I think MOBIKE [1][2] should solve this, roaming between different networks.<p>[1] <a href="https:&#x2F;&#x2F;wiki.strongswan.org&#x2F;projects&#x2F;strongswan&#x2F;wiki&#x2F;MobIke" rel="nofollow">https:&#x2F;&#x2F;wiki.strongswan.org&#x2F;projects&#x2F;strongswan&#x2F;wiki&#x2F;MobIke</a><p>[2] <a href="https:&#x2F;&#x2F;tools.ietf.org&#x2F;html&#x2F;rfc4555" rel="nofollow">https:&#x2F;&#x2F;tools.ietf.org&#x2F;html&#x2F;rfc4555</a>