I tried IPv6 support in Amazon EC2 VPC. Amazon EC2 VPC uses RA and DHCPv6 for IPv6 addressing.

Problem

AFAIK, a EC2 instance receives an RA message with manged flag, then it sends a DHCPv6 solicit message to ff02::1:2. DHCPv6 server in VPC is expected to respond to solicit massages.

In case of dhclient, everything works well. But in case of systemd-networkd (or dhcpcd), it seems that DHCPv6 server ignores solicit messages (that is, no DHCPv6 advertise message appears in packets captured by tcpdump)

Environment

• Linux (coreos 1339.0.0, kernel 4.10.1)
• systemd 231
• dhcpcd 6.11.5 (by docker container with host-network and privileged mode)
• dhclient 4.3.5 (by docker container with host-network and privileged mode)

My suspicion

DHCPv6 solicit messages sent by systemd-networkd and dhcpcd have rapid-commit option. On the other hand, those sent by dhclient do not have rapid-commit option. The presence of that option is the most notable difference I've found in the solicit messages from dhclient and the others.

Question

In case of systemd-networkd (or dhcpcd), how to disable rapid-commit option ? I want to use systemd-networkd for network management.

I want to test Ceph (a distributed network storage and file system) on some EC2 hosts which is derived from Amazon Linux AMI (amzn-ami-2011.09.2.x86_64-ebs).

The kernel version is 3.2 and btrfs is enabled. But kernel config options related to Ceph (CONFIG_CEPH_FS and CONFIG_BLK_DEV_RBD) seems to be disabled.

I have to make a new kernel and register it to amazon ? Or, does someone know more easy way ?

My ISP has just started IPv4/IPv6 dual stack service. In order to connect IPv4/IPv6 internet, almost all users usually use a CPE leased by the ISP. But I want to use my Linux router instead of such CPE, because my router has so many roles(a lot of iptables rules and 3 Ethernet interfaces, http reverse proxy, http cache, memcached, smtp/pop server and DNS proxy). I want to let it to be an IPv4/IPv6 dual stack router.

My router

• CentOS6.0 i686
• eth0 for WAN
• eth1,2 for LAN
• ISC dhcp(version 4.1.1) installed by "# yum install dhcp" from CentOS-updates repo
• radvd(version 1.6) installed by "# yum install radvd" from CentOS-base repo
• [EDIT] The reason why I use ISC dhclient is that my router has to send a DHCPv6 option 16 (Vendor class) in its solicit and request messages, in order to get vendor-specific-information option which includes some ISP-specific informations(SIP phone number, firmware server address). I know how to set option 16 in ISC dhclient, but don't know it in WIDE-dhcpv6. And I can not find such settings as "id-assoc" in ISC dhclient.

My goal

• /48 prefix is delegated to DHCPv6-PD(DHCPv6 Prefix Delegation) client(dhclient) on eth0.
• An IPv6 default route is set toward to ISP. I have to consider ISP's DHCPv6 server's link-local address as a default route.
• One /64 subnet and one global address (which are in the delegated prefix) are assigned to each LAN I/F(eth1/eth2).
• radvd on eth1 and eth2 announces RA based on the assigned /64 subnet.
• dhcpd6 on eth1 and eth2 announces additional network information(name-servers, domain-searchlist and sip-servers-addresses) received from ISP's DHCPv6 server.

My current configuration

/etc/sysconfig/network

NETWORKING=yes
HOSTNAME=xxx.yyy.zzz

# Enable IPv6 routing and stop accept_ra/autoconf.
IPV6FORWARDING=yes

/etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE="eth0"
ONBOOT=yes
TYPE=Ethernet
BOOTPROTO=none

# Enable DHCPv6-PD client.
DHCPV6C=yes
DHCPV6C_OPTIONS="-P -cf /etc/dhcp/dhclient6.conf"

# Disable make_resolv_conf function in /sbin/dhclient-script.
PEERDNS=no

/etc/dhcp/dhclient6.conf

script "/sbin/dhclient-script";
interface "eth0" {
        send dhcp6.reconf-accept;
        also request dhcp6.vendor-opts, dhcp6.sip-servers-names, dhcp6.sip-servers-addresses, dhcp6.sntp-servers;
}

Result

After "# service network restart", DHCPv6-PD client seems to finish successfully.

lease6 {
  interface "eth0";
  ia-pd xx:xx:xx:xx {
    starts 1312464004;
    renew 7200;
    rebind 10800;
    iaprefix 24xx:xxxx:xxxx::/48 {
      starts 1312464004;
      preferred-life 12600;
      max-life 14400;
    }
  }
  option dhcp6.client-id xx:xx:xx:xx:xx:xx:xx:xx:xx:xx;
  option dhcp6.server-id xx:xx:xx:xx:xx:xx:xx:xx:xx:xx;
  option dhcp6.reconf-accept ;
  option dhcp6.sip-servers-addresses 24xx:xxxx:xxxx:xxxx::1;
  option dhcp6.name-servers 24xx:xxxx:xxxx:xxxx::3,24xx:xxxx:xxxx:b::3;
  option dhcp6.domain-search "xxx.jp.", "yyy.jp.";
  option dhcp6.sntp-servers 24xx:xxxx:xxxx:xxxx::a,24xx:xxxx:xxxx:b::b;
}

Question

DHCPv6-PD client is delegated /48 prefix successfully. But after that,

• How to set an IPv6 default route in the router's routing table ?
• How to assign a global IPv6 address and /64 subnet to each LAN I/F(eth1 and eth2) based on the delegated prefix ?
• How to trigger radvd to announce RA on each LAN I/F(eth1 and eth2) ?
• How to trigger DHCPv6 server(dhcpd6) on each LAN I/F to announce additional network information(name-servers, domain-searchlist and sip-servers-addresses) received from ISP's DHCPv6 server ?

My guess

According to "$ man dhclient" and "$ man dhclient-script", dhclient-script seems to be used to configure such settings, and it offers some hooks. But now, it does nothing for DHCPv6-PD client.

Yes, I may have to write some scripts suitable for my DHCPv6-PD environment, though I am not familiar with IPv6 network configurations. Anyone let me know the above settings in dhclient-script ? [EDIT] I want to know the practical dhclient-script.

And I worry, some special consideration should be taken. For example, because each IPv6 address has preferred/valid lifetime, when I assign a global IPv6 address to a LAN interface based on the delegated prefix, I have to assign not only an IPv6 address but also its lifetimes which must be derived from the delegated prefix's preferred/valid lifetimes ?

Also, radvd and DHCPv6 server on LAN interfaces may have to be re-configured when DHCPv6 re-configuration happens ? Which hook should be used ?

[EDIT] When DHCPv6 re-configuration happens, how to announce both new and obsolete information ? radvd automatically announce the previous prefix is obsolete? DHCPv6 server automatically announce the previous name-servers are obsolete ?