Resolve multiple network adapters with the same IP address segment in Linux

Article title: resolve multiple NICs in Linux with the same IP address segment. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.

Linux/documentation/ networking/ip-sysctl.txt:

Arp_filter-BOOLEAN

1-Allows you to have multiple network interfaces on the same

Subnet, and have the ARPs for each interface be answered

Based on whether or not the kernel wowould route a packet from

The ARP 'd IP out that interface (therefore you must use source

Based routing for this to work). In other words it allows control

Of which cards (usually 1) will respond to an arp request.

0-(default) The kernel can respond to arp requests with addresses

From other interfaces. This may seem wrong but it usually makes

Sense, because it increases the chance of successful communication.

IP addresses are owned by the complete host on Linux, not

Particle interfaces. Only for more complex setups like load-

Balancing, does this behaviour cause problems.

Arp_filter for the interface will be enabled if at least one

Conf/{all, interface}/arp_filter is set to TRUE,

It will be disabled otherwise

Arp_announce-INTEGER

Define different restriction levels for announcing the local

Source IP address from IP packets in ARP requests sent on

Interface:

0-(default) Use any local address, configured on any interface

1-Try to avoid local addresses that are not in the target's

Subnet for this interface. This mode is useful when target

Hosts reachable via this interface require the source IP

Address in ARP requests to be part of their logical network

Configured on the processing ing interface. When we generate

Request we will check all our subnets that include

Target IP and will preserve the source address if it is from

Such subnet. If there is no such subnet we select source

Address according to the rules for level 2.

2-Always use the best local address for this target.

In this mode we ignore the source address in the IP packet

And try to select local address that we prefer for talks

The target host. Such local address is selected by looking

For primary IP addresses on all our subnets on the outgoing

Interface that include the target IP address. If no suitable

Local address is found we select the first local address

We have on the outgoing interface or on all other interfaces,

With the hope we will receive reply for our request and

Even sometimes no matter the source IP address we announce.

The max value from conf/{all, interface}/arp_announce is used.

Increasing the restriction level gives more chance

Refreshing answer from the resolved target while decreasing

The level announces more valid sender's information.

Arp_ignore-INTEGER

Define different modes for sending replies in response

Protected Ed ARP requests that resolve local target IP addresses:

0-(default): reply for any local target IP address, configured

On any interface

1-reply only if the target IP address is local address

Configured on the incoming interface

2-reply only if the target IP address is local address

Configured on the incoming interface and both with

Sender's IP address are part from same subnet on this interface

3-do not reply for local addresses configured with scope host,

Only resolutions for global and link addresses are replied

4-7-reserved

8-do not reply for all local addresses

The max value from conf/{all, interface}/arp_ignore is used

When ARP request is already ed on the {interface}

Solution

Echo 2>/proc/sys/net/ipv4/conf/all/arp_announce

Echo 1>/proc/sys/net/ipv4/conf/all/arp_ignore

Or

Echo 1>/proc/sys/net/ipv4/conf/all/arp_filter