Necessary shibboleth2.xml changes for multiple frontends

<SPConfig xmlns="urn:mace:shibboleth:3.0:native:sp:config"
    xmlns:conf="urn:mace:shibboleth:3.0:native:sp:config"
    clockSkew="180">

    <OutOfProcess tranLogFormat="%u|%s|%IDP|%i|%ac|%t|%attr|%n|%b|%E|%S|%SS|%L|%UA|%a">
        <Extensions>
            <Library path="memcache-store.so" fatal="true"/>
        </Extensions>
    </OutOfProcess>

    <StorageService type="MEMCACHE" id="mc" prefix="shib:">
        <Hosts>
            <host>:11211
        </Hosts>
    </StorageService>

    <StorageService type="MEMCACHE" id="mc-ctx" prefix="shib:" buildMap="1">
        <Hosts>
            <host>:11211
        </Hosts>
    </StorageService>

... The usual shibboleth2.xml from here