Shumon Huque
Networking & Telecommunications
2005-07-08 (with minor updates since then)
UPDATE: This document is historical. In 2008, the University acquired a portable (Provider-Independent) IPv6 allocation from the regional registry, ARIN 2607:f470::/32, and has developed a new addressing plan, replacing the one described here.
Penn's IPv6 address block is 2001:0468:1802::/48, which is allocated by the MAGPI GigaPoP out of it's 2001:0468:1800::/40 space. The MAGPI allocation in turn was received from it's provider, Abilene, the Internet2 backbone network. The university is contemplating applying for a portable allocation from ARIN to aid in future multi-homing.
In Penn's case, the structure of an IPv6 address looks like the following (see RFC 3513):
| 48 bits | 16 bits | 64 bits |
+-------------------------+-----------+----------------------------+
| global routing prefix | subnet ID | interface ID |
+-------------------------+-----------+----------------------------+
where the global routing prefix is 2001:0468:1802::
Certain specialized subnets do not need to consume so much space,
such as point to point links between routers, router only broadcast
networks in the core of PennNet etc. For such networks, smaller
subnet allocations of size /112 will be made from the first /64
prefix.
In addition, the first /112 sized prefix, 2001:0468:1802::/112,
is reserved for router loopback addresses and other host routes.
The remaining 65,535 /64 prefixes will be employed for general
campus subnets.
Multi-protocol BGP is used for inter-domain peering with external
IPv6 networks. At the current time, Penn's sole IPv6 peer is the
MAGPI GigaPoP. Additionally, an IPv6 Internal-BGP mesh is configured
between all the IPv6 enabled Penn core and border routers.
Address configuration for endstations is performed via stateless
address auto-configuration (RFC 2461). Stateful DHCPv6 service
may be deployed at a future date to centrally manage host address
assignments.
General Scheme
The University's /48 allocation is sufficient to number 65,536
(2 ** 16) /64 sized subnets. However, the first /64 prefix,
2001:0468:1802::/64 is treated specially.
Router Loopback Addresses
Router loopback addresses are /128 bit host routes allocated in
the prefix 2001:0468:1802::/112. Some initial allocations are:
Address Router
2001:0468:1802:0000:0000:0000:0000:0001/128 external1
2001:0468:1802:0000:0000:0000:0000:0002/128 external2
2001:0468:1802:0000:0000:0000:0000:0003/128 external3
2001:0468:1802:0000:0000:0000:0000:0004/128 vag2
2001:0468:1802:0000:0000:0000:0000:0005/128 modv2
2001:0468:1802:0000:0000:0000:0000:0006/128 huntsman2
2001:0468:1802:0000:0000:0000:0000:0007/128 nichols1
2001:0468:1802:0000:0000:0000:0000:0008/128 chnr4
2001:0468:1802:0000:0000:0000:0000:0009/128 chnr5
2001:0468:1802:0000:0000:0000:0000:000a/128 eisenschwein
2001:0468:1802:0000:0000:0000:0000:000b/128
2001:0468:1802:0000:0000:0000:0000:000d/128
Point-to-Points and other special networks
These networks typically comprise only router interfaces which
do not use EUI-64 style auto-configuration. Hence subnets smaller
than a /64 can be used. These networks are /112 sized allocations
made in the prefix 2001:0468:1802::/96. Excluding the /112 allocation
already reserved for router loopbacks, this provides the ability to
number 65,535 such networks.
Address Network
2001:0468:1802:0000:0000:0000:0001::/112 Core 1
2001:0468:1802:0000:0000:0000:0002::/112 Core 2
2001:0468:1802:0000:0000:0000:0003::/112 reserved
2001:0468:1802:0000:0000:0000:0004::/112 reserved
2001:0468:1802:0000:0000:0000:0005::/112 reserved
2001:0468:1802:0000:0000:0000:0006::/112 reserved
2001:0468:1802:0000:0000:0000:0007::/112 reserved
2001:0468:1802:0000:0000:0000:0008::/112 reserved
2001:0468:1802:0000:0000:0000:0009::/112 reserved
2001:0468:1802:0000:0000:0000:000a::/112 reserved
2001:0468:1802:0000:0000:0000:000b::/112 reserved
2001:0468:1802:0000:0000:0000:000c::/112 reserved
2001:0468:1802:0000:0000:0000:000d::/112 reserved
2001:0468:1802:0000:0000:0000:000e::/112 reserved
2001:0468:1802:0000:0000:0000:000f::/112 reserved
[p2p links:]
2001:0468:1802:0000:0000:0000:0010::/112 reserved
2001:0468:1802:0000:0000:0000:0011::/112 SEASNet link
2001:0468:1802:0000:0000:0000:0012::/112
etc etc ..
Reserved ranges
The remaining space in 2001:0468:1802::/64 is reserved for future
use.
General campus subnets
General campus subnets are all /64 sized networks excluding
the first /64 prefix, ie.
2001:0468:1802:0001::/64 ISC N&T Suite Network
2001:0468:1802:0002::/64 ISC N&T Engineering Lab
2001:0468:1802:0003::/64 Streaming Server Network
2001:0468:1802:0004::/64 ISC N&T Suite Wireless Network
2001:0468:1802:0005::/64
2001:0468:1802:0006::/64
2001:0468:1802:0007::/64
2001:0468:1802:0008::/64
2001:0468:1802:0009::/64
2001:0468:1802:000a::/64
2001:0468:1802:000b::/64
2001:0468:1802:000c::/64
2001:0468:1802:000d::/64
2001:0468:1802:000e::/64
2001:0468:1802:000f::/64
2001:0468:1802:0010::/64
2001:0468:1802:0011::/64 VoIP Servers 1
2001:0468:1802:0012::/64 VoIP Servers 2
[...]
2001:0468:1802:0101::/64 NOC1 Network
2001:0468:1802:0102::/64 NOC2 Network
2001:0468:1802:0103::/64 NOC3 Network
[...]
2001:0468:1802:ffff::/64
There is currently no general strategy of where in the range
a particular /64 subnet allocation will be made. Topological
assignment may not provide much benefit in terms of it's route
aggregation possibilities because end user subnets are increasingly
multihomed to the PennNet core.
Delegations to other departments
Large schools, institutes or departments that need their own
allocation will be provided a chunk of contiguous space from
the allocation for general campus subnets. Examples include
the Engineering school (SEASnet) and Resnet. Typically, an
aggregate advertisement for these spaces will be made at their
points of attachment to the campus routing core.
2001:0468:1802:1000::/54 Test Networks
2001:0468:1802:1400::/54 (unassigned)
2001:0468:1802:1800::/54 (unassigned)
2001:0468:1802:1c00::/54 (unassigned)
2001:0468:1802:d000::/54 ResNet
2001:0468:1802:d400::/54 (unassigned)
2001:0468:1802:d800::/54 (unassigned)
2001:0468:1802:dc00::/54 (unassigned)
2001:0468:1802:e000::/54 SEAS
2001:0468:1802:e400::/54 (unassigned)
2001:0468:1802:e800::/54 Wharton School
2001:0468:1802:ec00::/54 (unassigned)
2001:0468:1802:f000::/54 (unassigned)
2001:0468:1802:f400::/54 (unassigned)
2001:0468:1802:f800::/54 (unassigned)
2001:0468:1802:fc00::/54 (unassigned)
Routing Design
Integrated IS-IS is configured as the interior routing protocol
for IPv6. It is configured to initially carry IPv6 routes only in order
to separate it from the production IPv4 network which runs OSPF version
2. At some point in the future, IS-IS will likely be employed to route
IPv4 also. A single flat level-2 IS-IS area is initially deployed. A
multi area design will likely emerge with increased deployment of IPv6
on campus.
DNS Configuration
The Penn DNS servers support AAAA and IPv6 (long) PTR records. One
of the authoritative servers (noc3.dccs.upenn.edu) currently supports
DNS queries over IPv6 transport. An initial set of IPv6 ranges and
their associated DNS domain names have been configured in the DNS
management application (Assignments). A new third level domain,
v6.upenn.edu, has been created, for use by hosts that want
to maintain a separate domain name for their IPv6 addresses.
Future Work
References