Control of Ethernets on Client Systems

Default Control

By default, encp will use the DNS name obtained by the "hostname" command for control messages. Encp uses whatever routing the client system or network administrator sets between the client system and the Enstore system for data transfers.

Typically, the default configuration will suffice for machines with a single network interface, or a machine with a single network interface dedicated for data movement.

Data are moved with the default TCP window size on the machine. There is a potential for an extreme performance degradation if the default window is set too large. A value of about 32K works well at most locations at Fermilab.

enstore.conf -- Detailed Control

Administrators can create an enstore.conf file to allow for multiple network interface cards dedicated to Enstore, and to allow for a different IP address to be used for the encp control socket. The default location for the file is /etc/enstore.conf. The location of the file can be overridden with the environment variable ENSTORE_CONF.

The file format supports comments, a hostname line, and one of more interface lines.

Comment Lines

Comment lines begin with a "pound" sign, "#".
Example:

# this is s comment line

Hostip line

The "hostip" line is used to override the DNS name that encp uses in the bind command when doing a (passive) open on on a socket used to listen for the mover to call it back. There should be 1 hostname lines per enstore.conf file. It must be the IP of one of the IPs listed on an interface entry in this file.
Example:

hostip=131.225.42.42

Interface lines

This feature of enstore.conf is used when data transfers over more than one network interface are necessary. An enstore.conf file would typically contain at least two of these lines, since a single interface can be controlled more conventionally with static routes. Currently the interface lines are only supported and exercised in IRIX machines. The underlying implementation mechanisms for multiple interfaces are portable, and the scheme can be extended on demand. When more than two interfaces are used on IRIX systems, it is necessary to have each interface on its own subnet. The enroute2 executable must be installed and setuid root on the machin for this feature to take effect.

All five keyword must be present on an interface line.

  • The "interface" key word specifies the network device.
  • The "weight" keyword specifies the relative capacity of each interface. For example, if 1 gbps and 100 mbps interfaces are used, they might be assigned weights of 30 and 10, respectively.
  • The "ip" keyword specifies an ip address corresponding to the device on the "interface" keyword.
  • The "gw" keyword specifies an ip address corresponding to the gateway to the Enstore movers for the "interface" keyword.
  • The "cpu" keyword is used on IRIX systems. Network transfers are often CPU limited. The amount of CPU used per transfer can be minimize if the CPU used by encp has hardware affinity with the slot holding the network card, and if the same CPU performs interrupt service on for the network card.
  • Example:
    
    interface=eg2 weight=10 cpu=2 gw=131.225.32.32 ip=131.225.32.31
    interface=eg3 weight=10 cpu=3 gw=131.225.32.36 ip=131.225.32.35
    
    

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    Last modified: Fri Aug 12 16:30:40 CDT 2005