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HSLS Protocol Capabilities & Extensibility
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The HSLS protocol is agnostic about the network layer.  That is,
it can route IPv4, IPv6, IEEE 802.3/802.11 networks. The protocol
can disseminate routes for multiple network types, simultaneously---for
example, both IPv4 and IPv6 routes.

Each HSLS router is uniquely identified by a 32-bit identifier
apart from any network numbers assigned.

The HSLS protocol is capable of carrying both IPv4 and IPv6
host- and subnet-routes, simultaneously.

The HSLS protocol uses IP multicast, link-layer multicast, or both,
to limit the recipients of broadcast HSLS messages to interested
routers.

HSLS must protect against link-state messages being endlessly
flooded by, for example, counting and limiting the number of hops
per message.

The HSLS protocol will support point-to-multipoint (ptmp),
point-to-point (ptp), and broadcast (bcast) links.  A ptp link
connects only two routers. A ptmp link connects routers on the same
subnet to one another.  A router on a ptmp subnet may or may not
be connected to every other router.  A broadcast link connects a
router to a broadcast subnet. Connectivity on the broadcast medium
is expected to be transitive. That is, bcast connections from both
router A to B and B to C imply a connection from router A to C.

The two routers on a ptp link need not belong to the same subnet:
HSLS ptp links are "unnumbered." Both routers are responsible for
sending LSAs indicating connectivity in one direction with the ptp
interface's number (ifIndex in the appropriate MIB) and the remote
router's address.

On a ptmp link, all routers belong to the same subnet. For every
different pair of neighbors, 

All routers on the same bcast link belong to the same subnet.  Each
router may assign a cost to its bcast link independently of every
other router on the same link.  That is, routers link costs for
the same bcast network need not agree.  A router may not individually
assign different costs to its neighbors on a bcast link.  The
protocol will contain provisions for efficient advertisement of
bcast links, so that O(n^2) different LSAs are not necessary to
advertise full mesh bcast connectivity for the n routers on the
link.  [OSPF's DR, BDR, and Network-LSAs may be appropriate.]

The HSLS protocol must be capable of advertising links with a "cost
vector" which describes link costs in one or more dimensions. such
as ETX, neighbors on the link, delay, and capacity. A link cost
ranges from 1 to 2^31 - 1 in every dimension.  The HSLS protocol
must label each cost-vector element with the dimension it describes.
The protocol must define how cost vectors are added and compared,
with special attention to both same-length cost vectors whose
elements come in a different order---

	v1 = [etx, delay, capacity]
	v2 = [delay, etx, capacity]

---and different-length cost vectors---

	v1 = [etx, delay, capacity]
	v2 = [etx, capacity].

The HSLS protocol must provide for authentication and confidentiality
of routing messages, without requiring greater memory & CPU resources
for the purpose than a typical handheld computer can provide.  C-U
Wireless is concerned that routers holding the same secret key can
impersonate each other; the HSLS protocol must assist routers in
detecting impersonation.  The protocol must provide for keys to be
renewed and revoked.

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