[advanced-reboot] Change Dest IP of VM/Server Originated Packets

[tahmed-dev]

Description of PR

Change in PR:1653 changed prefix len and did not change the network
which would result in high chance of collision with DUT vlan IP.
This PR will change the network where VMs' IPs are generated.

signed-off-by: Tamer Ahmed tamer.ahmed@microsoft.com

Summary:
Fixes # (issue)

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Approach

What is the motivation for this PR?

How did you do it?

How did you verify/test it?

pytest platform_tests/test_advanced_reboot.py::test_fast_reboot --testbed=vms12-t0-s6000-1 --inventory=../ansible/str --testbed_file=../ansible/testbed.csv --host-pattern=str-s6000-acs-14 --module-path=../ansible/library --disable_loganalyzer --skip_sanity --reboot_limit=60 --new_sonic_image=http://100.127.20.23/installer/sonic/broadcom/internal-201811/sonic-broadcom.bin 
================================================================================================================================================== test session starts ===================================================================================================================================================
platform linux2 -- Python 2.7.12, pytest-4.6.9, py-1.8.1, pluggy-0.13.1
ansible: 2.8.7
rootdir: /var/host-acs-mgmt-repo/tests, inifile: pytest.ini
plugins: ansible-2.2.2
collected 1 item                                                                                                                                                                                                                                                                                                         

platform_tests/test_advanced_reboot.py .                                                                                                                                                                                                                                                                           [100%]

========================================================================================================================================= 1 passed, 1 warnings in 662.78 seconds =========================================================================================================================================

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation

[lguohan]

is there an example? I probably do not fully understand this.

[tahmed-dev]

those are packets originated from servers. The advanced-reboot.py generate random dest IP in the default_ip_range network. The network is the same as the vlan network and so collision could happen. We are changing the network here to be different from the vlan network in order to prevent collision with dut vlan as reported and fixed here. In the case of default vlan network: 192.168.0.1/21, the default_ip_range will have prefixlen 18 and adds 1 in the 14th position and so network would be: 192.168.64.0/18