sonic-buildimage/files/image_config/interfaces/interfaces.j2
Samuel Angebault 9bf4b0a93e
[baseimage]: Change the loopback mask from /8 to /16 (#5353)
As per the VOQ HLDs, internal networking between the linecards and supervisor is required within a chassis.
Allocating 127.X/16 subnets for private communication within a chassis is a good candidate.
It doesn't require any external IP allocation as well as ensure that the traffic will not leave the chassis.

References:
https://github.com/Azure/SONiC/pull/622
https://github.com/Azure/SONiC/pull/639

**- How I did it**

Changed the `interfaces.j2` file to add `127.0.0.1/16` as the `lo` ip address.
Then once the interface is up, the post-up command removes the `127.0.0.1/8` ip address.
The order in which the netmask change is made matters for `127.0.0.1` to be reachable at all times.

**- How to verify it**

```
root@sonic:~# ip address show dev lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/16 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
```

Co-authored-by: Baptiste Covolato <baptiste@arista.com>
2020-09-15 15:29:48 -07:00

109 lines
4.0 KiB
Django/Jinja

#
{% block banner %}
# =============== Managed by SONiC Config Engine DO NOT EDIT! ===============
# generated from /usr/share/sonic/templates/interfaces.j2 using sonic-cfggen
# file: /etc/network/interfaces
#
{% endblock banner %}
{% block mgmt_vrf %}
{% if (MGMT_VRF_CONFIG) and (MGMT_VRF_CONFIG['vrf_global']['mgmtVrfEnabled'] == "true") %}
auto mgmt
iface mgmt
vrf-table 5000
# The loopback network interface for mgmt VRF that is required for applications like NTP
up ip link add lo-m type dummy
up ip link set dev lo-m master mgmt
up ip addr add 127.0.0.1/16 dev lo-m
up ip link set lo-m up
down ip link delete dev lo-m
{% endif %}
{% endblock mgmt_vrf %}
{% block loopback %}
# The loopback network interface
auto lo
iface lo inet loopback
address 127.0.0.1
netmask 255.255.0.0
post-up ip addr del 127.0.0.1/8 dev lo
{% endblock loopback %}
{% block mgmt_interface %}
# The management network interface
auto eth0
{% if (ZTP_DHCP_DISABLED is not defined) and (ZTP is defined) and (ZTP['mode'] is defined and ZTP['mode']['profile'] == 'active') %}
# ZTP out-of-band interface
allow-hotplug eth0
{% if ZTP['mode']['ipv4'] == 'true' %}
iface eth0 inet dhcp
{% endif %}
{% if ZTP['mode']['ipv6'] == 'true' %}
iface eth0 inet6 dhcp
up sysctl net.ipv6.conf.eth0.accept_ra=1
down sysctl net.ipv6.conf.eth0.accept_ra=0
{% endif %}
{% if ZTP['mode']['inband'] == 'true' %}
{% for port in PORT %}
# ZTP in-band interface {{ port }}
auto {{ port }}
allow-hotplug {{ port }}
{% if PORT_DATA['PORT_TABLE:'+port] is defined and PORT_DATA['PORT_TABLE:'+port]['value']['oper_status'] == 'up' %}
{% if ZTP['mode']['ipv4'] == 'true' %}
iface {{ port }} inet dhcp
{% endif %}
{% if ZTP['mode']['ipv6'] == 'true' %}
iface {{ port }} inet6 dhcp
{% endif %}
{% endif %}
{% endfor %}
{% endif %}
{% else %}
{% if MGMT_INTERFACE %}
{% for (name, prefix) in MGMT_INTERFACE|pfx_filter %}
iface eth0 {{ 'inet' if prefix | ipv4 else 'inet6' }} static
address {{ prefix | ip }}
netmask {{ prefix | netmask if prefix | ipv4 else prefix | prefixlen }}
network {{ prefix | network }}
broadcast {{ prefix | broadcast }}
{% set vrf_table = 'default' %}
{% if (MGMT_VRF_CONFIG) and (MGMT_VRF_CONFIG['vrf_global']['mgmtVrfEnabled'] == "true") %}
{% set vrf_table = '5000' %}
vrf mgmt
{% endif %}
########## management network policy routing rules
# management port up rules
up ip {{ '-4' if prefix | ipv4 else '-6' }} route add default via {{ MGMT_INTERFACE[(name, prefix)]['gwaddr'] }} dev eth0 table {{ vrf_table }} metric 201
up ip {{ '-4' if prefix | ipv4 else '-6' }} route add {{ prefix | network }}/{{ prefix | prefixlen }} dev eth0 table {{ vrf_table }}
up ip {{ '-4' if prefix | ipv4 else '-6' }} rule add from {{ prefix | ip }}/{{ '32' if prefix | ipv4 else '128' }} table {{ vrf_table }}
{% for route in MGMT_INTERFACE[(name, prefix)]['forced_mgmt_routes'] %}
up ip rule add to {{ route }} table {{ vrf_table }}
{% endfor %}
# management port down rules
pre-down ip {{ '-4' if prefix | ipv4 else '-6' }} route delete default via {{ MGMT_INTERFACE[(name, prefix)]['gwaddr'] }} dev eth0 table {{ vrf_table }}
pre-down ip {{ '-4' if prefix | ipv4 else '-6' }} route delete {{ prefix | network }}/{{ prefix | prefixlen }} dev eth0 table {{ vrf_table }}
pre-down ip {{ '-4' if prefix | ipv4 else '-6' }} rule delete from {{ prefix | ip }}/{{ '32' if prefix | ipv4 else '128' }} table {{ vrf_table }}
{% for route in MGMT_INTERFACE[(name, prefix)]['forced_mgmt_routes'] %}
pre-down ip rule delete to {{ route }} table {{ vrf_table }}
{% endfor %}
{# TODO: COPP policy type rules #}
{% endfor %}
{% else %}
iface eth0 inet dhcp
metric 202
{% if (MGMT_VRF_CONFIG) and (MGMT_VRF_CONFIG['vrf_global']['mgmtVrfEnabled'] == "true") %}
vrf mgmt
{% endif %}
iface eth0 inet6 dhcp
up sysctl net.ipv6.conf.eth0.accept_ra=1
down sysctl net.ipv6.conf.eth0.accept_ra=0
{% endif %}
{% endif %}
#
source /etc/network/interfaces.d/*
#
{% endblock mgmt_interface %}