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LIN6-11292 : IPv4: Router TTL value is applied globally in resource layer (Linux)

Created: May 25, 2016    Updated: Dec 3, 2018
Resolved Date: Jul 25, 2016
Found In Version:
Fix Version:
Severity: Standard
Applicable for: Wind River Linux 6
Component/s: Kernel


Per namespace is what we want to be able to configure, it’s modelled that way in our product. 
The ttl attribute is located under the Router MO (ManagedElement=1,Transport=X,Router=X). 
When we create a new Router MO it will trigger creation of a new namespace in Linux and 
in the new namespace we want to somehow be able to set ttl, for instance /proc/sys/net/ipv4/ip_default_ttl. 

1.	root@du1:~# ip netns add x 
2.	root@du1:~# ip netns exec x bash 
3.	root@du1:~# cat /proc/sys/net/ipv4/ip_default_ttl 
cat: /proc/sys/net/ipv4/ip_default_ttl: No such file or directory 

BR Fredric 

1.1	Trouble summary and/or commercial effect 
Router TTL value is applied globally in resource layer (Linux). This has the effect that it will not be possible to have different TTL values on different virtual routers. 

The setting for TTL is done by writing to file #define SYSCTL_IPV4_TTL_KEY "/proc/sys/net/ipv4/ip_default_ttl" without changing namespace. This will apply for all routers created because this settings file is globally for all new namespaces created. 
This settings file can't be located after creating namespace so RCS or Windriver maybe have to patch Kernel. 

See function handle_set_ttl(...) in dpm_ifm.c 

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