Network Working Group Peng He
Internet Draft Gregor v. Bochmann
Expires: March 2007 University of Ottawa
September 21, 2006
A Novel Framework for Inter-area MPLS Optimal Routing
draft-he-ccamp-optimal-routing-00.txt
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Abstract
We propose a novel framework for inter-area MPLS optimal routing. The
key to our proposal lies in deploying an overlaid star optical
network in the OSPF backbone area and introducing the concept of
"virtual area border routers" (v-ABRs). Compared with other
proposals, our framework can provide globally optimized inter-area
routing and has very good compatibility to existing traditional
IP/MPLS routers.
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Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119].
Table of Contents
1. Terminology....................................................2
2. Introduction...................................................3
2.1. What's The Problem........................................3
2.2. Current Approaches........................................4
3. The Novel Framework for Inter-area MPLS Optimal Routing........5
3.1. The Basic Idea............................................5
3.1.1. Overview of Agile All-Photonic Network (AAPN)........5
3.1.2. Deploying AAPN in the OSPF Backbone Area.............6
3.2. The Routing-Info Component................................7
3.3. The Path Computation Component............................8
3.4. The Signalling Component..................................8
3.4.1. Path Message in the Head-End Area....................9
3.4.2. Path Message in the Backbone Area....................9
3.4.3. Path Message in the Tail-end Area...................10
3.4.4. Resv Message........................................10
4. Further Considerations........................................11
5. Generalization of the Proposed Routing Framework..............12
6. Security Considerations.......................................13
7. IANA Considerations...........................................13
8. Conclusions...................................................13
9. Acknowledgments...............................................13
10. References...................................................14
Author's Addresses...............................................15
Intellectual Property Statement..................................15
Disclaimer of Validity...........................................16
Copyright Statement..............................................16
Acknowledgment...................................................16
1. Terminology
OSPF: Open Shortest Path First
CSPF: Constraint-based Shortest Path First
LSP: Label Switched Path
LSR: Label Switched Router
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LSDB: Link State Database
RSVP: Resource Reservation Protocol
AAPN: Agile All-Photonic Network
2. Introduction
Currently, several carriers have multi-area networks, and many other
carriers that are still using a single IGP area may have to migrate
to a multi-area environment as their network grows and approaches the
single area scalability limits [RFC4105]. Hence, it would be useful
and meaningful to extend current MPLS TE (Traffic Engineering)
capabilities across IGP areas to support inter-area resources
optimization. That is why RFC4105 [RFC4105] was recently published to
define detailed requirements for inter-area MPLS traffic engineering
and ask for solutions.
In this draft, we consider the Open Shortest Path First (OSPF)
[RFC2328, RFC3630] IP routing protocol, which is commonly used for
routing within a single administrative domain and adopted by MPLS and
GMPLS (Generalized MPLS) (with extensions).
2.1. What's The Problem
OSPF supports large networks through multiple OSPF areas: one
backbone area (Area0) surrounded by non-backbone areas. Area border
routers (ABR) are located at the border between the backbone and the
non-backbone areas.
An inter-area connection normally starts in a non-backbone area,
traverses a backbone area, and terminates in another non-backbone
area. MPLS TE mechanisms that have been deployed today by many
carriers are limited to a single IGP area and can not be expanded to
multi-areas directly. The limitation comes more from the routing and
path computation components than from the signalling component. This
is basically because the OSPF/OSPF-TE hierarchy limits topology
visibility of head-end LSRs (Label Switch Routers) to their area, and
consequently head-end LSRs can no longer run a CSPF algorithm to
compute the shortest constrained path to the tail-end, as CSPF
requires the whole topology information in order to compute an end-
to-end shortest constrained path.
For an example, Figure 1 shows a common multi-area network and we
suppose RT1 in Area1 is the source node while RT6 in Area2 is the
destination. Generally speaking, a non-backbone area (e.g., Area1 in
Figure 1) often has multiple ABRs (existing points). One ABR might be
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much closer to the destination of a requested MPLS connection than
another. Because the head-end node does not have the entire topology,
it does not know which ABR is the best choice. In Figure 1, how could
R1 choose an optimum ABR in Area1 to the destination RT6? Through
local optimization, R1 may select ABR2 to be on the path, but how
does ABR2 know what the best path is to go to RT6? Although local
optimization can be done in each of the respective areas along the
inter-area path (RT1 to RT6), the simple summation of the three local
optimizations does not necessarily lead to a global optimization.
What many carriers want is to optimize their resources as a whole.
Therefore, the question of how to implement inter-area routing with
global optimization guarantee is a key issue in inter-area traffic
engineering.
2.2. Current Approaches
Most current approaches for inter-area routing center on the "how-to"
issue, that is, how to find out an inter-area route (not optimal and
not dynamic) and how to build up this path through the inter-area
signalling process. The per-area approach uses a two-step method to
compute an inter-area route: find out a "loose inter-area route"
first through topology aggregation/abstraction, then resolve the
loose route into a strict path, area by area. Actually, this per area
approach would always lead to sub-optimal resource utilization.
Another segment approach divides an inter-area path into two
segments, one in Area1 and one in Area0 & Area2 (see Figure 1 for a
rough look). Optimal routing of the 1st segment is done first by the
head-end LSR; then based on the 1st segment, a far-end ABR (e.g.,
ABR5) computes the 2nd segment. Obviously, this approach can not
achieve global route optimization either. PCE (Path Computation
Element)-based approaches [PCE-ARC] are the only category of
approaches that can provide global optimization. But this needs
building up an independent overlay external PCE network that covers
all the areas, and defining and implementing many associated new
protocols.
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<---------Area1---------><------Area0-------><-------Area2----->
--- ---- ---- ---
|RT2|--|ABR1|-----...------|ABR4|---|RT6|
/ --- ---- ---- / --- \
/ / \
--- --- ---- ---- / \ ---
|RT1|---|RT3|---------|ABR2| ... |ABR5|-----------|RT8|
--- --- ---- ---- \ / ---
\ / \ /
\ --- --- / ---- ---- \ --- /
|RT4|----|RT5|--|ABR3|-----...------|ABR6|---|RT7|
--- --- ---- ---- ---
- ABR1, ABR2, ABR3: Area0-Area1 ABRs
- ABR4, ABR5, ABR6: Area0-Area2 ABRs
Figure 1 : A common network with multiple OSPF areas.
3. The Novel Framework for Inter-area MPLS Optimal Routing
3.1. The Basic Idea
In this draft, we propose a novel framework that deploys an overlaid
star optical network in the backbone area so as to implement global
resource optimization in an efficient and distributed manner. The
star topology can help to achieve globally-optimized routing (as
explained later), and the overlaid star can provide high reliability.
AAPN (Agile All-Photonic Networks) is a representative example of
overlaid star optical networks. Hence we use AAPN to represent
overlaid star networks in the following context of this draft.
3.1.1. Overview of Agile All-Photonic Network (AAPN)
As shown in Figure 2, an AAPN [AAPN-ARC] consists of a number of
hybrid photonic/electronic edge nodes connected together via several
(not less than two) load-balancing core nodes and optical fibers to
form an overlaid star topology. Note that there are no direct
physical links among these cores. By introducing concentrating
devices, AAPN can support up to 1024 edge nodes [AAPN-TOP]. Each core
node contains a stack of bufferless transparent photonic space
switches (one for each wavelength). A scheduler at each core node is
used to dynamically allocate timeslots over the various wavelengths
to each edge node. An edge node contains a separate buffer for the
traffic destined to each of the other edge nodes. Traffic aggregation
is performed in these buffers, where packets are collected together
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in fixed-size slots (sometimes called bursts) that are then
transmitted as single units across the AAPN via optical links. At the
destination edge node the slots are partitioned, with reassembly as
necessary, into the original packets that are sent to the outside
routers. The term "agility" in AAPN describes its ability to deploy
bandwidth on demand at fine granularity, which radically increases
network efficiency and brings to the user much higher performance at
reduced cost.
--- ---
|EN3|---|RT8|
--- ---
| |
--- | v ---
|RT1| | to CN2 /|RT4|
--- \ --- ----- --- / ---
\|EN1|------| CN1 |------|EN4|/
/ --- \ /| |\ / --- \
--- / \ / ----- \ / \ ---
|RT2|/ \/ \/ \|RT5|
--- /\ /\ / ---
/ \ ----- / \ /
--- / \| CN2 |/ \ --- /
|EN2|------| |------|EN5|
--- / --- ----- --- \
|RT3|/ | | to CN1 \ ---
--- | | ^ |RT6|
--- | | ---
|RT7| ---
--- |EN6|
---
- CN: Core Node
- EN: Edge Node
- RT: Router
Figure 2 : Agile All-Photonic Network (AAPN) Overlaid Star Topology.
3.1.2. Deploying AAPN in the OSPF Backbone Area
AAPN is more suitable to be used in multi-area network environment
due to its agility at the core and large capacity. The direct and
natural way to deploy an AAPN in the OSPF backbone area is like this:
the core nodes are located in the middle of Area0 and the edge nodes
act as ABRs at the border between Area0 and other non-backbone areas.
However, in this scheme, inter-area routing with global optimization
still can not be guaranteed. Therefore, we adopt a novel way of
deploying OSPF over an AAPN that interconnects several OSPF areas to
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provide such guarantee, as shown in Figure 3. This "overlapped" OSPF
architecture is fundamental for our inter-area MPLS optimal routing
framework. In details, our proposed framework consists of three main
components, namely the routing-info, path computation and signalling
components, as described in the following sections.
Note: due to the symmetric architecture of AAPN (see Fig. 2), we use
the "bundle" [RFC4201] concept to further reduce the overhead traffic
to the outside. That is, all the links from one edge node to the core
nodes are exported as one TE link. Similarly, the overlaid core nodes
in AAPN are, if necessary, exported as one core node, named as "the
core" (see Figure 3).
<--------------Area1-----------------><-----------Area2---------->
<---------Area0-------->
--- ---- ---- ---
|RT2|--|EN1 | |EN4 |---|RT6|
/ --- ---- \ / ---- / --- \
/ \ ------ / / \
--- --- / ---- \| THE |/ ---- / \ ---
|RT1|----|RT3|----------|EN2 |---| CORE |---|EN5 |-----------|RT8|
--- \ --- / ---- /| |\ ---- \ / ---
\ / / ------ \ \ /
\ --- --- / ---- / \ ---- \ --- /
|RT4|---|RT5|---|EN3 | |EN6 |---|RT7|
--- --- ---- ---- ---
<-------------sub-path1-------------><--------sub-path2---------->
Figure 3 : Our framework deploys AAPN as backbone area (Area0).
3.2. The Routing-Info Component
This component is responsible for the discovery of the TE topology,
which can be ensured through OSPF [RFC2328] and OSPF-TE [rfc3630]. As
shown in Figure 3, after deploying AAPN as backbone area, we further
expand the OSPF non-backbone areas a little step so that there is an
overlap between Area0 and each expanded non-backbone area. Then the
AAPN edge nodes located in the overlap (see the top of Figure for the
overlap), together with their direct TE links to the core, and the
associated part of the core, belong to both the Area0 and a non-
backbone area. In such a scenario, legacy routers in a non-backbone
area see related AAPN edge nodes as normal internal IP/MPLS routers,
see the AAPN TE links as normal internal links and see the associated
part of the core as the (only) ABR of their non-backbone area. In
other words, a legacy router sees what it can see in its area about
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the core as an ABR, which we call a virtual-ABR (v-ABR). For each
legacy router in an expanded non-backbone area, the exchange and
distribution of routing/TE information is just like in any other
standard OSPF/OSPF-TE area.
While within the Area0 (within the AAPN), the AAPN edge nodes that
belong to the same non-backbone area can be organized as a big
virtual router and one edge node in each virtual router is selected
as the head of this virtual router. Then the area-specific
reachability information is exchanged among these heads and
distributed to each edge node per area and then outside routers.
Therefore, it is the head edge node that actually performs the
functions of the virtual-ABR, that is, distributing area-specified
reachability information. Note that only the reachability (not TE)
information, which is enough for our framework, is exchanged among
virtual routers, and hence among non-backbone areas.
3.3. The Path Computation Component
In our framework, an inter-area LSP can be considered consisting of
two segments as shown in the bottom Figure 3: one in the head-end
(expanded) area (sub-path1) and one in the tail-end (expanded) area
(sub-path2). The core connects these two segments/sub-LSPs to form a
complete inter-area LSP.
The most interesting thing is that local routing optimization
(through CSPF) with both of these two sub-LSPs can lead naturally to
a globally-optimized inter-area LSP. As seen in Figure 3, this is due
to the particular star topology of the AAPN architecture and the
load-sharing core nodes that can be viewed as one single virtual
router (v-ABR) from the outside.
The local routing optimization in the head-end area can be performed
by the source LSR, which takes the TE topology and LSP constraints as
input. While in the tailend area, local routing optimization is done
by one of the edge nodes in the area (see next section for details).
Obviously, dynamic inter-area routing can be implemented in our
proposed framework.
3.4. The Signalling Component
This component is responsible for the establishment of the LSP along
the computed path. In Figure 3, consider the case that a source LSR
(RT1) in Area1 wants to set up a LSP to a destination LSR (RT8) in
Area2. RT1 must first compute an optimized path to the virtual-ABR of
Area1 (v-ABR1) through CSPF, and then signal this establishment
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request to the network. RSVP with TE extension (RSVP-TE) [RFC2205,
RFC3209] can be used as the signalling protocol.
3.4.1. Path Message in the Head-End Area
As shown in Figure 4, RT1 starts the signalling process by creating a
RSVP Path message with two objects inserted, namely LABEL_REQUEST
Object (LRO) to request a label binding for the path, and
EXPLICIT_ROUTE object(ERO) to indicate the computed explicit path
(with one sub-object per hop). However, RT1 has to use the loose ERO
sub-objects for the hops outside Area1. In Figure 3, the ERO
specifies the explicit path as RT1->RT3->EN2->v-ABR1->RT8, where RT8
is a loose ERO sub-object. Then, RT1 sends the Path message to the
next hop defined in the ERO, which is RT3.
RT3 (a non AAPN node) receives the Path message and processes it as
defined by RSVP-TE:
1. Checks the message format to make sure everything is OK,
2. Performs admission control to check the required bandwidth,
3. Stores the "path state" from the Path message in its local Path
State Block (PSB) to be used by the reverse-routing function, and
4. If successful, deletes the 1st sub-object (itself) in the ERO and
forwards the Path message according to the new 1st sub-object
(next hop) in the ERO, in our case, EN2.
3.4.2. Path Message in the Backbone Area
EN2, an AAPN edge node, receives the Path message from RT3 and checks
the contained ERO. If EN2 finds that the IP address of the 2nd sub-
object in the ERO is a v-ABR and the 3rd sub-object (with the loose
attribute) is beyond Area1, then EN2 has the task of resolving the
loose sub-object into strict ones. In our case, there is one loose
sub-object, RT8, which represents the destination of the requested
LSP. Although EN2 can not find a strict path from v-ABR1 to RT8 by
itself, it knows who can. First, by checking the inter-area
reachability information and internal parameters, EN2 finds out which
group of edge nodes (also which associated v-ABR) locates in the same
non-backbone area as RT8. In Figure 4, these are EN4, EN5 and EN6 (v-
ABR2). Second, it selects an edge node among them randomly, e.g.,
EN4. In the third step, EN2 removes the first two sub-objects (itself
and v-ABR #1) from the ERO of the original received Path message, and
inserts v-ABR2 at the top, then forwards the modified Path message to
EN4.
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When EN4 receives the Path message and finds that the 1st sub-object
in the received ERO is v-ABR2, together with a loose second sub-
object, RT8, it knows that it should find an explicit path between
these two sub-objects. As shown in Figure 3, EN4 is capable to do the
resolving work because EN4 and RT8 reside in the same expanded area,
Area2. EN4 finds the optimized explicit path v-ABR2->EN5->RT8. EN4
then replaces the ERO object in the received Path message with a new
ERO object that stores the resolved explicit route (EN5->RT8).
Finally, EN4 forwards the new modified Path message to EN5 as if it
were forwarded from EN2 by using EN2's data (IP address, etc.). We
call this process a Path message handoff. At the same time, EN5 also
sends an acknowledge message (containing the resolved path) to EN2
(Figure 5). From the above handoff process, we can see that only the
area-specific reachability (not TE) information needs to be exchanged
among areas. In our proposal, TE information is organized within each
area.
3.4.3. Path Message in the Tail-end Area
The edge node EN5 receives the Path message and believes it is from
EN2. Since all the sub-objects in the received ERO are strict, EN5
processes this Path message in a standard way, just as RT3 did in
Area1, and then forwards the processed Path message to RT8.
3.4.4. Resv Message
When the destination, RT8, gets the Path message, it responds to this
establishment request by sending a RSVP Resv message. The purpose of
this response is to have all routers along the path perform the Call
Admission Control (CAC), make the necessary bandwidth reservations
and distribute the label binding to the upstream router.
As defined in standard ESVP-TE [RFC3209], the label is distributed
using the Label Object in the Resv message. The labels sent upstream
become the output labels for the routers receiving the label object.
The label that a router issues upstream become the inbound label used
as the lookup into the hardware output tag table. The reservation-
specific information is stored in the local reservation state block
(RSB) of each router.
When the AAPN edge node EN5 receives the Resv message from downstream
(RT8), it starts internal AAPN signalling to ask the core to set-up a
connection from EN2 to EN5 (omit v-ABR1&2). If bandwidth is available
for this connection, the core informs both EN2 and EN5. EN5 then
sends a Resv message to EN1. Note that it is an internal choice of
the AAPN to select a label, for instance, a timeslot number, a
wavelength, or a normal MPLS label.
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The Resv message makes its way upstream (see Figure 4), hop by hop,
and when it reaches the source LSR, RT1, the inter-area path is set-
up as: RT1->RT3->EN2->v-ABR1->v-ABR2->EN5->RT8. Now, a globally
optimized inter-area LSP is set-up. It can be maintained and torn-
down just as any normal intra-area LSP tunnel.
<-------------Area1---------------><------------Area2---------->
<--------Area0-------->
----
|EN4 |
------ / ----
--- --- ---- | THE |/ . ---- ---
|RT1|----|RT3|----------|EN2 |---| CORE |--------|EN5 |------|RT8|
--- --- ---- | | . ---- ---
. . ------ . . .
. . . . . .
. .PATH======341=========>. . . .
t . .PATH===342=======>. . .
i . .<=================.=Hand=>. .
m . . . off . .
e . . . .PATH=343=>.
. . . . . .
. . . .<=344=RESV.
v . .<=========344=========RESV. .
.<=========344======RESV. . .
Figure 4 : Inter-area LSP Signaling Process.(34x means Section 3.4.x)
4. Further Considerations
Contrary to other inter-area proposals, our proposal can provide
globally-optimized inter-area routing and does not require any
changes on existing traditional IP/MPLS routers, hardware or
software, to implement (good backward compatibility). Furthermore,
there is no node that has global TE information. Instead, the TE
information is distributed on a per-area basis and only area-specific
reachability (not TE) information is exchanged among areas. Global
optimization is achieved through cooperation and interaction between
AAPN edge nodes in different areas (Path message handoff). In
addition, for the 2nd half of an inter-area LSP (in the tail-end
area), the optimized routing computation is done by an AAPN edge node
randomly chosen in the tail-end area. Hence, load-sharing among these
edge nodes is achieved.
Under our proposed framework, inter-area routing can be dynamic. In
addition, re-optimization of an inter-area TE LSP can also be
implemented, either locally within an area (by the head-end LSR for
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the 1st half or by an edge node for the 2nd half of LSP) or globally
by the head-end LSR (end-to-end re-optimization).
Regarding inter-area QoS, there is not much work left. Current single
area QoS mechanisms [RFC2475, RFC 3270] can be expanded directly to
multiple areas and to AAPN.
As seen in Figure 3, our proposal keeps OSPF's hierarchical structure
and just expands non-backbone areas a little. Hence the scalability
of our proposal is as good as OSPF/OSPF-TE [RFC2328, RFC3630].
Our proposed framework also supports diversely-Routing of inter-area
TE LSPs, as required in RFC4105 [RFC4105]. As shown in Figure 3,
diversely routing can be deployed in Area 1 and 2 independently and
optimally, and then the AAPN residing in the backbone area connects
them together.
5. Generalization of the Proposed Routing Framework
The routing concepts discussed in this draft are based on the
assumption that there are a number of edge nodes (that are connected
with other routers - through traditional Internet technology - and
belonging to the same OSPF area) and these edge nodes can establish
optical connections between one another in an agile manner and can
adjust the bandwidth of each connection in an agile manner according
to the varying bandwidth that is required by the IP traffic. We think
any agile optical switching technology (burst switching, TDM (Time-
Division-Multiplexing), or routed wavelength (with less bandwidth
flexibility)) may be used.
Our proposal is not limited to AAPNs, it is actually applicable in a
much larger context. The fundamental ideas abstracted from our
proposal are: (1) a "load-symmetrical" network (optical mostly) as
backbone, (2) overlap between backbone and non-backbone areas, and
(3) virtual-ABR. A load-symmetrical optical network is a network that
can provide one or several optical connections for each edge node
pair (source-destination pair) and the load among the several optical
connections of each edge node pair is balanced. Hence the "bundle"
concept [5] can be used and a single core can represent the optical
network topology.
Note that "load-symmetrical" does not mean the loads among any
distinct edge node pairs are balanced; it only refers to the load-
balancing within the connections of one edge node pair. Load
symmetrical networks do not need to have a symmetrical physical
network topology, although a symmetrical physical network topology
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(such as AAPN] and PON (Passive Optical Networks)) can be made load-
symmetrical easily.
6. Security Considerations
This document does not introduce new security issues beyond those
inherent in MPLS TE [RFC3209, rfc3630].
7. IANA Considerations
This informational document makes no requests for IANA action.
8. Conclusions
Based on deploying a load-symmetrical network (such as an overlaid
star optical network (AAPN)) in multi-area networks, we propose a
novel framework that aims to implement optimal inter-area MPLS
routing.
Compared with other inter-area routing proposals, our proposal has
two distinguishing characteristics:
1. Our proposal can provide globally-optimized inter-area routing;
2. There will be no change, hardware or software, on existing
traditional IP/MPLS routers in the peripheral OSPF areas to
implement our proposal.
Furthermore, our proposal is not limited to AAPNs; it is actually
applicable to any load-symmetrical (optical) network with arbitrary
physical network topology. Indeed, our proposal can be considered as
a highly competitive candidate that has the potential to become a
total solution to Inter-area MPLS Traffic Engineering [RFC4105].
9. Acknowledgments
This work was supported by the Natural Sciences and Engineering
Research Council (NSERC) of Canada and industrial and government
partners, through the Agile All-Photonic Networks (AAPN) Research
Network. This work is part of an AAPN Partnered Research Project
sponsored by TELUS. The authors thank Rainer Iraschko for useful
discussions.
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10. References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC2328] J. Moy, "OSPF Version 2", RFC 2328, April, 1998.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated Service",
RFC 2475, December 1998.
[RFC3209] Awduche, D., et al. "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December, 2001.
[RFC3270] Le Faucheur, F., Wu, L., Davie, B., Davari, S.,Vaananen,
P., Krishnan, R., Cheval, P., and J. Heinanen, "Multi-
Protocol Label Switching (MPLS) Support of Differentiated
Services", RFC 3270, May 2002.
[RFC3630] Katz, D., Yeung, D., Kompella, K., "Traffic Engineering
Extensions to OSPF Version 2", RFC 3630, September, 2003.
[RFC4105] Le Roux, et al., "Requirements for Inter-Area MPLS Traffic
Engineering", RFC 4105, June 2005.
[RFC4201] K. Kompella et al. "Link Bundling in MPLS Traffic
Engineering (TE)" RFC 4201, October, 2005.
[PCE-ARC] Farrel, A., "A Path Computation Element (PCE) Based
Architecture", draft-ietf-pce-architecture-04 (work in
progress), January 2006.
[AAPN-ARC]G. v. Bochmann, M.J. Coates, T. Hall, L. Mason, R. Vickers
and O. Yang, "The Agile All-Photonic Network: An
architectural outline", Proc. Queen's University, Biennial
Symposium on Communications, 2004, pp.217-218.
[AAPN-TOP]L.G. Mason, A. Vinokurov, N. Zhao and D. Plant,
"Topological Design and Dimensioning of Agile All Photonic
Networks", Computer Networks: The International Journal of
Computer and Telecommunications Networking, Volume 50,
Issue 2(February 2006), Pages: 268 - 287, 2006.
He and Bochmann Expires March 21, 2007 [Page 14]
Internet-Draft Inter-area Optimal Routing Framework September 2006
Author's Addresses
Peng He
School of Information Technology and Engineering (SITE)
University of Ottawa
800 King Edward Avenue
Ottawa, Ontario
K1N 6N5 Canada
Phone: 1-613-5625800 ext. 2191
Email: penghe@site.uottawa.ca
Gregor v. Bochmann
School of Information Technology and Engineering (SITE)
University of Ottawa
800 King Edward Avenue
Ottawa, Ontario
K1N 6N5 Canada
Phone: 1-613-5625800 ext. 6205
Email: bochmann@site.uOttawa.ca
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He and Bochmann Expires March 21, 2007 [Page 15]
Internet-Draft Inter-area Optimal Routing Framework September 2006
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He and Bochmann Expires March 21, 2007 [Page 16]