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Routing Policies for Multi-NIC Appliances - Connect IT Community | Kaseya
<main> <article class="userContent"> <h2 data-id="summary"><strong>SUMMARY</strong></h2> <p>Routing Policies for Multi-NIC Appliances</p> <h2 data-id="issue"><strong>ISSUE</strong></h2> <p></p> <p>For a deployment where a VBA (usually the Presentation and/or Management VBA) is configured to use two networks, the network active on interface eth0 will provide the default route for any address without an explicit route. As an example (Figure1):</p> <p><strong>Figure 1:<br><img alt="User-added image" src="https://us.v-cdn.net/6032361/uploads/migrated/5Q31GF15ASNU/eid-ka01w000000tcvr-feoid-00n40000002yvfa-refid-0em40000000myfs." class="embedImage-img importedEmbed-img"></img></strong></p> <p>The VmWare/Xen/HyperV host is using 10.10.95.0/24.<br>The Presentation VBA (one NIC, eth0) is using 10.10.133.0/24.<br>The Management VBA (two NICs); eth0 is using 10.10.133.0/24, eth1 is using 172.28.0.0/24.<br>Engine VBA One (one NIC, eth0) is using 10.10.133.0/24.<br>Engine VBA Two (one NIC, eth0) is using 172.28.0.0/24.</p> <p>The routing table on the Presentation and Engine One VBAs will look like the following (assuming 10.10.133.1 is the gateway):</p> <pre class="code codeBlock" spellcheck="false" tabindex="0"> Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 10.10.133.1 0.0.0.0 UG 0 0 0 eth0 10.10.133.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0</pre> <p>The routing table on the Management VBA will look as follows (using the above assumption for eth0 and 172.28.0.1 as the gateway for eth1):</p> <pre class="code codeBlock" spellcheck="false" tabindex="0"> Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 10.10.133.1 0.0.0.0 UG 0 0 0 eth0 0.0.0.0 172.28.0.1 0.0.0.0 UG 100 0 0 eth1 10.10.133.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 172.28.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 </pre> <p>or</p> <pre class="code codeBlock" spellcheck="false" tabindex="0"> Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 10.10.133.1 0.0.0.0 UG 0 0 0 eth0 10.10.133.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 172.28.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1</pre> <p>The routing table for Engine Two VBA will look as follows:</p> <pre class="code codeBlock" spellcheck="false" tabindex="0"> Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 172.28.0.1 0.0.0.0 UG 0 0 0 eth0 172.28.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 </pre> <p>Given that all Engine VBAs need network connectivity to the host (10.10.95.0/24 in the above example), the route to the host network:</p> <ul><li>must be provided by the default gateway<br><strong>or</strong> </li> <li>must be explicitly added (i.e. sudo route add -net 10.10.95.0/24 gw 172.28.0.1)</li> </ul><p>If the latter is chosen, the preferred method of persisting the route through a reboot is to include the 'route add' command in /etc/rc.local, as opposed to using the 'up' or 'post-up' stanza in /etc/network/interfaces (as shown here: <a rel="nofollow" href="/home/leaving?allowTrusted=1&target=http%3A%2F%2Fwww.cyberciti.biz%2Ffaq%2Fsetting-up-an-network-interfaces-file%2F" title="Follow">http://www.cyberciti.biz/faq/setting-up-an-network-interfaces-file/</a>).</p> </article> </main>