Internet DRAFT - draft-fujita-ospf-te-summary
draft-fujita-ospf-te-summary
Network Working Group Norihito Fujita
Internet Draft Atsushi Iwata
<draft-fujita-ospf-te-summary-00.txt> NEC Corporation
Expires in six months
March 2000
Traffic Engineering Extensions to OSPF Summary LSA
<draft-fujita-ospf-te-summary-00.txt>
Status of this Memo
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Abstract
Various Traffic Engineering extensions for OSPF have been proposed in
[KATZ, OSPFEXT] and others. However, these are basically applicable
only to intra-area Traffic Engineering since they do not support
inter-area advertisements of the resource information. This draft
proposes a new scheme for advertising the summarized resource
information for Traffic Engineering outside the area. It also
specifies a new LSA to achieve this advertisement.
1. Introduction
Advertising resource information in addition to topology information
using link state protocols is useful for achieving Traffic
Engineering in a network. Various Traffic Engineering extensions for
OSPF have been proposed in [KATZ, OSPFEXT] and others. For example,
[KATZ] proposes to extend OSPF using the Opaque LSA so as to
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advertise the parameters concerning Traffic Engineering. In these
proposals, however, the flooding scope of such an advertisement is
area-local, so the resource information is never advertised across
area border routers. In a hierarchical OSPF environment, therefore,
Traffic Engineering with Autonomous System (AS) scope is currently
impossible.
This draft proposes to advertise the summarized resource information
outside the area, which would allow Traffic Engineering with AS
scope. We specify the summarization schemes and the new LSA for the
advertisement.
2. Traffic Engineering Extensions to OSPF Summary LSA
2.1. Overview
We assume that resource information for Traffic Engineering is
advertised with an area-local scope by the Traffic Engineering LSA
(TE-LSA) proposed in [KATZ].
Using this information, the summarized resource information for each
destination network is computed and advertised in addition to the
OSPF Summary-LSA. One new LSA, the TE-Summary LSA, is defined for the
advertisement, which makes use of the Opaque LSA encoding [OPAQUE].
We address the summarization of the following resource information in
this draft. The support of other parameters is for further study.
Traffic Engineering Metric
The metric to the destination network used for Traffic
Engineering purposes.
Maximum Reservable Bandwidth
The maximum bandwidth that may be reserved on the path to the
corresponding destination network. This value may be greater than
the maximum bandwidth along the path, in which case the path may
be oversubscribed.
Unreserved Bandwidth
The amount of bandwidth that is not yet reserved on the path to
the corresponding destination network. The value is less than or
equal to the maximum reservable bandwidth.
Available Bandwidth
The amount of bandwidth that is not currently occupied by actual
traffic flows on the path to the corresponding destination
network. This value can be determined by monitoring the actual
amount of data traffic.
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This draft does not address resource class (or color). The resource
information included in the proposed TE-Summary LSA is aggregated in
a single class, whose value can be shared by multiple classes.
2.2. Summarization of Resource Information
The resource information for each destination network is summarized
at the area border routers and then is advertised throughout the
neighboring areas. Summarization schemes are different depending on
whether the destination network is located within the same area as
the area border router or not.
In the former case, the summarization of resource information is
performed based only on resource information from the TE-LSAs
advertised in the area.
If the destination network is not located within the same area as the
area border router, summarization requires resource information from
outside the area. The summarized resource information that is
advertised through the TE-Summary LSAs for the corresponding
destination network is taken into account together with the TE-LSAs.
This means that the area border router calculates the resource values
along the end-to-end available paths that go across area border
routers toward the destination network in the new TE-Summary LSA.
The methods of computing resource values included in the TE-Summary
LSAs may have to be standardized, but is left for further study.
2.3. Advertisement of TE-Summary LSA
The TE-Summary LSA is advertised together whenever a standard
Summary-LSA is advertised.
Furthermore, whenever an area border router calculates the summarized
bandwidth or metric based on the received resource information, it
compares the calculated value to the value that it advertised
previously. If the change exceeds the pre-determined threshold value
or ratio, a TE-Summary LSA with the updated information is re-
advertised.
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2.4. TE-Summary LSA Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS age | Options | 10 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque Type | Opaque ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS checksum | length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination IP Network Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Network Mask |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | TE Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Reservable Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unreserved Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Available Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Opaque Type
The type value is to be discussed.
Opaque ID
The arbitrary value used to maintain multiple TE-Summary LSAs is
included.
Destination IP Network Number
The same value as the Link State ID of the corresponding Summary-
LSA is included.
Network Mask
This indicates the destination network's IP address mask. The same
value as the Network Mask of the corresponding Summary-LSA is
included.
TE Metric
The TE metric is used for Traffic Engineering purposes. This metric
may be different than the standard Summary-LSA's TOS 0 metric.
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Maximum Reservable Bandwidth
The summarized maximum reservable bandwidth for the corresponding
destination is included. The bandwidth is encoded in IEEE single-
precision floating-point format.
Unreserved Bandwidth
The summarized unreserved bandwidth for the corresponding
destination is included. The bandwidth is encoded in IEEE single-
precision floating-point format.
Available Bandwidth
The summarized available bandwidth for the corresponding
destination is included. The bandwidth is encoded in IEEE single-
precision floating-point format.
4. Security Considerations
Security considerations are not addressed in this version of the
draft.
5. References
[OSPF] J. Moy, "OSPF Version 2", RFC2328, April 1998.
[OSPFEXT] G. Apostolopoulos, D. Williams, S. Kamat, R. Guerin, A.
Orda T. Przygienda, "QoS Routing Mechanisms and OSPF Extensions",
RFC2676, August 1999.
[KATZ] Dave Katz, Derek Yeung, "Traffic Engineering Extensions to
OSPF", <draft-katz-yeung-ospf-traffic-01.txt>, October 1999.
[OPAQUE] R. Coltun, "The OSPF Opaque LSA Option", RFC2370, July 1998.
6. Authors' Addresses
Norihito Fujita
NEC Corporation
C&C Media Research Laboratories
1-1, Miyazaki, 4-Chome, Miyamae-ku,
Kawasaki, Kanagawa, 216-8555, JAPAN
Phone: +81 (44) 856-2123
Fax: +81 (44) 856-2230
Email: n-fujita@ccm.cl.nec.co.jp
Atsushi Iwata
NEC Corporation
C&C Media Research Laboratories
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1-1, Miyazaki, 4-Chome, Miyamae-ku,
Kawasaki, Kanagawa, 216-8555, JAPAN
Phone: +81 (44) 856-2123
Fax: +81 (44) 856-2230
Email: iwata@ccm.cl.nec.co.jp
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