Configuring a Relay Agent

It is likely that most or all of your NFS cluster’s clients are attached to the same subnetwork as your cluster server. If not, a gateway (a device such as a router, or a computer) can be used to connect two or more networks.

Once a gateway is attached, the server can boot clients that are on subnetworks that the server is not directly attached to. There can only be one gateway that separates the server from the remote client.

A relay system is a computer that is on the same subnetwork as the clients to be booted. A relay agent is software on the relay system and server that is configured to pass client and server messages between the two subnetworks.

There are some restrictions in setting up a relay system:

The relay system must be a Series 700 or Series 800 computer in the same subnet as the client. This machine must be running HP-UX 10.01 (or later) from a local file system; that is, it cannot itself be a client of another NFS cluster.

The client must be only one hop from the server; that is, the client and server subnetworks must be connected through a single router or gateway. You can verify this by running /usr/sbin/ping with the -o option from the relay system to the server. For example, to check the hops from tinkrbel to peter:

tinkrbel: /usr/sbin/ping -o peter -n 1
PING peter.neverlnd.com: 64 byte packets
64 bytes from 153.13.115.149: icmp_seq=0. time=18. ms
peter.neverlnd.com PING Statistics
1 packets transmitted, 1 packets received, 0% packet loss
round-trip (ms)  min/avg/max = 18/18/18
1 packets sent via:
      153.13.112.1     - croc-gw.neverlnd.com
      153.13.115.149   - peter.neverlnd.com
      153.13.104.1     - croc-gw.neverlnd.com
      153.13.105.109   - tinkrbel.neverlnd.com

Note that the packet went from the relay system tinkrbel via the gateway croc-gw to the server peter and returned back to tinkrbel via croc-gw. This shows that tinkrbel is only one gateway (croc-gw) away from peter.

To configure the relay agent, follow these steps:




	NOTE: You must make the changes on the relay system manually (that is, without using SAM). Later, when you use SAM to configure a gateway client, use the IP address of the relay system in the “`Default Route`” field of the “`Define Clients`” screen.

In the file /etc/inetd.conf, add the following line if it does not already exist:
```
bootps       dgram  udp wait   root /usr/lbin/bootpd   bootpd
```
In the file /etc/bootptab, add the following information for each client that may be booted across the gateway served by this relay system. (See bootpd(1M) and comments in the file /etc/bootptab for further information.)
# The following is a client that boots from server: client's_host_name:\ ht=ethernet:\ ha=client's_hardware_address:\ bp=server's_IP_address:\ hp=1
The hop count, hp, must be 1.
For example, using the information displayed by the ping command above to configure client wendy to boot from server peter across a gateway using relay system tinkrbel, install the following entry on tinkrbel:
# client 'wendy' (ha) boots from server 'peter' (bp) wendy:\ ht=ethernet:\ bp=153.13.115.149:\ ha=08009935c990:\ bp=153.13.115.149:\ hp=1
In the /etc/rc.config.d/netdaemons file, set the value of START_RBOOTD to 1 to ensure that the rbootd daemon starts at boot time:
START_RBOOTD=1
If it is not running already, start the rbootd daemon (see rbootd(1M)).
The rbootd daemon provides NFS diskless cluster support for Series 700 clients with older boot ROMs designed for the “DUX” clustered environment without requiring boot ROM modifications (SAM automatically configures rbootd on the cluster server).

Naming services used by the server are not transferred to diskless clients that boot over a gateway. If the server uses DNS or NIS services, these services will have to be manually configured on the gateway client. Gateway clients are only provided with a copy of the server /etc/hosts file.

Configuring a Relay Agent

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