are encoded in the Agent remote ID sub-option, in
hexadecimal format:
<slot ID><port type><switch unit><port number, 2 bytes>
where:
Slot ID, 1 byte, is the switch slot ID.
Port type, 1 byte, is 0 for non-trunked ports, t for static trunk ports, or k for LACP ports.
Switch unit, 1 byte, is 0.
Port number, 2 bytes, is the port number for non-trunked ports, the trunk number for static
trunk ports, or the admin key for LACP trunk ports.
Automatic Recovery
If you configure one server as the backup to another server, you may want the two servers to use the
same IP address, even though they are in different slots. To address this issue, configure a port as
the backup port of another (active) port on the switch and enable automatic recovery on the switch.
When the active server goes down, the agent remote ID sub-option for packets received on the
backup port will use the port number of its active port, and the backup server will automatically
receive the same IP address as the active server.
Both the active port and the backup port must have the ServerMobility feature enabled.
A configurable timer of 1 to 255 seconds controls how long after a server failure the switch will
wait before permitting the backup server to request the IP address from the DHCP server. The
default is 5 seconds.
Automatic recovery configuration is included in the following ServerMobility example.