CCTools Network Options
When working in a cloud or HPC environment, you may find complex
network conditions such as multiple network interfaces, firewalls,
and other conditions. The following environment variables can be
used to shape the network behavior of
Makeflow, Work Queue, Parrot, Chirp, and other tools,
so as to work correctly in these environments.
IPV6 is supported by all of the CCTools components, however it is not turned
on by default because IPV6 is not reliably deployed at all sites. You can
enable IPV6 support with the CCTOOLS_IP_MODE environment variable.
To enable both IPV4 and IPV6 support according to the local system configuration: (recommended use)
To enable only
IPV4 support: (the default)
To enable only
IPV6 support: (not recommended; use only for testing IPV6)
Where it is necessary to combine an address and port together into a single string, an IPV4 combination looks like this:
But an IPV6 combination looks like this:
When creating a listening TCP port, the CCTools will, by default, pick any
port available on the machine. However, some computing sites set up firewall
rules that only permit connections within certain port ranges. To accommodate
this, set the TCP_LOW_PORT
and the CCTools will only use ports within that range.
For example, if your site firewall only allows ports 8000-9000, do this:
The performance of TCP connections over wide area links can be significantly
affected by the "window size" used within the kernel. Ideally, the window size
is set to the product of the network bandwidth and latency, and is managed
automatically by the kernel. In certain cases, you may wish to set it manually
with the TCP_WINDOW_SIZE
environment variable, which gives the window
size in bytes.
For example, to se the window size to 1MB:
if your computing site requires all HTTP requests to be routed through a proxy,
specify that proxy with the HTTP_PROXY
The value should be a semi-colon separated list of proxy URLs, in order
of preference. The final entry may be DIRECT
a direct connection should be attempted if all proxy connections fail.