Hi,
Techincal comments:
1. 6rd BR definition in section 3 says:
6rd Border Relay (BR) A 6rd-enabled router managed by the service
provider at the edge of a 6rd domain. The 6rd
BR router has at least one of each of the
following: an IPv4-enabled interface, a 6rd
virtual interface acting as an endpoint for the
6rd IPv6 in IPv4 tunnel, and an IPv6 interface
^^^^^^^^^^^
connected to the native IPv6 network. A 6rd BR
^^^^^^^^^^^^^^^^^^^^^^^^
may also be referred to simply as a "BR" within
the context of 6rd.
6rd BRs might not be deployed in IPv4/IPv6 border or 6rd BRs
might use virtual interface (v.s. physical interface) to connect to
a IPv6 overlay (v.s. native IPv6).
The same situation applies to 6rd CEs, e.g., a 6rd CE might be
an ISATAP router.
2. section 4 talks about 6rd delegated prefix delegation rather
than 6rd prefix delegation. Should the title be changed?
3. section 6 says 6rd addresses should be treated as native
addresses and no changes are needed for address selection.
6rd is a native-equivalent IPv6, but not native IPv6 after all.
When a customer is connected to a 6rd IPv6 and native IPv6
at the same time, (s)he might only want to use 6rd address
when (s)he communicates with hosts within the 6rd domain.
4. the 6rdPrefixLen semantics in section 7.1.1 says:
6rdPrefixLen The IPv6 Prefix length of the SP's 6rd IPv6
prefix in number of bits. For the purpose
of bounds checking by DHCP option
processing, the sum of (32 - IPv4PrefixLen)
+ 6rdPrefixLen MUST be less than or equal
^^^^^^^^^^^^^^^^^^
to 128. The 6rd implementation may further
^^^^
limit the sum of these lengths to 64.
But the last sentences in para2, sec4 says
To allow for stateless address auto-configuration on
the CE LAN Side, a 6rd delegated prefix MUST be /64 or shorter.
the sum of (32-IPv4PrefixLen)+6rdPrefixLen = size of the
6rd delegated prefix. Is it an inconsistency?
5. at the end of the section 7.2, the RIB appears as:
::/0 -> 2001:ABC0:0000:0100:: (default route)
2001:ABC0::/32 -> 6rd-virtual-interface0 (direct connect to 6rd)
2001:ABC0:6464:0100::/56 -> Null0 (delegated prefix sink route)
2001:ABC0:6464:0100::/64 -> Ethernet0 (LAN interface)
The routes are confusing. The first route indicates the next
hop whileas the rest routes indicate the coresponding interface.
Actually, the first route should have indicated 6rd-virtual-interface0
but with the specific next hop 2001:ABC0:0000:0100::
6. In section 8, you give one recommended method for NUD
between CEs and BRs, so what is recommended for NUD
between CEs and BRs?
7. It is still hard for me to get to looping issues described in
section 12, it would help if an example was there.
8. compared to 6to4 spec (rfc3056), this document does not
mention the routing exchange between CEs and BRs, especially
when anycast is not used for BR discovery. Is this the original
intention?
editorial comments:
9. the first sencence in para4, sec1:
A 6rd domain consists of 6rd Customer Edge (CE) routers and one or
more 6rd BRs.
^^^^^
I prefer "6rd Border Relay (BR) routers" instead.
10. CE IPv4 address definition in sec3:
CE IPv4 address The IPv4 address given to the CE as part of
normal IPv4 Internet access (i.e., configured
via DHCP, PPP, or otherwise). This address may
be global or private [RFC1918] within the 6rd
domain. This address is used by a 6rd CE to
create the 6rd delegated prefix as well as to
send and receive IPv4 encapsulated IPv6
^^^^^^^^^^^^^^
packets.
Should it be IPv6 encapsulated IPv4?
11. 1st sentence in sec4:
The 6rd delegated prefix for use at a customer site is created by
combining the 6rd prefix and some or all of the CE IPv4 Address.
^^^^^^
addresses.
12. the para2, sec4:
In 6to4, a similar operation is performed by incorporating an entire
IPv4 address at a fixed location within a well-known /16 IPv6 prefix.
^^^^ following
In 6rd, the IPv6 prefix as well as the position and number of bits of
the IPv4 address incorporated varies from one 6rd domain to the next.
6rd allows the SP to adjust the size of the 6rd prefix, bits used by
^how many
the 6rd mechanism, and how many bits are left to be delegated to
customer sites. To allow for stateless address auto-configuration on
the CE LAN Side, a 6rd delegated prefix MUST be /64 or shorter.
13. IID is not in right propositional to the address length in figure 1.
14. last para, sec5:
The 6rd CE and BR SHOULD support the IPv6 Subnet-Router anycast
address [RFC4291] for its own 6rd delegated prefix. This allows, for
example, IPv6 ping messages to be sent to the 6rd Virtual Interface
itself for additional troubleshooting of the internal operation of
6rd at a given CE or BR, over and above an IPv4 ping to the
^^^^^^^^^^^^^^^^^^^ ( I don't get it)
associated CE or BR IPv4 address. In the case of the BR, the IPv4
address used to calculate the 6rd delegated prefix is the configured
BR IPv4 Address.
15. para2, sec9:
IPv6 packets from a CE are encapsulated in IPv4 packets when they
leave the site via its CE WAN Side interface. The CE IPv4 address
^^^ A
MUST be configured to send and receive packets on this interface.
Thanks,
washam
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