Abilene IPv6 Addressing Plan
The following addressing plan is based on the production allocation for
Abilene, 2001:468::/32. It still uses old terminology
such as NLA and SLA, but a rewrite to remove them is not worth the
effort.
The length of current NLAs is 16 bits. However, we will, in all
likelihood, eventually obtain a /29 sTLA which has an associated 19-bit
NLA. Once Abilene migrates to this /29, there is a very good possibility
that a mass renumbering will occur then. We didn't do so when moving
from a /35 allocation with a 13-bit NLA, though. The address format is
+----------------------------------------------------------------+
| 2001 | 4 | e | 0| NLA | SLA |
+----------------------------------------------------------------+
0 1 2 2 3 4 6
6 4 9 2 8 3
+----------------------------------------------------------------+
| Interface ID |
+----------------------------------------------------------------+
6 1
4 2
7
The five-bit field which is 0xe may look strange, but this is only
because of bit boundaries in the allocation.
To each site (6POP) on the Abilene IPv6 network, we assign a Site ID.
A site can be either an Abilene core node or a GigaPoP. With the
current allocation, the Site ID is an 8-bit value. The initial
assignment of Site IDs is
Site ID Site
0 Abilene IPv6 Core
1 Great Plains Network (GPN)
2 Pittsburgh GigaPoP (PSC)
3 Southern Crossroads (SoX)
4 Indiana GigaPoP
5 FrontRange GigaPoP
30 (Reserved)
31 (Reserved)
Abilene peer networks are assigned a Peer ID. One should be assigned
even if the connection between and the peer network is numbered out of
the peer's address space.
All nodes in the core share a Site ID of 0. They are however
assigned Core IDs as follows (this table is normative)
Core ID Router
0 0x0 (Reserved)
1 0x1 ATLA-GSR Atlanta (Cisco 12008)
2 0x2 CHIN-GSR Chicago (Cisco 12008)
3 0x3 CLEV-GSR Cleveland (Cisco 12008)
4 0x4 DNVR-GSR Denver (Cisco 12008)
5 0x5 HSTN-GSR Houston (Cisco 12008)
6 0x6 IPLS-GSR Indianapolis (Cisco 12008)
7 0x7 KSCY-GSR Kansas City (Cisco 12008)
8 0x8 LOSA-GSR Los Angeles (Cisco 12008)
9 0x9 MIX-GSR Multicast Exchange (Cisco 12008)
10 0xa NYCM-GSR New York (Cisco 12008)
11 0xb SNVA-GSR Sunnyvale (Cisco 12008)
12 0xc STTL-GSR Seattle (Cisco 12008)
13 0xd WASH-GSR Washington (Cisco 12008)
14 0xe ATLA Atlanta (Juniper T640)
15 0xf CHIN Chicago (Juniper T640)
16 0x10 DNVR Denver (Juniper T640)
17 0x11 HSTN Houston (Juniper T640)
18 0x12 IPLS Indianapolis (Juniper T640)
19 0x13 KSCY Kansas City (Juniper T640)
20 0x14 LOSA Los Angeles (Juniper T640)
21 0x15 NYCM New York (Juniper T640)
22 0x16 SNVA Sunnyvale (Juniper T640)
23 0x17 STTL Seattle (Juniper T640)
24 0x18 WASH Washington (Juniper T640)
25 0x19 ATLA-M5 Atlanta (Juniper M5)
26 0x1a KSCY-M5 Kansas City (Juniper M5)
27 0x1b LOSA-M5 Los Angeles (Juniper M5)
28 0x1c 6EAST Eastern Tunnel Terminating Router (Cisco 7206)
29 0x1d 6PLAINS Great Plains Tunnel Terminating Router (Cisco 7206)
30 0x1e 6MOUNT Mountain Tunnel Terminating Router (Cisco 7206)
31 0x1f 6WEST Western Tunnel Terminating Router (Cisco 7206)
255 0xff (Reserved)
We divide the 16-bit NLA as follows
+-----------------------------+
| NLA1 | R | NLA2 |
+-----------------------------+
0 8 11 15
where
NLA1 (8 bits) identifies the 6POP (the Site ID) and
R (2 bits) (Reserved)
NLA2 (6 bits) is assigned by the entity controlling NLA1.
Very early versions of this addressing plan specifed a left-to-right
assignment of bits in the NLA1 field (following Marc Blanchet's
Internet Draft). Given that it is likely that we would upgrade from
a /35 to a /32 to a /29 before we run out of bits in the NLA, there is
no need for unconventional bit layout.
An NLA1 value of 31 (0x1f) indicates that NLA2 contains an ID for an
end site connecting directly to Abilene, rather than through a
GigaPoP. The values for such an NLA2, designated a Direct ID, are to
be specified.
For the initial assignments we have
Site NLA1 Prefix
Abilene IPv6 Core 00000000 2001:0468:0000::/40
Great Plains Network 00000001 2001:0468:0100::/40
Pittsburgh GigaPoP 00000010 2001:0468:0200::/40
Southern Crossroads 00000011 2001:0468:0300::/40
Indiana GigaPoP 00000100 2001:0468:0400::/40
FrontRange GigaPoP 00000101 2001:0468:0500::/40
Address prefixes for use within a core 6POP are formed by setting the
NLA2 field to the Core ID of the node. For example, the prefix for
addresses internal to the Indianapolis Cisco 12008 core node would be
2001:0468:0006::/48.
Point-to-point connections between 6POPs are allocated subnets of length
/64. These come from the address block reserved for the Abilene core.
The high-order part is 2001:468::/40. The next 24 bits
are formed as follows (a rather complicated mechanism, but done to
preserve compatability with existing allocations):
+----------------------------------------------+
| SH | DH | S | SL | D | DL |
+----------------------------------------------+
0 4 8 10 16 18 23
where SRC is the Core, Site, Direct or Peer ID (as
appropriate) of the source and DST fills the same
role for the destination and
SH (4 bits) 0xf xor SRC<0:1>.
DH (4 bits) 0xf xor DST<0:1>.
S (2 bits) S=0 => the SRC field contains a Core ID;
S=1 => the SRC field contains a Site ID;
S=2 => the SRC field contains a Direct ID.
S=3 => the SRC field contains a Peer ID.
SL (6 bits) The low-order six bits of the source ID (SRC<2:7>).
D (2 bits) D=0 => the DST field contains a Core ID;
D=1 => the DST field contains a Site ID;
D=2 => the DST field contains a Direct ID.
D=3 => the DST field contains a Peer ID.
DL (6 bits) The low-order six bits of the destination ID (DST<2:7>).
By convention, the source of the connection is the endpoint with the
lower-numbered ID, with Core ID < Site ID < Direct ID < Peer ID.
Some examples of prefixes from which point-to-point connections are
addressed:
Indianapolis 12008 (Core ID=6) <-> PSC (Site ID=2)
2001:0468:00ff:0642::/64
Kansas City T640 (Core ID=19) <-> GPN (Site ID=1)
2001:0468:00ff:1341::/64
New York T640 (Core ID=21) <-> SOX (Site ID=3)
2001:0468:00ff:1543::/64
Indianapolis T640 (Core ID=18) <-> Kansas City (Core ID=19)
2001:0468:00ff:1213::/64
GPN (Site ID=1) <-> PSC (Site ID=2)
2001:0468:00ff:4142::/64
GigaPoPs are encouraged to adopt a consistent policy for address
allocation. As an example, the six-bit NLA2 field could be allocated
as follows:
NLA2 Use
0 GigaPoP internal
1
.
. Campuses
.
62
63 Point-to-point connections
Point-to-point connections might have addresses of the form
2001:0468:<xx>3f:<ss><dd>::/64
where <xx> is the Site ID, <ss> the NLA2 of the source site and <dd> the NLA2 of the destination site.
There is a need for the uniform treatment of the SLA field across all
core nodes.
