Internet DRAFT - draft-svshah-bgp-qos-sla-attribute
draft-svshah-bgp-qos-sla-attribute
Network Working Group S. Shah
Internet-Draft K. Patel
Intended status: Standards Track Cisco Systems
Expires: September 2, 2012 S. Bajaj
Juniper Networks
March 1, 2012
BGP attribute for QoS SLA advertisement
draft-svshah-bgp-qos-sla-attribute-00
Abstract
Out-of-band manual learning of SLA details and provisioning them in
general can be complex work for network administrators. For example,
Enterprise network administrators not only have to know what is their
SLA, for voice, video etc application traffic, with their Provider,
but they also require translating application groups to Classifier
groups as per provider's definition as well translate SLA to vendor
specific provisioning language. An in-band method of QoS signaling
can help to simplify some of the complexities. An optional
transitive BGP attribute proposed in this document intends to signal
SLA details in-band, across administrative boundaries (considered as
Autonomous Systems (AS)), and thus simplify/speed-up some of the
complex tasks.
Though the use-case with the proposed attribute is explicitly defined
in this document, purpose of this attribute is not limited to this
use-case only.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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 September 2, 2012.
Copyright Notice
Shah, et al. Expires September 2, 2012 [Page 1]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Shah, et al. Expires September 2, 2012 [Page 2]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. QoS Attribute Definition . . . . . . . . . . . . . . . . . . . 5
2.1. SLA_ADVERTISE sub-type Definition . . . . . . . . . . . . 5
3. Addition of QoS attribute in a BGP update message . . . . . . 11
3.1. SLA Contexts . . . . . . . . . . . . . . . . . . . . . . . 12
4. Processing of QoS attribute at forwarding nodes . . . . . . . 13
4.1. BGP node capable of processing QoS attribute . . . . . . . 13
4.2. BGP node not capable of processing QoS attribute . . . . . 13
5. Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1. Traffic class mapping . . . . . . . . . . . . . . . . . . 14
6. Deployment Consideration . . . . . . . . . . . . . . . . . . . 14
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
9. Security Considerations . . . . . . . . . . . . . . . . . . . 17
10. Normative References . . . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
Shah, et al. Expires September 2, 2012 [Page 3]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
1. Introduction
Definition of traffic classes and services for each traffic class
between 2 administrative boundaries, typically between Customer's
Edge (CE) and Provider's Edge (PE) or between one Provider's Edge to
another Provider's Edge, is contracted. The contract may exist in
different variations. The contract could be full line-rate or sub-
rate for aggregate traffic. Or it could be even with further finer
granular traffic distinction with services defined for standard code-
points or for specific set of pre-fix or for set of well-known
application types. Today, this contract is required to be learned
out-of-band. Learning SLAs out-of-band has associated costs with
provisioning them.
To over-come complexities associated with out-of-band learning of QoS
SLA, we are proposing a new BGP attribute to advertise/learn them in-
band [In rest of the document we may refer "QoS SLA" simply as
"SLA"]. BGP attribute proposed in this document is intended to
advertise SLA from one AS to a list of interested AS. QoS services
advertised could be for the incoming traffic to the AS community,
that is advertising SLA or could be for the outgoing traffic from the
advertiser or could be for both directions. Reception of and
reaction to advertised SLAs are optional for the receiver.
The aim with the signaling of this attribute, across administrative
boundaries, is to help network administrators speed up and simplify
QoS provisioning with automatic learning of SLAs and thus avoiding
complexities and possible errors with manual learning.
Requirements of QoS SLA advertisement and definition of its details
is generic and independent of BGP protocol. However, we find BGP a
suitable transport for reasons,
- There is no explicit protocol defined/available today for the
purpose of QoS SLA exchange
- The most common use-case of QoS SLA exchange is across Autonomous
Systems defined by BGP
- QoS attribute, apart for the use of SLA advertisement, in BGP can
be extended in the future for specific set of prefixes advertised
(flow or flow-group), thru BGP updates
We propose QoS as an optional transitive attribute, keeping SLA
advertisement as an internal of QoS attribute. This is to keep QoS
attribute open for extensions, in future, beyond SLA advertisement.
Shah, et al. Expires September 2, 2012 [Page 4]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
2. QoS Attribute Definition
The QoS Attribute proposed, in BGP, is an optional transitive
attribute (attribute type code to be assigned by IANA).
SLA_ADVERTISE is defined as one of the sub-types in the QoS attribute
value.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attr flag | QoS Attr type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
~ ~
| QoS Attr length/Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+..........................
Attribute flags
highest order bit (bit 0) -
MUST be set to 1, since this is an optional attribute
2nd higher order bit (bit 1) -
MUST be set to 1, since this is a transitive attribute
The first octet in the Value field of the QoS attribute is
Attribute specific flag
highest order bit (bit 0) -
It defines if update message MUST be dropped (if set to
1), when this is the last BGP receiver from the list of
AS this attribute is announced to, or MUST announce (if
set to 0) further to BGP peers
The purpose of this bit is discussed further in
subsequent sections.
Remaining bits are currently unused and MUST be set to 0
2.1. SLA_ADVERTISE sub-type Definition
The Value field for the QoS Attribute contains further TLVs, followed
to QoS Attribute flag described in previous section. One of the TLVs
we define, what is intended in this document, is tuple of (SLA
advertise sub-type, Length, Value)
Shah, et al. Expires September 2, 2012 [Page 5]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Attr flag | subType | sub type Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
| Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+..........................
subType - 8 bits
0x00 = reserved
0x01 = SLA_ADVERTISE_V1
0x02 - 0x0f = for future use
The format of SLA_ADVERTISE_V1 sub-type is,
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 32-bit source AS (Advertiser) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Optional advertiserid total len| Advertiser id TLVs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~
| |
~ ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 32-bit destination AS count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| variable list of destination AS |
~ .... ~
| .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|dir| Traffic Class count | Class Desc Len| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~
| |
~ Traffic Class Description ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Traffic Class Elements count/values ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Count| service type/value pair |
+-+-+-+-+-+-+-+-+ ~
| |
Shah, et al. Expires September 2, 2012 [Page 6]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
~ ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Repeat from Traffic Class Description for next Traffic Class ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Repeat from direction for SLA in the other direction ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Source AS
32-bit source AS number. This is the AS that is advertising SLA
0 = ignore Source and Destination AS list from this Value field.
Instead refer to Source and Destination AS as defined by BGP
message. QoS SLA sub-type specifics, from the QoS attribute,
MUST be removed by the receiver in such case.
Optional advertiser id total len
16-bit Source address identifier (optional).
0 = No optional identifier
Optional Advertiser id TLV
4-bit type
0x0 = reserved
0x1 = AF_IPV4, length = 32-bits, value = ipv4 prefix/address
0x2 = AF_IPV6, length = 128-bits, value = ipv6 prefix/address
0x3 = Path Identifier, length = 16-bits
0x4 to 0xf = for future use
Destination AS count
32-bit destination AS count to take variable length AS list.
This count has no functional value when Source AS is 0
0 = broadcast
Destination AS list
32-bit destination AS number, this field is omitted if broadcast
....
.... [as many as AS count]
....
Shah, et al. Expires September 2, 2012 [Page 7]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
Direction
02-bit for incoming or outgoing traffic,
0x0 = reserved
0x1 = incoming, from destination AS towards source AS
0x2 = outgoing, from source AS towards destination AS
0x3 = for future use
Traffic Class count (Classifier Groups count)
16-bit, count of number of classifier groups
00 = Advertisement to invalidate previous advertised SLA if was
advertised
Traffic Class Descr Length
08-bit, size of the length
0 = No description
Traffic Class Description
Ascii Description of the Traffic Class
Traffic Class Elements Count in a Traffic Class,
08-bit count of classifier elements in a specific Traffic Class
00 = this has relative definition. It means classify rest all
traffic that is not classified via earlier described
Traffic Classes.
It is RECOMMENDED to have 0 elements Traffic Class
definition last in the ordered list. If Advertised SLA does
not have this Traffic Class last in the advertised list,
receivers MUST re-order it, for the forwarding purpose, as
the last Traffic Class, in the ordered list, from the
source AS. It is MUST that advertisement from a specific
source does not have more than one Traffic classes with
element count 0. If there are more than one such Traffic
Classes then advertised SLA MUST be ignored. It is okay
for SLA message though to have none Traffic Class with
element count 0.
Classifier Element values in a Traffic Class (optional),
08-bit = type of the Element
variable-length = based on type of the Element
Shah, et al. Expires September 2, 2012 [Page 8]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
Element Types (08-bit)
0x00 = Invalid
0x01 = Reserved
0x02 = IP_DSCP, (length = 08-bits, value = 0..63)
0x03 = MPLS_EXP, (length = 03-bits, value = 0..7)
0x04 = 802_1Q_COS,(length = 03-bits, value = 0..7)
0x05 = 802_1Q_DEI,(length = 01-bit, value = 0..1)
0x06 to 0xff = for future use
Traffic Class Service count (for a Traffic Class under definition)
08-bit count of service attributes fields to follow with
type/value pair
List of service types and relevant values are discussed below
00 = no bounded service (also means Best Effort)
Traffic Class Service (optional),
16-bit = type of the field
variable-length = based on type of the service
- 0x00 = reserved
- 0x01 = MINRATE
32-bit, value in unit kbps
- 0x02 = MINRATE_BURST
32-bit, value in bytes
- 0x03 = MINRATE_IN_PROFILE_MARKING
04-bit, re-mark type
0x00 = Invalid
0x01 = Reserved
0x02 = IP_DSCP
0x03 = MPLS_EXP
0x04 = 802_1Q_COS
0x05 = 802_1Q_DEI
0x06 to 0x0f = for future use
08-bit, value
Shah, et al. Expires September 2, 2012 [Page 9]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
- 0x04 = MINRATE_OUT_PROFILE_MARKING
04-bit, re-mark type
0x00 = Invalid
0x01 = Reserved
0x02 = IP_DSCP
0x03 = MPLS_EXP
0x04 = 802_1Q_COS
0x05 = 802_1Q_DEI
0x06 to 0x0f = for future use
08-bit, value
- 0x05 = MAXRATE
32-bit, value in unit kbps
- 0x06 = MAXRATE_BURST
32-bit, value in bytes
- 0x07 = MAXRATE_IN_PROFILE_MARKING
04-bit, re-mark type
0x00 = Invalid
0x01 = Reserved
0x02 = IP_DSCP
0x03 = MPLS_EXP
0x04 = 802_1Q_COS
0x05 = 802_1Q_DEI
0x06 to 0x0f = for future use
08-bit, value
- 0x08 = MAXRATE_OUT_PROFILE_MARKING
04-bit, re-mark type
0x00 = Invalid
0x01 = DROP
0x02 = IP_DSCP
0x03 = MPLS_EXP
0x04 = 802_1Q_COS
0x05 = 802_1Q_DEI
0x06 to 0x0f = for future use
08-bit, value
In the case when MINRATE_IN_PROFILE_MARKING,
MINRATE_OUT_PROFILE_MARKING, MAXRATE_IN_PROFILE_MARKING and
MAXRATE_OUT_PROFILE_MARKING all of them are advertised,
- MINRATE_IN_PROFILE_MARKING takes highest precedence
(that is over MAXRATE_IN_PROFILE_MARKING)
Shah, et al. Expires September 2, 2012 [Page 10]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
- MAXRATE_IN_PROFILE_MARKING takes precedence over
MINRATE_OUT_PROFILE_MARKING
- and MAXRATE_OUT_PROFILE_MARKING takes precedence over
MINRATE_OUT_PROFILE_MARKING
- 0x09 = RELATIVE_PRIORITY
04-bit, priority value
lower the value, higher the priority
Relative priority indicates scheduling priority. For
example voice traffic, that requires lowest latency
compare to any other traffic, will have lowest value
advertised in relative priority. For two different
traffic classification groups where one application
group may be considered more important than the other
but from scheduling perspective do not require to be
distinguish with different priority. Relative priority
for those classification groups may be advertised with
the same value.
- 0x0A = SUB_TRAFFIC_CLASSES
variable-length, repeats all content described above from Traffic
Class count onwards.
For SLAs where a specific Traffic Class may further have
differentiated services for sub-group of Classifier Elements,
this service type SHOULD be used to further divide Traffic Class
in multiple sub-classes. Each sub-class then defined with their
own classifier elements and service types.
3. Addition of QoS attribute in a BGP update message
QoS attribute to advertise SLA MUST be added by the originator of a
BGP update message. Any BGP speaker in the forwarding path of a
message MUST NOT insert QoS attribute for the same prefix.
These messages in general SHOULD NOT be sent periodically just for
the purpose of keep alive. Since SLA changes are in-frequent, some
sort of SLA change policy can be considered as a trigger for
advertisement.
Shah, et al. Expires September 2, 2012 [Page 11]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
For cases where if earlier message has not yet reached to the
destination, a re-signaling is required. A new signaling sub-type
SLA_REQUEST is required for this purpose. Since BGP messages are
considered reliable, discussion of SLA_REQUEST, for this purpose or
any other purpose, is considered out of scope of this document.
BGP updates triggered as a result of QoS SLA change policy MUST set
QoS attribute flag to indicate receiver to not advertise BGP updates
further [Note that this flag is to indicate to drop the whole BGP
update message, not only QoS attribute]. Alternatively, if receiver
is next hop, sender MAY set NO_ADVERTISE community instead to
indicate receiver not to advertise BGP update message to other BGP
peers beyond next hop. Sender MUST set one of these fields when BGP
updates triggered are as a result of QoS SLA change policy. It is
RECOMMENDED to always set the QoS attribute flag, to indicate
receiver to drop BGP update message, when SLA sub-type message also
contains source AS. If source AS is set to 0 then it is RECOMMENDED
to use the community attribute NO_ADVERTISE.
Community NO_EXPORT MUST be set if QoS SLA not be advertised outside
a BGP confederation boundary.
For any SLA modification, originator MUST re-advertise entire SLA.
There is no provision to advertise partial SLA. To invalidate
previously advertised SLA, a message MUST be sent with new SLA
advertisement with Traffic Class count as 0.
3.1. SLA Contexts
In certain cases, advertisement may be to establish QoS SLA for point
to point connection between a specific destination and a specific
source. A point to point connection may be a physical link,
connecting BGP peers, or may be virtual link (eg. tunnel). A BGP
update message, in such cases, with source AS number and NLRI pre-fix
of source end-point can uniquely identify physical/virtual link
applicable to advertised SLA.
In the simplest case where PE and CE are directly connected via a
physical link and have only single link between them, CE can uniquely
identify forwarding link to PE with AS number of the PE and NLRI
prefix being an ip address of PE, to CE (that is next hop ip address
from CE to PE). SLA advertised thru BGP update message from PE to
CE, with PE's AS number and ip address, establishes SLA context for
the aggregate traffic through link CE to PE. SLA advertised thru BGP
update message from PE to CE, with PE's AS number and any other pre-
fix establishes SLA for that specific pre-fix under CE to PE link.
Shah, et al. Expires September 2, 2012 [Page 12]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
4. Processing of QoS attribute at forwarding nodes
4.1. BGP node capable of processing QoS attribute
If a BGP node is capable of processing QoS attribute, it optionally
MAY process the message. If advertised SLA has list of destination
AS, it MAY trim list and so count of destination AS to exclude ones
that are not required in further announcement of BGP updates.
BGP node MUST drop SLA related sub type from the QoS attribute, if
none of the AS from the destination list is in the forwarding path.
Rest of the QoS attributes message MAY be forwarded if there exist
other sub-types of QoS attribute and forwarding rules meets other
sub-types requirements. If there is no other sub-types existing in
the QoS attribute message then node MUST drop QoS attribute all
together. Rest other attributes and NLRI may be announced further if
it meets rules defined by other attributes and BGP protocol.
If BGP community, in the update message, is set to NO_ADVERTISE then
whole BGP update message MUST not be announced further irrespective
of any of the QoS attribute content.
If flag in the QoS attribute is set to not announce updates beyond
listed destinations then message MUST be dropped if there are no
destination left in the list to advertise to.
If SLA message is meant to be broadcast then message MUST not be
dropped/trimmed.
Except extracting entire SLA_ADVERTISE sub-type or trimming the list
of destination AS list (this is described more in Section 4), rest
all other content MUST not be modified by any intermediate receivers
of the message.
4.2. BGP node not capable of processing QoS attribute
If BGP node is not capable of processing QoS attribute, it MUST
forward attribute message as it is received.
5. Receiver
Reception of and reaction to advertised messages are optional for the
receiver.
Shah, et al. Expires September 2, 2012 [Page 13]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
As described in earlier section, while reacting to SLA advertisement
- receiver SHOULD invalidate previous advertised SLA and then if one
exists for advertised NLRI. If new advertised SLA update is with
non-zero Traffic Class count, new advertised SLA SHOULD be
installed. If new advertised SLA update is with Traffic Class
count 0, no action is required.
- If advertised QoS Attribute is with flag set to indicate to drop
this message, receiver MUST drop message if it is the last
receiver, in the update path, this message is advertised to.
If advertised SLA is for the next hop, in reverse path, the receiver
can establish advertised SLA for the whole link, the link could be
physical or virtual link, associated with the next hop. If NLRI
advertised in update message is not of the next hop, receiver may
establish advertised SLA for that specific prefix list under the
relevant link. It is completely up to the receiver to decide for
which prefix to accept advertised SLA and for which one to not.
5.1. Traffic class mapping
It is common where switching/routing method used in 2 different AS
could be different. For example, Provider may tunnel Customer's IP
traffic thru MPLS cloud. In such cases traffic class definition for
QoS services is also different in both AS. For the meaningful use of
advertised SLA in such cases, receiver is required to map traffic
class from one type to another.
In the example given, traffic classification in Customer AS could be
IP diffserv based whereas traffic classification in Provider AS could
be MPLS EXP based. Thus for advertised MPLS EXP based SLA from PE,
CE would require to map traffic class from IP diffserv based to MPLS
EXP type.
There are well-defined recommendations that exist for traffic class
mapping between two technologies. Receiver MAY use those defined
recommendations for traffic class mapping or MAY define its own as
per its network Traffic Class service definition to map to advertised
Traffic Classes. It is completely up to the receiver how to define
such traffic class mapping.
6. Deployment Consideration
Typical use-case aimed with this proposal is for Provider to
advertise contracted SLA to Customer Edge. SLA established between
customer and Provider is provisioned by the provider on the PE device
(facing Customer Edge). This provisioning, in a form supported by
Shah, et al. Expires September 2, 2012 [Page 14]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
Provider, is advertised thru proposed BGP QoS attribute to the
Customer Edge. Customer may read thru advertised SLA to provision
one on the Customer Edge link facing towards PE.
Contracted SLA from PE to CE may be full line-rate or sub-rate of a
link or finer granular controlled services. SLA is not required to
be advertised if the SLA contract is simply a physical link. SLA
advertise can be useful when contracted service is sub-rate of a link
and/or if for finer granular traffic classes that are controlled.
Like voice, video services may be capped to certain rate.
_______________
__________ / \
/ \ / \
/ \ / \
|CustomerSite|-----| Provider |
\ C/E P\E /
\__________/ \ /
\_______________/
AS 3 AS 2
SLA_ADVERTISE: AS2 to AS3
NLRI = PE ip address
Another use-case can be to advertise SLA among different network
sites within one Enterprise network. In Hub and Spoke deployments,
Hub may define SLA for individual spokes and advertise this SLA thru
BGP updates.
Shah, et al. Expires September 2, 2012 [Page 15]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
AS 2
_______________ ________
/ \ / \
__________ / \-----| Spoke2 |
/ \ / \ \________/
| Hub |-----| Provider | ________
\__________/ \ / / \
\ /-----| Spoke1 |
AS 3 \_______________/ \________/
AS 1
SLA_ADVERTISE: AS2 to AS3
NLRI = AS2 tunnel address
SLA_ADVERTISE: AS1 to AS3
NLRI = AS2 tunnel address
It very well could be possible that AS2 may first learn its SLA with
Provider from Provider Edge it is connected to and then advertises
same or subset of the SLA to AS3 with AS2 to AS3 tunnel's ip address
as NLRI.
Deployment options are not limited to involving CEs only. For any
contract between Provider to Provider, SLA may be advertised from one
PE to another PE also.
7. Acknowledgements
Thanks to Fred Baker for his suggestions and thanks to Ken Briley,
Rahul Patel and Fred Yip for the review.
8. IANA Considerations
This document defines a new BGP attribute. IANA maintains the list
of existing BGP attribute types. Proposal is to define a new
attribute type code for the QoS attribute.
With the proposal, there is a list defined for Traffic Class Elements
type and associated Service types. IANA will be required to maintain
list of both new types.
Shah, et al. Expires September 2, 2012 [Page 16]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
Proposed definition of Traffic Class Element Types
0x00 = Invalid
0x01 = Reserved
0x02 = IP_DSCP, (length = 08-bits, value = 0..63)
0x03 = MPLS_EXP, (length = 03-bits, value = 0..7)
0x04 = 802_1Q_COS,(length = 03-bits, value = 0..7)
0x05 = 802_1Q_DEI,(length = 01-bit, value = 0..1)
Proposed definition of Traffic Class Service Types
0x00 = reserved
0x01 = MINRATE
0x02 = MINRATE_BURST
0x03 = MINRATE_IN_PROFILE_MARKING
0x04 = MINRATE_OUT_PROFILE_MARKING
0x05 = MAXRATE
0x06 = MAXRATE_BURST
0x07 = MAXRATE_IN_PROFILE_MARKING
0x08 = MAXRATE_OUT_PROFILE_MARKING
0x09 = RELATIVE_PRIORITY
0x0A = SUB_TRAFFIC_CLASSES
9. Security Considerations
There is a potential for mis-behaved AS to advertise wrong SLA,
stealing identity of another AS. This resembles to problems already
identified and resolved, in the routing world, thru reverse path
forwarding check. One proposal, inline to RPF, to resolve such
threats is to have each BGP speaker node, in the forwarding path,
perform reverse path check on source AS.
Since we expect these messages to originate and distributed in the
managed network, there should not be any risks for identity theft.
Thus reverse path check is not considered in this proposal nor have
we considered any alternates. Such solutions can be explored later
if any such need.
10. Normative References
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
December 1998.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Shah, et al. Expires September 2, 2012 [Page 17]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, February 2006.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, December 1998.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
July 2003.
[RFC3140] Black, D., Brim, S., Carpenter, B., and F. Le Faucheur,
"Per Hop Behavior Identification Codes", RFC 3140,
June 2001.
Authors' Addresses
Shitanshu Shah
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
US
Email: svshah@cisco.com
Keyur Patel
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
US
Email: keyupate@cisco.com
Shah, et al. Expires September 2, 2012 [Page 18]
Internet-Draft BGP attribute for QoS SLA advertisement March 2012
Sandeep Bajaj
Juniper Networks
1194 N. Mathilda Avenue
Sunnyvale, CA 94089
US
Email: sbajaj@juniper.net
Shah, et al. Expires September 2, 2012 [Page 19]
