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Quick-Start Request
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... router along the path could,
in turn, either approve the requested rate, reduce the requested
rate, or indicate that the Quick-Start Request is not approved. (We
note that the `routers' referred to in this document also include the
...
... routers' referred to in this document also include the
IP-layer processing of the Quick-Start Request at the sender.) In
approving a Quick-Start Request ...
... Quick-Start Request at the sender.) In
approving a Quick-Start Request, a router does not give preferential
treatment to subsequent packets from that connection ...
... TCP packet.
If the Quick-Start Request is approved by all routers along the path,
then the TCP ...
... congestion control mechanisms of that connection. If the Quick-Start
Request is not approved, then the sender would use the default
congestion control ...
... * The path between the two endpoints is relatively stable, such that
the path used by the Quick-Start Request is generally the same path
used by the Quick-Start packets one round-trip time ...
... note that, while Quick-Start is incrementally deployable in this
sense, a Quick-Start Request cannot be approved for a particular
connection unless both end-nodes ...
...
* A router should only approve a Quick-Start Request if the output
link is underutilized. Any other approach will result in either
...
... IP, and routers along the path approving, modifying,
discarding, or ignoring (and therefore disallowing) the Quick-Start
Request. The receiver uses reliable, transport-level mechanisms to
...
... transport-level mechanisms to
inform the sender of the status of the Quick-Start Request. For
example, when TCP is used, the TCP ...
... TTL in the IP header)
of the Quick-Start Request packet, and returns this in the Quick-
Start Response. The sender ...
... Quick-Start TTL,
approving the Quick-Start Request.
If the request is approved by all the routers ...
... sender's IP
layer and both routers along the path approving the Quick-Start
Request, and the TCP receiver using the Quick-Start ...
... RTT. -->
Figure 1: A Successful Quick-Start Request.
Figure 2 shows an unsuccessful use of Quick-Start ...
... Quick-Start, with one of the
routers along the path not approving the Quick-Start Request. If the
Quick-Start Request is not approved, then the sender ...
... routers along the path not approving the Quick-Start Request. If the
Quick-Start Request is not approved, then the sender uses the default
congestion control ...
... V Use default initial cwnd. -->
Figure 2: An Unsuccessful Quick-Start Request.
...
...
The Quick-Start Request for IPv4 is defined as follows:
...
... Quick-Start Option for IPv4.
A Quick-Start Request.
The first byte contains the option field, which includes the one-bit ...
... random value.
Routers that approve the Quick-Start Request decrement the QS TTL
(mod 256) by the same amount that they decrement the IP TTL ...
...
Routers can approve the Quick-Start Request for a lower rate by
decreasing the Rate Request in the Quick-Start Request. Section 4.2
...
... Routers can approve the Quick-Start Request for a lower rate by
decreasing the Rate Request in the Quick-Start Request. Section 4.2
discusses the Quick-Start Response from the TCP ...
... Rate with the Rate Report field set to the approved rate, and the QS
Nonce set to the QS Nonce sent in the Quick-Start Request. The
packet containing the Report of Approved Rate MUST be either a
control packet sent before the first Quick-Start ...
... does not necessarily know if the control packet has been dropped in
the network. If the packet containing the Quick-Start Request is
acknowledged, but the acknowledgement packet does not contain a
Quick-Start ...
... set to zero.
We note that, unlike a Quick-Start Request sent at the beginning of a
connection, when a Quick-Start Request ...
... Quick-Start Request sent at the beginning of a
connection, when a Quick-Start Request is sent in the middle of a
connection, the connection ...
... header does not
have a checksum field, and modifying the Quick-Start Request in the
IPv6 Hop-by-Hop ...
... Processing the Quick-Start Request at Routers ...
... sending rate is zero. Each participating router can
either terminate or approve the Quick-Start Request. A router MUST
only approve a Quick-Start Request ...
... Quick-Start Request. A router MUST
only approve a Quick-Start Request if the output link is
underutilized, and if the router ...
... senders. Otherwise, the router reduces or terminates
the Quick-Start Request.
While the paragraph above defines the *semantics ...
... While the paragraph above defines the *semantics* of approving a
Quick-Start Request, this document does not specify the specific
algorithms to be used by routers ...
... algorithms to be used by routers in processing Quick-Start Requests
or Reports. This is similar to RFC 3168prop, which specifics the
...
...
A router that wishes to terminate the Quick-Start Request SHOULD
either delete the Quick-Start Request ...
... Quick-Start Request SHOULD
either delete the Quick-Start Request from the IP header or zero the
QS TTL ...
... QS TTL, QS Nonce, and Rate Request fields. Deleting the Quick-Start
Request saves resources because downstream routers will have no
...
... QS Nonce field to report back to the sender the
reason that the Quick-Start Request was denied, e.g., that the router
is denying all Quick-Start Requests ...
... Quick-Start Request was denied, e.g., that the router
is denying all Quick-Start Requests at this time, or that this
router, as a matter of policy, does not grant Quick-Start requests ...
... Quick-Start Requests at this time, or that this
router, as a matter of policy, does not grant Quick-Start requests.
A router that doesn't understand the Quick-Start Option ...
... router that doesn't understand the Quick-Start Option will simply
forward the packet with the Quick-Start Request unchanged (ensuring
that the TTL Diff will not match and Quick-Start ...
...
If the participating router has decided to approve the Quick-Start
Request, it does the following:
* The router ...
... * If the router is only willing to approve a Rate Request less than
that in the Quick-Start Request, then the router replaces the Rate
Request with a smaller value. The router ...
... Request with a smaller value. The router MUST NOT increase the
Rate Request in the Quick-Start Request. If the router decreases
...
...
If the router approves the Quick-Start Request, this approval SHOULD
be taken into account in the router's decision to accept or reject
...
... be taken into account in the router's decision to accept or reject
subsequent Quick-Start Requests (e.g., using a variable that tracks
the recent aggregate of accepted Quick-Start Requests). This
...
... subsequent Quick-Start Requests (e.g., using a variable that tracks
the recent aggregate of accepted Quick-Start Requests). This
consideration of earlier approved Quick-Start Requests is necessary
...
... the recent aggregate of accepted Quick-Start Requests). This
consideration of earlier approved Quick-Start Requests is necessary
to ensure that the router only approves a Quick-Start Request ...
... Quick-Start Requests is necessary
to ensure that the router only approves a Quick-Start Request when
the router judges that the output link ...
... router judges that the output link will remain underutilized if
this and earlier Quick-Start Requests are used by the senders.
...
... senders.
In addition, the approval of a Quick-Start Request SHOULD NOT be used
by the router to affect the treatment of the data packets ...
... round-trip times. That is, the
approval by the router of a Quick-Start Request does not give
differential treatment for Quick-Start data packets ...
...
A non-participating router forwards the Quick-Start Request
unchanged, without decrementing the QS TTL. The non-participating
...
... RFC1812]. As a result, the sender will be
able to detect that the Quick-Start Request had not been understood
or approved by all of the routers along the path.
...
... router that uses multipath routing for packets within a single
connection MUST NOT approve a Quick-Start Request. This is discussed
in more detail in Section 9.2.
...
... router may implement some policy for cheaters. For instance, the
router MAY decide to deny future Quick-Start Requests from this
sender, including, if desired, deleting Quick-Start Requests ...
... Quick-Start Requests from this
sender, including, if desired, deleting Quick-Start Requests from
future packets from this sender. Section 9.4.1 discusses misbehaving
...
... downstream routers have approved the
Quick-Start Request for a smaller rate or denied the use of Quick-
Start, and adjust its bandwidth ...
... IP header
of the TCP packet, called the Quick-Start Request packet. (We will
be somewhat loose in our use of "packet" vs. "segment" in this
...
... segment" in this
section.) When used for initial start-up, the Quick-Start Request
packet can be either the SYN or SYN ...
... TTL
Diff or the QS Nonce, then host A MUST assume that its Quick-Start
request failed. In this case, host A sends a Report of Approved Rate
with a Rate Report of zero, and uses TCP ...
... data packets are defined as
data packets sent as the result of a successful Quick-Start request,
up to the time when the first Quick-Start packet is acknowledged.
...
... Quick-Start. For example, host A could send a Quick-Start Request in
the SYN packet, and host ...
... Sending the Quick-Start Request ...
... Quick-Start Response is included, then the sender knows that
the Quick-Start Request has been denied, and can send a Report of
Approved Rate.
...
... could determine it was in a situation that would warrant transmitting
a Quick-Start Request.
As a general guideline, a TCP ...
... TCP receiver responds
to the receipt of a Quick-Start Request with a Quick-Start Response,
using the Quick-Start ...
... IP TTL and QS TTL fields in
the received Quick-Start Request packet, as calculated in equations
(1) or (2) (depending on whether IPv4 or IPv6 ...
... host B) that receives an IP packet containing a
Quick-Start Request passes the Quick-Start Request, along with the
value in the IP TTL ...
... IP packet containing a
Quick-Start Request passes the Quick-Start Request, along with the
value in the IP TTL field, to the receiving ...
... If the TCP host is willing to permit the Quick-Start Request, then a
Quick-Start Response option is included in the TCP header ...
... If an end host receives an IP packet with a Quick-Start Request with
a rate request of zero, then that host SHOULD NOT send a Quick-Start ...
... host (say, TCP host A) that sent a Quick-Start Request and
receives a Quick-Start Response in an acknowledgement first checks
...
... TTL Diff, and an equal
or lesser value for the Rate Request than that transmitted in the
Quick-Start Request. In addition, if the received Rate Request is K,
then the rightmost 2K bits of the QS Nonce ...
... bits in
the QS Nonce sent in the Quick-Start Request. If these checks are
not successful, then the Quick-Start Request failed, and the TCP ...
... QS Nonce sent in the Quick-Start Request. If these checks are
not successful, then the Quick-Start Request failed, and the TCP host
...
... match those bits in the QS Nonce sent in the Quick-Start Request, for
a received Rate Request of K, then the TCP host ...
... TCP host MUST NOT send
additional Quick-Start Requests during the life of the connection.
Whether or not the Quick-Start Request ...
... Quick-Start Requests during the life of the connection.
Whether or not the Quick-Start Request was successful, the host
receiving ...
... receiving the Quick-Start Response MUST send a Report of Approved
Rate. Similarly, if the packet containing the Quick-Start Request is
acknowledged, but the acknowledgement does not include a Quick-Start
...
... and the TCP host is going to use the Quick-Start Request, it MUST
start using it within one round-trip time ...
... Start Response, or within three seconds, whichever is smaller. To
use the Quick-Start Request, the host sets its Quick-Start congestion
window ...
... Quick-Start Option, or because of delays at the receiver in
responding to the Quick-Start Request packet. In this case, an
overly large round-trip-time estimate could have caused the TCP ...
... As an example, a TCP sender with an approved Quick-Start Request of R
KBps, B-byte packets including headers, and an RTT ...
... TCP sender was in slow-start prior to the Quick-Start Request,
and no packets were lost or marked since that time, then the sender
...
... traffic for pure ACK packets on the reverse path. For example, for
the largest Quick-Start Request of 1.3 Gbps, given a TCP sender with
...
... traffic on the reverse path.
One possibility, in cases with large Quick-Start Requests, would be
for TCP receivers ...
... for TCP receivers to send Quick-Start Requests to request bandwidth
for the acknowledgement traffic ...
... a measurement of the round-trip time, it can use the time between
the receipt of the Quick-Start Request and the Report of Approved
Rate.
...
... TCP, we have defined a "Quick-Start packet" as one of the packets
sent in the window immediately following a successful Quick-Start
Request. After detecting the loss or ECN-marking of a Quick-Start
...
... TCP MUST revert to the default congestion control procedures
that would have been used if the Quick-Start Request had not been
approved. For example, if Quick-Start is used for setting the
...
... ECN-marked, then the sender SHOULD
NOT make future Quick-Start Requests for this connection.
...
... TCP: A Quick-Start Request for a Larger Initial Window ...
... request a larger initial window: (1) interactions with Path MTU
Discovery (PMTUD); and (2) Quick-Start Request packets that are
discarded by middleboxes.
...
... A second possibility would be for the sender to delay sending the
Quick-Start Request for one round-trip time by sending the Quick-
Start ...
... Quick-Start Request Packets that are Discarded by Routers or ...
...
It is always possible for a TCP SYN packet carrying a Quick-Start
request to be dropped in the network due to congestion, or to be
...
... implementations set the initial RTO to one second. For a TCP SYN
packet sent with a Quick-Start request, the TCP sender SHOULD use an
...
... IP Quick-Start Option
for a Quick-Start Request, and it is also using bits in the TCP
header to negotiate ECN ...
... sender is not restricted
in the rate that it requests. As an example, a server might wait
and send a Quick-Start Request after a short interaction with the
client.
...
... client.
To use a Quick-Start Request in a connection that has already
experienced a congestion ...
... idle period.
A Quick-Start Request sent in the middle of a TCP connection
SHOULD be sent on a data packet ...
... (2) When to make a request:
A TCP connection MAY make a Quick-Start Request before the
connection has experienced a congestion ...
... congestion window that the sender would have used if the
Quick-Start request had not been approved, whichever is smaller.
...
...
* Routers along the forward path modify the Quick-Start Request as
appropriate.
...
... calculates the TTL Diff. If Host B approves the Quick-Start
Request, then Host B sends a Quick-Start Response in the TCP header ...
...
* Routers along the reverse path modify the Quick-Start Request as
appropriate.
...
... TTL, mod 256. Recall that the
sender considers the Quick-Start Request approved only if the value
of TTL Diff for the packet entering the network ...
... TCP sender incorrectly believes that the Quick-Start Request was
approved by all routers along the path. If the use of Quick-Start ...
... tunnel is
compatible with Quick-Start, with Quick-Start Requests being
rejected. Section 6.1 describes in more detail the ways that a
simple tunnel ...
... TCP sender incorrectly
believes that the Quick-Start Request was approved by all routers
along the path. This is discussed in Section 6.2 below.
...
... routers along the tunnel path to process
the Quick-Start Request and give feedback, resulting in the
appropriate possible acceptance of the Quick-Start Request. Some
...
... the Quick-Start Request and give feedback, resulting in the
appropriate possible acceptance of the Quick-Start Request. Some
tunnels that are compatible with Quick-Start ...
...
support Quick-Start, where all Quick-Start Requests along the path
will be rejected. The second approach is a Quick-Start-capable mode,
...
... Quick-Start but not support Quick-Start, resulting in
the rejection of all Quick-Start Requests that traverse the tunnel.
...
... encapsulation takes place. In this case, TTL Diff will
be changed, correctly causing the Quick-Start Request to be rejected.
For a simple tunnel, it is preferable if the Quick-Start Request ...
... Quick-Start Request to be rejected.
For a simple tunnel, it is preferable if the Quick-Start Request is
not copied to the outer header, saving the routers ...
... routers within the tunnel
from unnecessarily processing the Quick-Start Request. However, the
Quick-Start Request will be rejected correctly in this case whether
...
... from unnecessarily processing the Quick-Start Request. However, the
Quick-Start Request will be rejected correctly in this case whether
or not the Quick-Start Request is copied to the outer header ...
... Quick-Start Request will be rejected correctly in this case whether
or not the Quick-Start Request is copied to the outer header.
...
... Quick-Start. If
the outer header does not contain a Quick-Start Request, a Quick-
Start-aware tunnel ...
... Start-aware tunnel egress MUST reject the inner Quick-Start Request
by zeroing the Rate Request field in the inner header, or by deleting
...
... Quick-Start,
a valid Quick-Start Request with unchanged TTL Diff traverses in the
inner header ...
... header, while the outer header most likely does not carry a
Quick-Start Request. If the tunnel egress also does not support
Quick-Start ...
... tunnel egress also does not support
Quick-Start, it remains possible that the Quick-Start Request would
be falsely approved, because the packet is decapsulated using the
...
... be falsely approved, because the packet is decapsulated using the
Quick-Start Request from the inner header, and the value of TTL Diff
...
... QS TTL is not decremented, then the value of TTL Diff is changed, and
the Quick-Start Request will be denied. However, if the BITW
supports a host ...
... Quick-Start rate request field in the inner header to ensure that the
Quick-Start Request will be rejected if the tunnel egress does not
support Quick-Start ...
... tunnel ingress node does not choose to locally approve the
Quick-Start Request, then it MUST either delete the Quick-Start
option from the inner header ...
... TCP sender incorrectly believes
that the Quick-Start Request was approved by all routers along the
path.
...
... congestion control method of that protocol that
would have been used if the Quick-Start Request had not been
approved. In addition, the sender takes into account the
...
... SAF06] explores some of the
performance implications of overly large Quick-Start Requests, and
discusses heuristics that end-nodes ...
...
Quick-Start will be more effective if Quick-Start Requests are not
larger than necessary; every Quick-Start Request that is approved but
...
... Quick-Start will be more effective if Quick-Start Requests are not
larger than necessary; every Quick-Start Request that is approved but
not used (or not fully used) takes away from the bandwidth pool
...
... not used (or not fully used) takes away from the bandwidth pool
available for granting successive Quick-Start Requests.
...
... In this section, we briefly outline how a router might decide whether
or not to approve a Quick-Start Request. The router should ask the
following questions:
...
... Quick-Start bandwidth that could arrive due to recently approved
Quick-Start Requests. In this way, if an underutilized router
experiences a flood ...
... router
experiences a flood of Quick-Start Requests, the router can begin to
deny Quick-Start Requests ...
... Quick-Start Requests, the router can begin to
deny Quick-Start Requests while the output link is still
underutilized.
...
... router's output link has been underutilized and the
aggregate of the Quick-Start Request Rate options granted is low
enough to prevent a near-term bandwidth shortage, then the router ...
... bandwidth shortage, then the router
could approve the Quick-Start Request.
Section 10.2 discusses some of the implementation issues in
...
...
Section 10.2 discusses some of the implementation issues in
processing Quick-Start Requests at routers. [SAF06] discusses the
...
... algorithms at the router for deciding
whether to approve a Quick-Start Request. In order to explore the
limits of the possible functionality at routers, [SAF06 ...
... routers along the path.
The cost of having a Quick-Start Request packet dropped:
Measurement studies cited earlier [MAF04] suggest that on a wide
range ...
... sender one risk in using
Quick-Start is that the packet carrying the Quick-Start Request could
be dropped in the network. It is particularly costly to the sender ...
... data packets. This should be an unlikely situation
because routers are expected to approve Quick-Start Requests only
when they are significantly underutilized. However, a transient
increase in cross-traffic ...
... queue could result in packet losses even when the Quick-Start Request
was approved by all of the routers along the path. If a Quick-Start ...
... sender reverts to the congestion control
mechanisms it would have used if the Quick-Start Request had not been
approved, so the performance cost to the connection ...
... bandwidth on the output
link over the last several seconds, processing the Quick-Start
request, and keeping a counter of the aggregate Quick-Start rate
...
... Another drawback of Quick-Start is that packets containing the
Quick-Start Request message might not take the fast path in routers,
particularly in the beginning of Quick-Start ...
... Sections 4.1 and 4.7, not all packets would carry the Quick-Start
option. In addition, for the underutilized links where Quick-Start
Requests could actually be approved, or in typical environments where
most of the packets belong to large flows, the burden of the Quick-
...
... routers would be considerably reduced. Nevertheless,
it is still conceivable, in the worst case, that many packets would
carry Quick-Start Requests; this could slow down the processing of
Quick-Start packets in routers ...
... 9.6, routers can easily protect against this by enforcing a limit on
the rate at which Quick-Start Requests will be considered. [RW03]
and [RW04 ...
... Quick-Start is that it presumes that the data
packets of a connection will follow the same path as the Quick-Start
request packet. If this is not the case, then the connection could
be sending the Quick-Start ...
... performance
when there is a routing change immediately after the Quick-Start
Request is approved, and the Quick-Start data packets follow a
...
... Quick-Start data packets follow a
different path from that of the original Quick-Start Request. This
is, however, similar to what would happen for a connection with
...
... routing for
packets within a single connection must not approve a Quick-Start
Request. Quick-Start would not perform robustly in an environment
with multipath routing ...
... connection
routinely follow different paths. In such an environment, the
Quick-Start Request and some fraction of the packets in the
connection might take an underutilized path, while the rest of the
...
... non-IP queue or
bottleneck would be configured to reject Quick-Start Requests if that
was appropriate. One would hope that, in general, IP networks are
...
... routers could take the traffic class into account when deciding
whether or not to grant the Quick-Start Request. We don't address
this context ...
... Routers are also free to take into account their own priority
classifications in processing Quick-Start Requests.
...
... transport sender could try to transmit data at a higher rate than
that approved in the Quick-Start Request. The network could use a
traffic ...
... does not exceed the Rate Request actually approved at that point in
the network in the previous Quick-Start Request from that connection.
The required Approved Rate report also allows traffic ...
... router or receiver receives an Approved Rate report that is
larger than the Rate Request in the Quick-Start Request approved for
that sender for that connection ...
...
that sender, e.g., by deleting the Quick-Start Request from future
packets from that sender. We note that routers ...
... If a router sees a Report of Approved Rate, and did not see an
earlier Quick-Start Request, then either the sender could be
cheating, or the connection ...
... cheating, or the connection's path could have changed since the
Quick-Start Request was sent. In either case, the router could
decide to deny future Quick-Start Requests ...
... Quick-Start Request was sent. In either case, the router could
decide to deny future Quick-Start Requests for this connection. In
particular, it is reasonable for the router ...
... connection. In
particular, it is reasonable for the router to deny a Quick-Start
request if either the sender is cheating, or if the connection path
...
...
If a router approved a Quick-Start Request, but does not see a
subsequent Approved Rate report, then there are several
possibilities: (1) the request was denied and/or dropped downstream ...
... network; or (4) the Approved Rate report took a different path from
the Quick-Start Request. In any of these cases, the router would be
justified in denying future Quick-Start Requests ...
... Quick-Start Request. In any of these cases, the router would be
justified in denying future Quick-Start Requests for this connection.
...
... In any of the cases mentioned in the three paragraphs above (i.e., an
Approved Rate report that is larger than the Rate Request in the
earlier Quick-Start Request, a Report of Approved Rate with no
preceding Rate Request, or a Rate Request with no Report of Approved
Rate), a traffic ...
... What are the incentives for a sender to cheat by over-sending after a
Quick-Start Request? Assuming that the sender's interests are
measured by a performance ...
... interests to cheat. The incentives for a sender to cheat by over-
sending after a Quick-Start Request are not that different from the
incentives for a sender to cheat by over-sending even in the absence
...
... receiver to lie to the
sender about whether the Quick-Start Request was approved, by falsely
reporting the TTL Diff and QS Nonce ...
... QS Nonce. If a router that understands
the Quick-Start Request denies the request by deleting the request or
by zeroing the QS TTL and QS Nonce ...
... QS
nonce for a reported rate request of K is 1/(2K).
However, if the Quick-Start Request is denied only by a non-Quick-
Start-capable router ...
... QS Nonce fields, then the receiver could lie about whether
the Quick-Start Requests were approved by modifying the QS TTL in
successive requests received from the same host ...
... host. In particular, if
the sender does not act on a Quick-Start Request, then the receiver
could decrement the QS TTL ...
... by two in the following received request, until the sender acts on
one of the Quick-Start Requests.
Unfortunately, if a router ...
... What would be the incentives for a receiver to cheat in reporting on
a Quick-Start Request, in the absence of a mechanism such as the QS
Nonce? In some cases, cheating would be of clear benefit to the
receiver ...
... receiver to
lie to the sender about the Rate Request for an approved Quick-Start
Request, by increasing the value of the Rate Request field. However,
the receiver doesn't necessarily know the Rate Request in the
...
... the receiver doesn't necessarily know the Rate Request in the
original Quick-Start Request sent by the sender, and a higher Rate
Request reported by the receiver ...
... by the sender. For example, if the sender sends a Quick-Start
Request with a Rate Request of X, and the receiver reports receiving
...
... receiver reports receiving
a Quick-Start Request with a Rate Request of Y > X, then the sender
knows that either some router ...
...
If the sender sends a Quick-Start Request with a Rate Request of Z,
the receiver receives the Quick-Start Request ...
... Quick-Start Request with a Rate Request of Z,
the receiver receives the Quick-Start Request with an approved Rate
Request of X, and reports a Rate Request of Y, for X < Y <= Z, then
the receiver ...
... additional protection would be for a router that decreases a Rate
Request in a Quick-Start Request to report the decrease directly to
the sender. However, this could lead to many reports back to the
...
... cooperating ingress and egress routers to collude to falsely modify
the Quick-Start Request so that it appears to have been approved by
all the routers along the path. With ECN ...
... Quick-Start, the collusion of the ingress and
egress routers to make it falsely appear that a Quick-Start Request
was approved sometimes would give an advantage to the traffic covered
...
... router along the path really
does not have enough available bandwidth to approve the Quick-Start
Request, then Quick-Start packets sent as a result of the falsely
approved request could be dropped in the network ...
... routers could collude to prevent intermediate routers from denying a
Quick-Start Request, it would not always be to the connection's
advantage for this to happen. One defense ...
... connections that seem to be using Quick-Start after a Quick-Start
Request was denied, or that are reporting an Approved Rate higher
than that actually approved by that router.
...
... ECN-capability as well as about
Quick-Start, then the result could be that the Quick-Start Request
falsely appears to the sender to have been approved, and the Quick-
...
... Start Request was approved) as well as false negatives (with the
sender incorrectly believing that the Quick-Start Request was
denied).
...
... state
load and (2) attacks with bogus Quick-Start Requests to temporarily
tie up available Quick-Start bandwidth ...
... bandwidth, preventing routers from
approving Quick-Start Requests from other connections. Routers can
...
... protect against the first kind of attack by applying a simple limit
on the rate at which Quick-Start Requests will be considered by the
router.
...
... bandwidth, is more difficult to defend against. As discussed in
[SAF06], Quick-Start Requests that are not going to be used, either
because they are from malicious attackers or because they are denied
...
... bandwidth, resulting in routers denying
subsequent Quick-Start Requests that, if approved, would in fact have
been used.
...
... Implementation Issues for Sending Quick-Start Requests ...
... save the QS Nonce and the TTL Diff when the Quick-Start Request is
sent, and to implement an additional timer for the paced transmission
...
... Implementation Issues for Processing Quick-Start Requests ...
... host gets updates of the changing bandwidth. It seems
appropriate that Quick-Start Requests would be handled particularly
conservatively for links with variable bandwidth ...
... links with variable bandwidth; to avoid cases
where Quick-Start Requests are approved, the link bandwidth is
reduced, and the data packets ...
... multi-access links should be
particularly conservative in granting Quick-Start Requests. In
particular, for some multi-access links ...
... and state load from an attack of Quick-Start Requests. Section 9.6
also discusses a potential attack on the available Quick-Start ...
... Quick-Start
bandwidth by sending bogus Quick-Start Requests for bandwidth that
will not, in fact, be used. While this impacts the global usability
...
... tunnels that are not compatible with
Quick-Start. In this case, it is possible that a Quick-Start Request
is erroneously considered approved by the sender without the routers ...
...
This document has proposed using an IP Option for the Quick-Start
Request from the sender to the receiver, and using transport
mechanisms ...
... Quick-Start Request. The ICMP Quick-Start Request would have to pass
by the routers on the path to the receiver ...
... router
along the path. A router that does not approve the Quick-Start
Request, even with a decreased value for the Requested Rate, would
delete the ICMP ...
... of feedback from the receiver. If the ICMP Quick-Start Request was
dropped in the network due to congestion ...
... processing at routers. A greater advantage is that if middleboxes
were blocking packets with Quick-Start Requests, using the Quick-
Start Request in a separate ICMP packet ...
... Quick-Start Option,
one would have to have a TCP-level Quick-Start Request packet that
could be sent concurrently with, but separately from, the TCP SYN
packet.)
...
... firewalls and middleboxes may not forward the ICMP Quick-Start
Request packets. (If an ICMP Reply packet from a router to the
...
... RSVP [RFC2205] could be used as a bearer
protocol for carrying the Quick-Start Requests. Because routers are
expected to process RSVP ...
... Quick-Start capable
routers along the path would inspect the Quick-Start Request object
in the RSVP Path message ...
... RSVP router did not understand the
Quick-Start Request object, it would reject the entire RSVP message
and send an RSVP ...
... PathErr message back to the sender. When an RSVP
message with the Quick-Start Request object reaches the receiver, the
...
... of IP options earlier. If the RSVP message with the Quick-Start
Request object was dropped along the path, the transport sender would
...
... discussion about benefits and drawbacks of using ICMP for
making the Quick-Start Request also applies to the RSVP case. If the
Quick-Start Request ...
... Quick-Start Request also applies to the RSVP case. If the
Quick-Start Request was transmitted in a separate packet instead of
as an IP option, the transport p