tcp_bbr: add BBR congestion control

[linux-2.6-microblaze.git] / net / ipv4 / Kconfig

#
# 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.