Load-Sharing over Synchronous Links

Figure 5-2 shows two serial connections used to implement a single synchronous PPP link between two local area networks (LANs). Two hosts (epic and odyssey) running Solstice PPP act as routing gateways between the two networks. Neither host requests peer authentication.

Figure 5-2 Load-sharing over Synchronous Links

This example is similar to the basic synchronous link described on "Synchronous LAN to LAN Configuration"; however, both on-board serial ports are used in a load-sharing configuration to double the available bandwidth.

Load-sharing is a Sun-specific enhancement to the standard Point-to-Point Protocol (PPP). Both hosts must be running Solstice PPP, and, for optimum performance, both serial devices must be operating with the same line speed.

The two hosts act as IP routers in this configuration; therefore, the file /etc/gateways must exist on each host so that IP datagrams are routed correctly.

PPP Configuration File (ppp.conf) for epic:

ifconfig ipdptp0 plumb
ifconfig ipdptp0 epic odyssey netmask 255.255.255.0 mtu 1500 up

sync_path
		ip_interface      ipdptp0
		unix_device       zsh0

sync_path
		ip_interface      ipdptp0
		unix_device       zsh1

PPP Configuration File (ppp.conf) for odyssey:

ifconfig ipdptp0 plumb
ifconfig ipdptp0 odyssey epic netmask 255.255.255.0 mtu 1500 up

sync_path
		ip_interface     ipdptp0
		unix_device      zsh0

sync_path
		ip_interface     ipdptp0
		unix_device      zsh1

Link Configuration Files (link.conf) for epic and odyssey:

sync_device          syncdev0
    unix_device      zsh0
    line_speed       19200
    tx_clock         baud
    rx_clock         rxc

sync_device          syncdev1
    unix_device      zsh1
    line_speed       19200
    tx_clock         baud
    rx_clock         rxc