![Neal Cardwell](/assets/img/avatar_default.png)
This commit implements a new TCP congestion control algorithm: BBR (Bottleneck Bandwidth and RTT). A detailed description of BBR will be published in ACM Queue, Vol. 14 No. 5, September-October 2016, as "BBR: Congestion-Based Congestion Control". BBR has significantly increased throughput and reduced latency for connections on Google's internal backbone networks and google.com and YouTube Web servers. BBR requires only changes on the sender side, not in the network or the receiver side. Thus it can be incrementally deployed on today's Internet, or in datacenters. The Internet has predominantly used loss-based congestion control (largely Reno or CUBIC) since the 1980s, relying on packet loss as the signal to slow down. While this worked well for many years, loss-based congestion control is unfortunately out-dated in today's networks. On today's Internet, loss-based congestion control causes the infamous bufferbloat problem, often causing seconds of needless queuing delay, since it fills the bloated buffers in many last-mile links. On today's high-speed long-haul links using commodity switches with shallow buffers, loss-based congestion control has abysmal throughput because it over-reacts to losses caused by transient traffic bursts. In 1981 Kleinrock and Gale showed that the optimal operating point for a network maximizes delivered bandwidth while minimizing delay and loss, not only for single connections but for the network as a whole. Finding that optimal operating point has been elusive, since any single network measurement is ambiguous: network measurements are the result of both bandwidth and propagation delay, and those two cannot be measured simultaneously. While it is impossible to disambiguate any single bandwidth or RTT measurement, a connection's behavior over time tells a clearer story. BBR uses a measurement strategy designed to resolve this ambiguity. It combines these measurements with a robust servo loop using recent control systems advances to implement a distributed congestion control algorithm that reacts to actual congestion, not packet loss or transient queue delay, and is designed to converge with high probability to a point near the optimal operating point. In a nutshell, BBR creates an explicit model of the network pipe by sequentially probing the bottleneck bandwidth and RTT. On the arrival of each ACK, BBR derives the current delivery rate of the last round trip, and feeds it through a windowed max-filter to estimate the bottleneck bandwidth. Conversely it uses a windowed min-filter to estimate the round trip propagation delay. The max-filtered bandwidth and min-filtered RTT estimates form BBR's model of the network pipe. Using its model, BBR sets control parameters to govern sending behavior. The primary control is the pacing rate: BBR applies a gain multiplier to transmit faster or slower than the observed bottleneck bandwidth. The conventional congestion window (cwnd) is now the secondary control; the cwnd is set to a small multiple of the estimated BDP (bandwidth-delay product) in order to allow full utilization and bandwidth probing while bounding the potential amount of queue at the bottleneck. When a BBR connection starts, it enters STARTUP mode and applies a high gain to perform an exponential search to quickly probe the bottleneck bandwidth (doubling its sending rate each round trip, like slow start). However, instead of continuing until it fills up the buffer (i.e. a loss), or until delay or ACK spacing reaches some threshold (like Hystart), it uses its model of the pipe to estimate when that pipe is full: it estimates the pipe is full when it notices the estimated bandwidth has stopped growing. At that point it exits STARTUP and enters DRAIN mode, where it reduces its pacing rate to drain the queue it estimates it has created. Then BBR enters steady state. In steady state, PROBE_BW mode cycles between first pacing faster to probe for more bandwidth, then pacing slower to drain any queue that created if no more bandwidth was available, and then cruising at the estimated bandwidth to utilize the pipe without creating excess queue. Occasionally, on an as-needed basis, it sends significantly slower to probe for RTT (PROBE_RTT mode). BBR has been fully deployed on Google's wide-area backbone networks and we're experimenting with BBR on Google.com and YouTube on a global scale. Replacing CUBIC with BBR has resulted in significant improvements in network latency and application (RPC, browser, and video) metrics. For more details please refer to our upcoming ACM Queue publication. Example performance results, to illustrate the difference between BBR and CUBIC: Resilience to random loss (e.g. from shallow buffers): Consider a netperf TCP_STREAM test lasting 30 secs on an emulated path with a 10Gbps bottleneck, 100ms RTT, and 1% packet loss rate. CUBIC gets 3.27 Mbps, and BBR gets 9150 Mbps (2798x higher). Low latency with the bloated buffers common in today's last-mile links: Consider a netperf TCP_STREAM test lasting 120 secs on an emulated path with a 10Mbps bottleneck, 40ms RTT, and 1000-packet bottleneck buffer. Both fully utilize the bottleneck bandwidth, but BBR achieves this with a median RTT 25x lower (43 ms instead of 1.09 secs). Our long-term goal is to improve the congestion control algorithms used on the Internet. We are hopeful that BBR can help advance the efforts toward this goal, and motivate the community to do further research. Test results, performance evaluations, feedback, and BBR-related discussions are very welcome in the public e-mail list for BBR: https://groups.google.com/forum/#!forum/bbr-dev NOTE: BBR *must* be used with the fq qdisc ("man tc-fq") with pacing enabled, since pacing is integral to the BBR design and implementation. BBR without pacing would not function properly, and may incur unnecessary high packet loss rates. Signed-off-by: Van Jacobson <vanj@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Nandita Dukkipati <nanditad@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
730 lines
25 KiB
Plaintext
730 lines
25 KiB
Plaintext
#
|
|
# IP configuration
|
|
#
|
|
config IP_MULTICAST
|
|
bool "IP: multicasting"
|
|
help
|
|
This is code for addressing several networked computers at once,
|
|
enlarging your kernel by about 2 KB. You need multicasting if you
|
|
intend to participate in the MBONE, a high bandwidth network on top
|
|
of the Internet which carries audio and video broadcasts. More
|
|
information about the MBONE is on the WWW at
|
|
<http://www.savetz.com/mbone/>. For most people, it's safe to say N.
|
|
|
|
config IP_ADVANCED_ROUTER
|
|
bool "IP: advanced router"
|
|
---help---
|
|
If you intend to run your Linux box mostly as a router, i.e. as a
|
|
computer that forwards and redistributes network packets, say Y; you
|
|
will then be presented with several options that allow more precise
|
|
control about the routing process.
|
|
|
|
The answer to this question won't directly affect the kernel:
|
|
answering N will just cause the configurator to skip all the
|
|
questions about advanced routing.
|
|
|
|
Note that your box can only act as a router if you enable IP
|
|
forwarding in your kernel; you can do that by saying Y to "/proc
|
|
file system support" and "Sysctl support" below and executing the
|
|
line
|
|
|
|
echo "1" > /proc/sys/net/ipv4/ip_forward
|
|
|
|
at boot time after the /proc file system has been mounted.
|
|
|
|
If you turn on IP forwarding, you should consider the rp_filter, which
|
|
automatically rejects incoming packets if the routing table entry
|
|
for their source address doesn't match the network interface they're
|
|
arriving on. This has security advantages because it prevents the
|
|
so-called IP spoofing, however it can pose problems if you use
|
|
asymmetric routing (packets from you to a host take a different path
|
|
than packets from that host to you) or if you operate a non-routing
|
|
host which has several IP addresses on different interfaces. To turn
|
|
rp_filter on use:
|
|
|
|
echo 1 > /proc/sys/net/ipv4/conf/<device>/rp_filter
|
|
or
|
|
echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter
|
|
|
|
Note that some distributions enable it in startup scripts.
|
|
For details about rp_filter strict and loose mode read
|
|
<file:Documentation/networking/ip-sysctl.txt>.
|
|
|
|
If unsure, say N here.
|
|
|
|
config IP_FIB_TRIE_STATS
|
|
bool "FIB TRIE statistics"
|
|
depends on IP_ADVANCED_ROUTER
|
|
---help---
|
|
Keep track of statistics on structure of FIB TRIE table.
|
|
Useful for testing and measuring TRIE performance.
|
|
|
|
config IP_MULTIPLE_TABLES
|
|
bool "IP: policy routing"
|
|
depends on IP_ADVANCED_ROUTER
|
|
select FIB_RULES
|
|
---help---
|
|
Normally, a router decides what to do with a received packet based
|
|
solely on the packet's final destination address. If you say Y here,
|
|
the Linux router will also be able to take the packet's source
|
|
address into account. Furthermore, the TOS (Type-Of-Service) field
|
|
of the packet can be used for routing decisions as well.
|
|
|
|
If you are interested in this, please see the preliminary
|
|
documentation at <http://www.compendium.com.ar/policy-routing.txt>
|
|
and <ftp://post.tepkom.ru/pub/vol2/Linux/docs/advanced-routing.tex>.
|
|
You will need supporting software from
|
|
<ftp://ftp.tux.org/pub/net/ip-routing/>.
|
|
|
|
If unsure, say N.
|
|
|
|
config IP_ROUTE_MULTIPATH
|
|
bool "IP: equal cost multipath"
|
|
depends on IP_ADVANCED_ROUTER
|
|
help
|
|
Normally, the routing tables specify a single action to be taken in
|
|
a deterministic manner for a given packet. If you say Y here
|
|
however, it becomes possible to attach several actions to a packet
|
|
pattern, in effect specifying several alternative paths to travel
|
|
for those packets. The router considers all these paths to be of
|
|
equal "cost" and chooses one of them in a non-deterministic fashion
|
|
if a matching packet arrives.
|
|
|
|
config IP_ROUTE_VERBOSE
|
|
bool "IP: verbose route monitoring"
|
|
depends on IP_ADVANCED_ROUTER
|
|
help
|
|
If you say Y here, which is recommended, then the kernel will print
|
|
verbose messages regarding the routing, for example warnings about
|
|
received packets which look strange and could be evidence of an
|
|
attack or a misconfigured system somewhere. The information is
|
|
handled by the klogd daemon which is responsible for kernel messages
|
|
("man klogd").
|
|
|
|
config IP_ROUTE_CLASSID
|
|
bool
|
|
|
|
config IP_PNP
|
|
bool "IP: kernel level autoconfiguration"
|
|
help
|
|
This enables automatic configuration of IP addresses of devices and
|
|
of the routing table during kernel boot, based on either information
|
|
supplied on the kernel command line or by BOOTP or RARP protocols.
|
|
You need to say Y only for diskless machines requiring network
|
|
access to boot (in which case you want to say Y to "Root file system
|
|
on NFS" as well), because all other machines configure the network
|
|
in their startup scripts.
|
|
|
|
config IP_PNP_DHCP
|
|
bool "IP: DHCP support"
|
|
depends on IP_PNP
|
|
---help---
|
|
If you want your Linux box to mount its whole root file system (the
|
|
one containing the directory /) from some other computer over the
|
|
net via NFS and you want the IP address of your computer to be
|
|
discovered automatically at boot time using the DHCP protocol (a
|
|
special protocol designed for doing this job), say Y here. In case
|
|
the boot ROM of your network card was designed for booting Linux and
|
|
does DHCP itself, providing all necessary information on the kernel
|
|
command line, you can say N here.
|
|
|
|
If unsure, say Y. Note that if you want to use DHCP, a DHCP server
|
|
must be operating on your network. Read
|
|
<file:Documentation/filesystems/nfs/nfsroot.txt> for details.
|
|
|
|
config IP_PNP_BOOTP
|
|
bool "IP: BOOTP support"
|
|
depends on IP_PNP
|
|
---help---
|
|
If you want your Linux box to mount its whole root file system (the
|
|
one containing the directory /) from some other computer over the
|
|
net via NFS and you want the IP address of your computer to be
|
|
discovered automatically at boot time using the BOOTP protocol (a
|
|
special protocol designed for doing this job), say Y here. In case
|
|
the boot ROM of your network card was designed for booting Linux and
|
|
does BOOTP itself, providing all necessary information on the kernel
|
|
command line, you can say N here. If unsure, say Y. Note that if you
|
|
want to use BOOTP, a BOOTP server must be operating on your network.
|
|
Read <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
|
|
|
|
config IP_PNP_RARP
|
|
bool "IP: RARP support"
|
|
depends on IP_PNP
|
|
help
|
|
If you want your Linux box to mount its whole root file system (the
|
|
one containing the directory /) from some other computer over the
|
|
net via NFS and you want the IP address of your computer to be
|
|
discovered automatically at boot time using the RARP protocol (an
|
|
older protocol which is being obsoleted by BOOTP and DHCP), say Y
|
|
here. Note that if you want to use RARP, a RARP server must be
|
|
operating on your network. Read
|
|
<file:Documentation/filesystems/nfs/nfsroot.txt> for details.
|
|
|
|
config NET_IPIP
|
|
tristate "IP: tunneling"
|
|
select INET_TUNNEL
|
|
select NET_IP_TUNNEL
|
|
---help---
|
|
Tunneling means encapsulating data of one protocol type within
|
|
another protocol and sending it over a channel that understands the
|
|
encapsulating protocol. This particular tunneling driver implements
|
|
encapsulation of IP within IP, which sounds kind of pointless, but
|
|
can be useful if you want to make your (or some other) machine
|
|
appear on a different network than it physically is, or to use
|
|
mobile-IP facilities (allowing laptops to seamlessly move between
|
|
networks without changing their IP addresses).
|
|
|
|
Saying Y to this option will produce two modules ( = code which can
|
|
be inserted in and removed from the running kernel whenever you
|
|
want). Most people won't need this and can say N.
|
|
|
|
config NET_IPGRE_DEMUX
|
|
tristate "IP: GRE demultiplexer"
|
|
help
|
|
This is helper module to demultiplex GRE packets on GRE version field criteria.
|
|
Required by ip_gre and pptp modules.
|
|
|
|
config NET_IP_TUNNEL
|
|
tristate
|
|
select DST_CACHE
|
|
default n
|
|
|
|
config NET_IPGRE
|
|
tristate "IP: GRE tunnels over IP"
|
|
depends on (IPV6 || IPV6=n) && NET_IPGRE_DEMUX
|
|
select NET_IP_TUNNEL
|
|
help
|
|
Tunneling means encapsulating data of one protocol type within
|
|
another protocol and sending it over a channel that understands the
|
|
encapsulating protocol. This particular tunneling driver implements
|
|
GRE (Generic Routing Encapsulation) and at this time allows
|
|
encapsulating of IPv4 or IPv6 over existing IPv4 infrastructure.
|
|
This driver is useful if the other endpoint is a Cisco router: Cisco
|
|
likes GRE much better than the other Linux tunneling driver ("IP
|
|
tunneling" above). In addition, GRE allows multicast redistribution
|
|
through the tunnel.
|
|
|
|
config NET_IPGRE_BROADCAST
|
|
bool "IP: broadcast GRE over IP"
|
|
depends on IP_MULTICAST && NET_IPGRE
|
|
help
|
|
One application of GRE/IP is to construct a broadcast WAN (Wide Area
|
|
Network), which looks like a normal Ethernet LAN (Local Area
|
|
Network), but can be distributed all over the Internet. If you want
|
|
to do that, say Y here and to "IP multicast routing" below.
|
|
|
|
config IP_MROUTE
|
|
bool "IP: multicast routing"
|
|
depends on IP_MULTICAST
|
|
help
|
|
This is used if you want your machine to act as a router for IP
|
|
packets that have several destination addresses. It is needed on the
|
|
MBONE, a high bandwidth network on top of the Internet which carries
|
|
audio and video broadcasts. In order to do that, you would most
|
|
likely run the program mrouted. If you haven't heard about it, you
|
|
don't need it.
|
|
|
|
config IP_MROUTE_MULTIPLE_TABLES
|
|
bool "IP: multicast policy routing"
|
|
depends on IP_MROUTE && IP_ADVANCED_ROUTER
|
|
select FIB_RULES
|
|
help
|
|
Normally, a multicast router runs a userspace daemon and decides
|
|
what to do with a multicast packet based on the source and
|
|
destination addresses. If you say Y here, the multicast router
|
|
will also be able to take interfaces and packet marks into
|
|
account and run multiple instances of userspace daemons
|
|
simultaneously, each one handling a single table.
|
|
|
|
If unsure, say N.
|
|
|
|
config IP_PIMSM_V1
|
|
bool "IP: PIM-SM version 1 support"
|
|
depends on IP_MROUTE
|
|
help
|
|
Kernel side support for Sparse Mode PIM (Protocol Independent
|
|
Multicast) version 1. This multicast routing protocol is used widely
|
|
because Cisco supports it. You need special software to use it
|
|
(pimd-v1). Please see <http://netweb.usc.edu/pim/> for more
|
|
information about PIM.
|
|
|
|
Say Y if you want to use PIM-SM v1. Note that you can say N here if
|
|
you just want to use Dense Mode PIM.
|
|
|
|
config IP_PIMSM_V2
|
|
bool "IP: PIM-SM version 2 support"
|
|
depends on IP_MROUTE
|
|
help
|
|
Kernel side support for Sparse Mode PIM version 2. In order to use
|
|
this, you need an experimental routing daemon supporting it (pimd or
|
|
gated-5). This routing protocol is not used widely, so say N unless
|
|
you want to play with it.
|
|
|
|
config SYN_COOKIES
|
|
bool "IP: TCP syncookie support"
|
|
---help---
|
|
Normal TCP/IP networking is open to an attack known as "SYN
|
|
flooding". This denial-of-service attack prevents legitimate remote
|
|
users from being able to connect to your computer during an ongoing
|
|
attack and requires very little work from the attacker, who can
|
|
operate from anywhere on the Internet.
|
|
|
|
SYN cookies provide protection against this type of attack. If you
|
|
say Y here, the TCP/IP stack will use a cryptographic challenge
|
|
protocol known as "SYN cookies" to enable legitimate users to
|
|
continue to connect, even when your machine is under attack. There
|
|
is no need for the legitimate users to change their TCP/IP software;
|
|
SYN cookies work transparently to them. For technical information
|
|
about SYN cookies, check out <http://cr.yp.to/syncookies.html>.
|
|
|
|
If you are SYN flooded, the source address reported by the kernel is
|
|
likely to have been forged by the attacker; it is only reported as
|
|
an aid in tracing the packets to their actual source and should not
|
|
be taken as absolute truth.
|
|
|
|
SYN cookies may prevent correct error reporting on clients when the
|
|
server is really overloaded. If this happens frequently better turn
|
|
them off.
|
|
|
|
If you say Y here, you can disable SYN cookies at run time by
|
|
saying Y to "/proc file system support" and
|
|
"Sysctl support" below and executing the command
|
|
|
|
echo 0 > /proc/sys/net/ipv4/tcp_syncookies
|
|
|
|
after the /proc file system has been mounted.
|
|
|
|
If unsure, say N.
|
|
|
|
config NET_IPVTI
|
|
tristate "Virtual (secure) IP: tunneling"
|
|
select INET_TUNNEL
|
|
select NET_IP_TUNNEL
|
|
depends on INET_XFRM_MODE_TUNNEL
|
|
---help---
|
|
Tunneling means encapsulating data of one protocol type within
|
|
another protocol and sending it over a channel that understands the
|
|
encapsulating protocol. This can be used with xfrm mode tunnel to give
|
|
the notion of a secure tunnel for IPSEC and then use routing protocol
|
|
on top.
|
|
|
|
config NET_UDP_TUNNEL
|
|
tristate
|
|
select NET_IP_TUNNEL
|
|
default n
|
|
|
|
config NET_FOU
|
|
tristate "IP: Foo (IP protocols) over UDP"
|
|
select XFRM
|
|
select NET_UDP_TUNNEL
|
|
---help---
|
|
Foo over UDP allows any IP protocol to be directly encapsulated
|
|
over UDP include tunnels (IPIP, GRE, SIT). By encapsulating in UDP
|
|
network mechanisms and optimizations for UDP (such as ECMP
|
|
and RSS) can be leveraged to provide better service.
|
|
|
|
config NET_FOU_IP_TUNNELS
|
|
bool "IP: FOU encapsulation of IP tunnels"
|
|
depends on NET_IPIP || NET_IPGRE || IPV6_SIT
|
|
select NET_FOU
|
|
---help---
|
|
Allow configuration of FOU or GUE encapsulation for IP tunnels.
|
|
When this option is enabled IP tunnels can be configured to use
|
|
FOU or GUE encapsulation.
|
|
|
|
config INET_AH
|
|
tristate "IP: AH transformation"
|
|
select XFRM_ALGO
|
|
select CRYPTO
|
|
select CRYPTO_HMAC
|
|
select CRYPTO_MD5
|
|
select CRYPTO_SHA1
|
|
---help---
|
|
Support for IPsec AH.
|
|
|
|
If unsure, say Y.
|
|
|
|
config INET_ESP
|
|
tristate "IP: ESP transformation"
|
|
select XFRM_ALGO
|
|
select CRYPTO
|
|
select CRYPTO_AUTHENC
|
|
select CRYPTO_HMAC
|
|
select CRYPTO_MD5
|
|
select CRYPTO_CBC
|
|
select CRYPTO_SHA1
|
|
select CRYPTO_DES
|
|
select CRYPTO_ECHAINIV
|
|
---help---
|
|
Support for IPsec ESP.
|
|
|
|
If unsure, say Y.
|
|
|
|
config INET_IPCOMP
|
|
tristate "IP: IPComp transformation"
|
|
select INET_XFRM_TUNNEL
|
|
select XFRM_IPCOMP
|
|
---help---
|
|
Support for IP Payload Compression Protocol (IPComp) (RFC3173),
|
|
typically needed for IPsec.
|
|
|
|
If unsure, say Y.
|
|
|
|
config INET_XFRM_TUNNEL
|
|
tristate
|
|
select INET_TUNNEL
|
|
default n
|
|
|
|
config INET_TUNNEL
|
|
tristate
|
|
default n
|
|
|
|
config INET_XFRM_MODE_TRANSPORT
|
|
tristate "IP: IPsec transport mode"
|
|
default y
|
|
select XFRM
|
|
---help---
|
|
Support for IPsec transport mode.
|
|
|
|
If unsure, say Y.
|
|
|
|
config INET_XFRM_MODE_TUNNEL
|
|
tristate "IP: IPsec tunnel mode"
|
|
default y
|
|
select XFRM
|
|
---help---
|
|
Support for IPsec tunnel mode.
|
|
|
|
If unsure, say Y.
|
|
|
|
config INET_XFRM_MODE_BEET
|
|
tristate "IP: IPsec BEET mode"
|
|
default y
|
|
select XFRM
|
|
---help---
|
|
Support for IPsec BEET mode.
|
|
|
|
If unsure, say Y.
|
|
|
|
config INET_DIAG
|
|
tristate "INET: socket monitoring interface"
|
|
default y
|
|
---help---
|
|
Support for INET (TCP, DCCP, etc) socket monitoring interface used by
|
|
native Linux tools such as ss. ss is included in iproute2, currently
|
|
downloadable at:
|
|
|
|
http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2
|
|
|
|
If unsure, say Y.
|
|
|
|
config INET_TCP_DIAG
|
|
depends on INET_DIAG
|
|
def_tristate INET_DIAG
|
|
|
|
config INET_UDP_DIAG
|
|
tristate "UDP: socket monitoring interface"
|
|
depends on INET_DIAG && (IPV6 || IPV6=n)
|
|
default n
|
|
---help---
|
|
Support for UDP socket monitoring interface used by the ss tool.
|
|
If unsure, say Y.
|
|
|
|
config INET_DIAG_DESTROY
|
|
bool "INET: allow privileged process to administratively close sockets"
|
|
depends on INET_DIAG
|
|
default n
|
|
---help---
|
|
Provides a SOCK_DESTROY operation that allows privileged processes
|
|
(e.g., a connection manager or a network administration tool such as
|
|
ss) to close sockets opened by other processes. Closing a socket in
|
|
this way interrupts any blocking read/write/connect operations on
|
|
the socket and causes future socket calls to behave as if the socket
|
|
had been disconnected.
|
|
If unsure, say N.
|
|
|
|
menuconfig TCP_CONG_ADVANCED
|
|
bool "TCP: advanced congestion control"
|
|
---help---
|
|
Support for selection of various TCP congestion control
|
|
modules.
|
|
|
|
Nearly all users can safely say no here, and a safe default
|
|
selection will be made (CUBIC with new Reno as a fallback).
|
|
|
|
If unsure, say N.
|
|
|
|
if TCP_CONG_ADVANCED
|
|
|
|
config TCP_CONG_BIC
|
|
tristate "Binary Increase Congestion (BIC) control"
|
|
default m
|
|
---help---
|
|
BIC-TCP is a sender-side only change that ensures a linear RTT
|
|
fairness under large windows while offering both scalability and
|
|
bounded TCP-friendliness. The protocol combines two schemes
|
|
called additive increase and binary search increase. When the
|
|
congestion window is large, additive increase with a large
|
|
increment ensures linear RTT fairness as well as good
|
|
scalability. Under small congestion windows, binary search
|
|
increase provides TCP friendliness.
|
|
See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
|
|
|
|
config TCP_CONG_CUBIC
|
|
tristate "CUBIC TCP"
|
|
default y
|
|
---help---
|
|
This is version 2.0 of BIC-TCP which uses a cubic growth function
|
|
among other techniques.
|
|
See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
|
|
|
|
config TCP_CONG_WESTWOOD
|
|
tristate "TCP Westwood+"
|
|
default m
|
|
---help---
|
|
TCP Westwood+ is a sender-side only modification of the TCP Reno
|
|
protocol stack that optimizes the performance of TCP congestion
|
|
control. It is based on end-to-end bandwidth estimation to set
|
|
congestion window and slow start threshold after a congestion
|
|
episode. Using this estimation, TCP Westwood+ adaptively sets a
|
|
slow start threshold and a congestion window which takes into
|
|
account the bandwidth used at the time congestion is experienced.
|
|
TCP Westwood+ significantly increases fairness wrt TCP Reno in
|
|
wired networks and throughput over wireless links.
|
|
|
|
config TCP_CONG_HTCP
|
|
tristate "H-TCP"
|
|
default m
|
|
---help---
|
|
H-TCP is a send-side only modifications of the TCP Reno
|
|
protocol stack that optimizes the performance of TCP
|
|
congestion control for high speed network links. It uses a
|
|
modeswitch to change the alpha and beta parameters of TCP Reno
|
|
based on network conditions and in a way so as to be fair with
|
|
other Reno and H-TCP flows.
|
|
|
|
config TCP_CONG_HSTCP
|
|
tristate "High Speed TCP"
|
|
default n
|
|
---help---
|
|
Sally Floyd's High Speed TCP (RFC 3649) congestion control.
|
|
A modification to TCP's congestion control mechanism for use
|
|
with large congestion windows. A table indicates how much to
|
|
increase the congestion window by when an ACK is received.
|
|
For more detail see http://www.icir.org/floyd/hstcp.html
|
|
|
|
config TCP_CONG_HYBLA
|
|
tristate "TCP-Hybla congestion control algorithm"
|
|
default n
|
|
---help---
|
|
TCP-Hybla is a sender-side only change that eliminates penalization of
|
|
long-RTT, large-bandwidth connections, like when satellite legs are
|
|
involved, especially when sharing a common bottleneck with normal
|
|
terrestrial connections.
|
|
|
|
config TCP_CONG_VEGAS
|
|
tristate "TCP Vegas"
|
|
default n
|
|
---help---
|
|
TCP Vegas is a sender-side only change to TCP that anticipates
|
|
the onset of congestion by estimating the bandwidth. TCP Vegas
|
|
adjusts the sending rate by modifying the congestion
|
|
window. TCP Vegas should provide less packet loss, but it is
|
|
not as aggressive as TCP Reno.
|
|
|
|
config TCP_CONG_NV
|
|
tristate "TCP NV"
|
|
default n
|
|
---help---
|
|
TCP NV is a follow up to TCP Vegas. It has been modified to deal with
|
|
10G networks, measurement noise introduced by LRO, GRO and interrupt
|
|
coalescence. In addition, it will decrease its cwnd multiplicatively
|
|
instead of linearly.
|
|
|
|
Note that in general congestion avoidance (cwnd decreased when # packets
|
|
queued grows) cannot coexist with congestion control (cwnd decreased only
|
|
when there is packet loss) due to fairness issues. One scenario when they
|
|
can coexist safely is when the CA flows have RTTs << CC flows RTTs.
|
|
|
|
For further details see http://www.brakmo.org/networking/tcp-nv/
|
|
|
|
config TCP_CONG_SCALABLE
|
|
tristate "Scalable TCP"
|
|
default n
|
|
---help---
|
|
Scalable TCP is a sender-side only change to TCP which uses a
|
|
MIMD congestion control algorithm which has some nice scaling
|
|
properties, though is known to have fairness issues.
|
|
See http://www.deneholme.net/tom/scalable/
|
|
|
|
config TCP_CONG_LP
|
|
tristate "TCP Low Priority"
|
|
default n
|
|
---help---
|
|
TCP Low Priority (TCP-LP), a distributed algorithm whose goal is
|
|
to utilize only the excess network bandwidth as compared to the
|
|
``fair share`` of bandwidth as targeted by TCP.
|
|
See http://www-ece.rice.edu/networks/TCP-LP/
|
|
|
|
config TCP_CONG_VENO
|
|
tristate "TCP Veno"
|
|
default n
|
|
---help---
|
|
TCP Veno is a sender-side only enhancement of TCP to obtain better
|
|
throughput over wireless networks. TCP Veno makes use of state
|
|
distinguishing to circumvent the difficult judgment of the packet loss
|
|
type. TCP Veno cuts down less congestion window in response to random
|
|
loss packets.
|
|
See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186>
|
|
|
|
config TCP_CONG_YEAH
|
|
tristate "YeAH TCP"
|
|
select TCP_CONG_VEGAS
|
|
default n
|
|
---help---
|
|
YeAH-TCP is a sender-side high-speed enabled TCP congestion control
|
|
algorithm, which uses a mixed loss/delay approach to compute the
|
|
congestion window. It's design goals target high efficiency,
|
|
internal, RTT and Reno fairness, resilience to link loss while
|
|
keeping network elements load as low as possible.
|
|
|
|
For further details look here:
|
|
http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
|
|
|
|
config TCP_CONG_ILLINOIS
|
|
tristate "TCP Illinois"
|
|
default n
|
|
---help---
|
|
TCP-Illinois is a sender-side modification of TCP Reno for
|
|
high speed long delay links. It uses round-trip-time to
|
|
adjust the alpha and beta parameters to achieve a higher average
|
|
throughput and maintain fairness.
|
|
|
|
For further details see:
|
|
http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
|
|
|
|
config TCP_CONG_DCTCP
|
|
tristate "DataCenter TCP (DCTCP)"
|
|
default n
|
|
---help---
|
|
DCTCP leverages Explicit Congestion Notification (ECN) in the network to
|
|
provide multi-bit feedback to the end hosts. It is designed to provide:
|
|
|
|
- High burst tolerance (incast due to partition/aggregate),
|
|
- Low latency (short flows, queries),
|
|
- High throughput (continuous data updates, large file transfers) with
|
|
commodity, shallow-buffered switches.
|
|
|
|
All switches in the data center network running DCTCP must support
|
|
ECN marking and be configured for marking when reaching defined switch
|
|
buffer thresholds. The default ECN marking threshold heuristic for
|
|
DCTCP on switches is 20 packets (30KB) at 1Gbps, and 65 packets
|
|
(~100KB) at 10Gbps, but might need further careful tweaking.
|
|
|
|
For further details see:
|
|
http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
|
|
|
|
config TCP_CONG_CDG
|
|
tristate "CAIA Delay-Gradient (CDG)"
|
|
default n
|
|
---help---
|
|
CAIA Delay-Gradient (CDG) is a TCP congestion control that modifies
|
|
the TCP sender in order to:
|
|
|
|
o Use the delay gradient as a congestion signal.
|
|
o Back off with an average probability that is independent of the RTT.
|
|
o Coexist with flows that use loss-based congestion control.
|
|
o Tolerate packet loss unrelated to congestion.
|
|
|
|
For further details see:
|
|
D.A. Hayes and G. Armitage. "Revisiting TCP congestion control using
|
|
delay gradients." In Networking 2011. Preprint: http://goo.gl/No3vdg
|
|
|
|
config TCP_CONG_BBR
|
|
tristate "BBR TCP"
|
|
default n
|
|
---help---
|
|
|
|
BBR (Bottleneck Bandwidth and RTT) TCP congestion control aims to
|
|
maximize network utilization and minimize queues. It builds an explicit
|
|
model of the the bottleneck delivery rate and path round-trip
|
|
propagation delay. It tolerates packet loss and delay unrelated to
|
|
congestion. It can operate over LAN, WAN, cellular, wifi, or cable
|
|
modem links. It can coexist with flows that use loss-based congestion
|
|
control, and can operate with shallow buffers, deep buffers,
|
|
bufferbloat, policers, or AQM schemes that do not provide a delay
|
|
signal. It requires the fq ("Fair Queue") pacing packet scheduler.
|
|
|
|
choice
|
|
prompt "Default TCP congestion control"
|
|
default DEFAULT_CUBIC
|
|
help
|
|
Select the TCP congestion control that will be used by default
|
|
for all connections.
|
|
|
|
config DEFAULT_BIC
|
|
bool "Bic" if TCP_CONG_BIC=y
|
|
|
|
config DEFAULT_CUBIC
|
|
bool "Cubic" if TCP_CONG_CUBIC=y
|
|
|
|
config DEFAULT_HTCP
|
|
bool "Htcp" if TCP_CONG_HTCP=y
|
|
|
|
config DEFAULT_HYBLA
|
|
bool "Hybla" if TCP_CONG_HYBLA=y
|
|
|
|
config DEFAULT_VEGAS
|
|
bool "Vegas" if TCP_CONG_VEGAS=y
|
|
|
|
config DEFAULT_VENO
|
|
bool "Veno" if TCP_CONG_VENO=y
|
|
|
|
config DEFAULT_WESTWOOD
|
|
bool "Westwood" if TCP_CONG_WESTWOOD=y
|
|
|
|
config DEFAULT_DCTCP
|
|
bool "DCTCP" if TCP_CONG_DCTCP=y
|
|
|
|
config DEFAULT_CDG
|
|
bool "CDG" if TCP_CONG_CDG=y
|
|
|
|
config DEFAULT_BBR
|
|
bool "BBR" if TCP_CONG_BBR=y
|
|
|
|
config DEFAULT_RENO
|
|
bool "Reno"
|
|
endchoice
|
|
|
|
endif
|
|
|
|
config TCP_CONG_CUBIC
|
|
tristate
|
|
depends on !TCP_CONG_ADVANCED
|
|
default y
|
|
|
|
config DEFAULT_TCP_CONG
|
|
string
|
|
default "bic" if DEFAULT_BIC
|
|
default "cubic" if DEFAULT_CUBIC
|
|
default "htcp" if DEFAULT_HTCP
|
|
default "hybla" if DEFAULT_HYBLA
|
|
default "vegas" if DEFAULT_VEGAS
|
|
default "westwood" if DEFAULT_WESTWOOD
|
|
default "veno" if DEFAULT_VENO
|
|
default "reno" if DEFAULT_RENO
|
|
default "dctcp" if DEFAULT_DCTCP
|
|
default "cdg" if DEFAULT_CDG
|
|
default "cubic"
|
|
|
|
config TCP_MD5SIG
|
|
bool "TCP: MD5 Signature Option support (RFC2385)"
|
|
select CRYPTO
|
|
select CRYPTO_MD5
|
|
---help---
|
|
RFC2385 specifies a method of giving MD5 protection to TCP sessions.
|
|
Its main (only?) use is to protect BGP sessions between core routers
|
|
on the Internet.
|
|
|
|
If unsure, say N.
|