Network Working Group J. T. Hao
Internet-Draft R. Huang
Intended status: Informational L. Andersson
Expires: January 2, 2015 M. Chen
Huawei Technologies Co., Ltd
July 1, 2014
Architecture of MPLS/IP Network with Hardened Pipes
draft-hao-mpls-ip-hard-pipe-00.txt
Abstract
This document is intended to become an Informational RFC on the
independent stream. The document does not specify any new protocol
or procedures. It does explain how MPLS standards been implemented,
deployed and operated to meet the requirements from operators that
offer traditional Virtual Leased Line services.
This document introduces the concept of "Hard Pipes", a Hard Pipe is
an MPLS Label Switched Path (LSP) or a Pseudowire (PW) with a
bandwidth that is guaranteed and can neither be exceeded nor
infringed upon.
This document describes an MPLS/IP network that has an infrastructure
that can be separated into two or more strata. For the
implementation described in this document the infrastructure has been
separated into two strata. One for the 'Hard Pipes', called the
'Hard Pipe Stratum". And one for the normal IP/MPLS traffic - called
the 'Normal IP/MPLS stratum'.
The Hard Pipe stratum does not use statistical multiplexing, for the
LSPs and PWs setup within this stratum the bandwidth are guaranteed
end to end.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 2, 2015.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
2. The strata network . . . . . . . . . . . . . . . . . . . . . 4
2.1. The Physical Network . . . . . . . . . . . . . . . . . . 4
2.2. The Hard Pipe stratum . . . . . . . . . . . . . . . . . . 5
2.3. The Normal IP/MPLS stratum . . . . . . . . . . . . . . . 6
2.4. Stratum Networks . . . . . . . . . . . . . . . . . . . . 7
3. Configuring the Leased Lines in Hard Pipe Stratum . . . . . . 7
4. Efficient State Management . . . . . . . . . . . . . . . . . 8
4.1. State in the Forwarding Plane . . . . . . . . . . . . . . 8
4.2. State in the NMS . . . . . . . . . . . . . . . . . . . . 9
4.3. Annotations for Configuring Leased Lines . . . . . . . . 9
5. Setting Up Leased Lines . . . . . . . . . . . . . . . . . . . 11
6. Leased Line protection . . . . . . . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
10. Informative References . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
IP leased line services and Time Division Multiplex (TDM) leased line
services are commonly offered by operators worldwide.
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There are customers, e.g. many enterprises, that insist on TDM leased
line services. They do so regardless of that the same operators
often offer IP leased line services to a lower price and with a
guaranteed bandwidth.
Today we see a trend that the TDM networks gradually carries less and
less traffic, and many operators want to shut down their TDM networks
to save cost.
The operators and vendors that built and deployed the Hard Pipe
service described in this document did so recognizing the trends
outlined above. A way to introduce leased line service with the same
characteristics as TDM leased line services in IP/MPLS networks was
created.
The solution soon to be deployed has an Ethernet infrastructure,
which has been split into two parallel logical networks - two
parallel strata. The first stratum - the Hard Pipe stratum - does
not use statistical multiplexing, and bandwidth is guaranteed end to
end. The second stratum - Normal IP/MPLS stratum - works as a normal
IP/MPLS network. The two strata share the same physical network,
i.e. routers and links. The routers will handle the traffic
belonging to one stratum different from how traffic the other stratum
is handled.
The reader of this document is assumed to be familiar with RFC 3031
[RFC3031] and RFC 5921 [RFC5921].
1.1. Scope
This document has the following purposes:
o To introduce a two strata MPLS/IP network, the purpose of one of
the strata is to provide capabilities for services that are from a
customer's point of view functionally identical to TDM like leased
lines.
o To indicate how a router differentiates the traffic of the two
strata.
1.2. Abbreviations
CC, Continuity Check
CV, Connection Verification
L-label, Leased Line label
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LSR, Label Switching Router
MPLS-TP, MPLS Transport Profile
NMS, Network Management System
OAM, Operation, Administration and Maintenance
P, Provider Router
PE, Provider Edge Router
PW, Pseudowire
T-label, Tunnel label
TDM, Time Division Multiplexing
2. The strata network
The concept of stratified or strata networks has been around for some
time. It has come to have different meaning in different contexts.
The way we use the concept is that we logically assign certain
characteristics to part of the network. The part of the network that
has the special characteristics form one stratum and the "reminder" a
second stratum. . The network described in this document uses a
single link layer technology, Ethernet.
In many cases, a whole physical interface is assigned to hard
stratum. Especially in the scenario that there are many physical
links between two nodes.
2.1. The Physical Network
Consider a network with 10 routers and all the links between are 10G
Ethernet, such as shown in Figure 1. This is the network topology
we've used for this model, and also (with topology variations) in our
first deployment.
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+---+ 10G +---+ 10G +---+ 10G +---+
+---| B |-----------| C |-----------| D |----------| E |---+
10G | +---+ +---+ +---+ +---+ | 10G
| | | | | |
+---+ | 10G 10G | 10G | 10G | +---+
--| F | | | | | | G |--
+---+ | | | | +---+
| | | | | |
10G | +---+ +---+ +---+ +---+ | 10G
+---| H |-----------| J |-----------| K |----------| L |---+
+---+ 10G +---+ 10G +---+ 10G +---+
Figure 1
In this document we use the term traffic matrix or estimated traffic
matrix to indicate an estimate of how much traffic that will flow
between the ingress and egress (PE) nodes translated into how much
bandwidth is needed per link in the Hard Pipe stratum.
2.2. The Hard Pipe stratum
We now wish to to define a Hard Pipe stratum, i.e. a part of the
network that treat all packets without introducing any delay.
Starting from an estimated traffic matrix it is possible reserve
bandwidth on the links of the Ethernet Link Layer network for the
Hard Pipes.
Note that the implication is that he normal traffic get the remainder
of the available bandwidth. Thus the link layer network will be
split into two logical networks, or two strata. One stratum to be
used for the hardened pipe network, the other for the 'normal' IP and
MPLS traffic. This is shown in Figure 2 and Figure 3.
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The Hard Pipe Stratum:
+---+ 2G +---+ +---+
+---| B |-----------| C | | E |---+
1G | +---+ +---+ +---+ | 2G
| | | |
+---+ 2G | 1G | +---+
--| F | | | | G |--
+---+ | | +---+
| | | |
1G | +---+ +---+ +---+ +---+ | 2G
+---| H |-----------| J |-----------| K |----------| L |---+
+---+ 2G +---+ 4G +---+ 4G +---+
Figure 2
It is worth noting that even if the figures in this document are
drawn to indicate "bandwidth on the link", the only bandwidth
information that the nodes have available is the bandwidth assigned
to the Hard Pipe stratum and the Normal IP/MPLS stratum. All other
information is kept on the NMS. The NMS keeps a global bandwidth
resource table for the Hard Pipe stratum.
2.3. The Normal IP/MPLS stratum
Given the starting point the physical network in Figure 1 and the
Hard Pipe stratum in Figure 2, the Normal IP/MPLS stratum will look
as in Figure 3:
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The Normal IP/MPLS Stratum:
+---+ 8G +---+ 10G +---+ 10G +---+
+---| B |-----------| C |-----------| D |----------| E |---+
9G | +---+ +---+ +---+ +---+ | 8G
| | | | | |
+---+ | 10G 8G | 10G | 9G | +---+
--| F | | | | | | G |--
+---+ | | | | +---+
| | | | | |
9G | +---+ +---+ +---+ +---+ | 9G
+---| H |-----------| J |-----------| K |----------| L |---+
+---+ 8G +---+ 6G +---+ 6G +---+
Figure 3
2.4. Stratum Networks
Stratum networks as we use the concept can be seen as two basically
parallel logical networks with strictly separated resources. Traffic
sent over one stratum network can not infringe on traffic in the
other stratum network.
In the case described here, all the traffic in the Hard Pipe stratum
is MPLS-encapsulated. A number of the labels have been set aside so
other applications can't allocate them and so the routers recognize
them as belonging to the Hard Pipe application.
3. Configuring the Leased Lines in Hard Pipe Stratum
o When an leased line is set up it is first checked if there is a
path the matches the criteria (e.g. bandwidth) for the requested
leased line.
* if such a path does exist, it is checked if there is a matching
MPLS tunnel available over that path.
+ if such a tunnel exists, it is used to establish the leased
line by adding L-labels that are local to the ingress and
egress LSRs.
At the same time the available bandwidth in the Hard Pipe
stratum is decremented by the bandwidth that is needed for
the leased line for every hop across this stratum in the
global resource table (for the Hard Pipe stratum).
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+ if such a tunnel does not exist, it can be established so
that the leased line can be set up as above.
* If the path does not exist (not enough bandwidth in Hard Pipe
stratum for the leased line), available bandwidth on the links
is checked to see if the stratum can be expanded to accommodate
such a path.
+ If the Hard Pipe stratum can expanded, this is done and the
tunnel for the leased line is established as described
above.
It is likely that modification of the Hard Pipe stratum may
have implication that goes well outside the Leased Line
service, and it is currently not viewed as a fully automated
operation.
+ If it is not possible to expand the Hard Pipe stratum to
accommodate the new path, set up of the leased line will
need to be declined.
Thus, given the existing of a viable Hard Pipe stratum, Leased Lines
are configured in two very simple steps. First, establish a hop-by-
hop tunnel (T-labels), and second configure the leased lines
(L-labels). The T-labels need to be configured on both PE and P
routers, while L-Labels only need to be configured on the PE routers.
Note that L labels may be used for normal IP service [RFC3031] , for
BGP/MPLS VPNs [RFC4364] or for PWs [RFC3985].
4. Efficient State Management
The system as described here generates a very small amount of state,
and most of it is kept in the NMS.
4.1. State in the Forwarding Plane
The only configured information that are actually kept on the LSRs
are
o the information needed for the label swapping procedures, i.e.
incoming label to outgoing label and port, and whether the label
belongs to the set of labels that are set aside for the Hard Pipe
stratum tunnels.
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o the bandwidth available for the Hard Pipe stratum and the Normal
IP/MPLS stratum
4.2. State in the NMS
The following state needs to be kept in the NMS
o the topology and bandwidth resources available in the Hard Pipe
network, see Figure 2.
o the total and available bandwidth per link in the Hard Pipe
network see Figure 4.
o the tunnel label mappings (T-labels) see Figure 5.
o the Leased Line label mappings (L-labels) see Figure 6.
o the reserved bandwidth, as well as other constraints and the path
per Leased Line (L-labels)
4.3. Annotations for Configuring Leased Lines
The annotations given below are not a programming guideline or an
indication how this architecture could be implemented. It is rather
an indication of how much data that needs to be saved for each
stratum and leased line, as well as where this data could be stored.
Consider the Hard Pipe stratum as it has been outline in Figure 2,
actually there is some additional information related to the Hard
Pipe Stratum that not is shown in the figure.
Looking explicitly on the link between LSR J and K we find:
+---+ +---+ +---+ +---+
---| H |-----------| J |-----------| K |----------| L |---
+---+ +---+ +---+ +---+
[4,0]G
Figure 4
The annotation [4,0]G means that the bandwidth on the link between J
and K there are 4G allocated to the stratum and of these 0G has been
allocated to a service.
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If we were to allocate two tunnels labels from the labels that has
been configured to work within the Hard Pipe stratum the resource
view would look like this:
+---+ +---+ +---+ +---+
---| H |-----------| J |-----------| K |----------| L |---
+---+ +---+ +---+ +---+
[4,0]G T1 ,T2
Figure 5
Note that allocating the tunnel labels does not reserve bandwidth for
the tunnel from the Hard Pipe stratum.
When the leased line labels are assigned this will consume bandwidth,
so we need to keep track of the bandwidth per leased line and the
total of bandwidth allocated from the Hard Pipe stratum.
The annotation could look like this:
+---+ +---+ +---+ +---+
---| H |-----------| J |-----------| K |----------| L |---
+---+ +---+ +---+ +---+
[4,1.5]G, T1, L1 [.5], L2 [.5], T2, L1 [.5]
Figure 6
The line [4,1.5]G, T1, L1 [.5], L2 [.5], T2, L1 [.5] would be
interpreted as:
The Hard Pipe Stratum link between nodes J and K has 4 G bandwidth
allocated; of the total bandwidth 1.5 G are allocated for Leased
Lines. Tunnel label T1, carries two Leased Lines, each of 0.5G and
tunnel label T2 carries a third Leased Line of 0.5G.
Note that it is not necessary to keep this information in the nodes,
it is held within the NMS, it is also strictly not necessary to keep
the bandwidth per leased line, but some operations are simplified
(e.g. removing a leased line) if this is done.
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5. Setting Up Leased Lines
Consider that the case where an operator want to set up a Leased Line
of 0.4G from F to G in the Hard Pipe stratum in Figure 2.
Since there are no other constraints than bandwidth and ingress and
egress PEs, the shortest path will be chosen. A tunnel will be
configure from F to G over the following nodes. F, H, J, K, L and G,
and a Leased Line label (a) will be configured on F and G, and the
available resources recalculated.
A second leased line of 0.3G between the same PEs is easily configure
by adding a new Leased Line label (b) at the ingress and egress PEs.
After these operations a view of the Hard Pipe stratum resources
would look like this:
The Hard Pipe Stratum:
+---+ 2G +---+ +---+
+---| B |-----------| C | | E |---+
1G | +---+ +---+ +---+ | 2G
| | | |
+---+ 2G | 1G | +---+
--| F | | | | G |--
+---+ | | +---+
| | | |
.3G | +---+ +---+ +---+ +---+ | 1.3G
+---| H |-----------| J |-----------| K |----------| L |---+
+---+ 1.3G +---+ 3.3G +---+ 3.3G +---+
Figure 7
If the operator now wishes to establish a new leased line with the
criteria that it should originate from F and terminate at G, have
0.4G bandwidth and pass through node E, analysis of the Hard Pipe
stratum (after establishing the first two listed lines) and the
criteria for the new leased line would give the following;
o the existing tunnel cannot be used, since it does not pass through
E; a new tunnel need to be established.
o the hop from F to H cannot be used since the available bandwidth
is insufficient.
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o the tunnel will be set up from F, to B, C, J, K, L, E (the
criteria to pass through E) and to G.
A new L-label (c) to be carried over T2 will be configured on F and
G, and the available resources of the Hard Pipe stratum will be
recalculated.
6. Leased Line protection
This leased line service uses the MPLS Transport Profile (MPLS-TP)
line protection as it is defined in RFC 6378 [RFC6378], updated as
specified in draft-ietf-mpls-tp-psc-itu [I-D.ietf-mpls-tp-psc-itu]
and draft-ietf-mpls-psc-updates [I-D.ietf-mpls-psc-updates]
The Connection Verification (CV) and Continuity Check (CC) are run
over the tunnels, i.e. the entire tunnel is as a whole.
In general all of the MPLS-TP Operation, Administration and
Maintenance (OAM), as defined in RFC 6371 [RFC6371] is applicable.
7. Security Considerations
The security considerations as defined in RFC 5920 "Security
Framework for MPLS and GMPLS Networks" [RFC5920] and RFC RFC 6941
"MPLS Transport Profile (MPLS-TP) Security Framework" [RFC6941] apply
to this document.
8. IANA Considerations
There are no requests for IANA actions in this document.
Note to the RFC Editor, this section may be removed before
publication.
9. Acknowledgements
The authors want to thank Andy Malis for detailed technical and
language review and for valuable comments.
10. Informative References
[I-D.ietf-mpls-psc-updates]
Osborne, E., "Updates to MPLS Transport Profile Linear
Protection", draft-ietf-mpls-psc-updates-06 (work in
progress), May 2014.
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[I-D.ietf-mpls-tp-psc-itu]
Ryoo, J., Gray, E., Helvoort, H., D'Alessandro, A.,
Cheung, T., and E. Osborne, "MPLS Transport Profile (MPLS-
TP) Linear Protection to Match the Operational
Expectations of SDH, OTN and Ethernet Transport Network
Operators", draft-ietf-mpls-tp-psc-itu-04 (work in
progress), March 2014.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, January 2001.
[RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-
Edge (PWE3) Architecture", RFC 3985, March 2005.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
[RFC5921] Bocci, M., Bryant, S., Frost, D., Levrau, L., and L.
Berger, "A Framework for MPLS in Transport Networks", RFC
5921, July 2010.
[RFC6371] Busi, I. and D. Allan, "Operations, Administration, and
Maintenance Framework for MPLS-Based Transport Networks",
RFC 6371, September 2011.
[RFC6378] Weingarten, Y., Bryant, S., Osborne, E., Sprecher, N., and
A. Fulignoli, "MPLS Transport Profile (MPLS-TP) Linear
Protection", RFC 6378, October 2011.
[RFC6941] Fang, L., Niven-Jenkins, B., Mansfield, S., and R.
Graveman, "MPLS Transport Profile (MPLS-TP) Security
Framework", RFC 6941, April 2013.
Authors' Addresses
JiangTao Hao
Huawei Technologies Co., Ltd
Q13 Huawei Campus
No. 156 Beiqing Road
Hai-dian District
Beijing 100095
China
Email: haojiangtao@huawei.com
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River Huang
Huawei Technologies Co., Ltd
Q13 Huawei Campus
No. 156 Beiqing Road
Hai-dian District
Beijing 100095
China
Email: river.huang@huawei.com
Loa Andersson
Huawei Technologies Co., Ltd
Stockholm
Sweden
Email: loa@mail01.huawei.com
Mach Chen
Huawei Technologies Co., Ltd
Q13 Huawei Campus
No. 156 Beiqing Road
Hai-dian District
Beijing 100095
China
Email: mach.chen@huawei.com
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