Date: Thu, 3 May 2012 13:08:11 +0000 (UTC) From: Benjamin Kaduk <bjk@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r234953 - head/share/man/man4 Message-ID: <201205031308.q43D8CCq039903@svn.freebsd.org>
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Author: bjk (doc committer) Date: Thu May 3 13:08:11 2012 New Revision: 234953 URL: http://svn.freebsd.org/changeset/base/234953 Log: Grammar and markup fixes. PR: docs/159854 Approved by: hrs (mentor) Modified: head/share/man/man4/carp.4 Modified: head/share/man/man4/carp.4 ============================================================================== --- head/share/man/man4/carp.4 Thu May 3 10:38:02 2012 (r234952) +++ head/share/man/man4/carp.4 Thu May 3 13:08:11 2012 (r234953) @@ -42,8 +42,8 @@ addresses are always available. .Pp To use .Nm , -the administrator needs to configure at minimum a common virtual host ID -(vhid) and attach at least one IP address to this vhid on each machine which +the administrator needs to configure at a minimum a common virtual host ID +(vhid), and attach at least one IP address to this vhid on each machine which is to take part in the virtual group. Additional parameters can also be set on a per-vhid basis: .Cm advbase @@ -72,13 +72,13 @@ Both and .Cm advskew are put inside CARP advertisements. -These configurations can be done using +These values can be configured using .Xr ifconfig 8 , or through the .Dv SIOCSVH .Xr ioctl 2 . .Pp -CARP virtual hosts can be configured on multicast capable interfaces: Ethernet, +CARP virtual hosts can be configured on multicast-capable interfaces: Ethernet, layer 2 VLAN, FDDI and Token Ring. An arbitrary number of virtual host IDs can be configured on an interface. An arbitrary number of IPv4 or IPv6 addresses can be attached to a particular @@ -91,7 +91,7 @@ elections independently. .Pp Additionally, there are a number of global parameters which can be set using .Xr sysctl 8 : -.Bl -tag -width ".Va net.inet.carp.preempt" +.Bl -tag -width ".Va net.inet.carp.ifdown_demotion_factor" .It Va net.inet.carp.allow Accept incoming .Nm @@ -103,14 +103,17 @@ When enabled, a vhid in a backup state w is announcing itself with a lower advskew. Disabled by default. .It Va net.inet.carp.log -Value of 0 disables any logging. -Value of 1 enables logging state changes of +Determines what events relating to +.Nm +interfaces are logged. +A value of 0 disables any logging. +A value of 1 enables logging state changes of .Nm vhids. Values above 1 enable logging of bad .Nm packets. -Default value is 1. +The default value is 1. .It Va net.inet.carp.demotion This value shows current level of CARP demotion. The value is added to the actual advskew sent in announcements for @@ -123,44 +126,48 @@ running a vhid goes down, or while the .Xr pfsync 4 interface is not synchronized. The demotion value is writable, so that user may alter it -depending on some external conditions, for example on status of some +depending on some external conditions, for example on the status of some daemon utility. -However, altering the value should be performed with care, do +However, altering the value should be performed with care, so as to not conflict with subsystems that adjust demotion factor automatically: .Nm and .Xr pfsync 4 . .It Va net.inet.carp.ifdown_demotion_factor -Value added to +This value is added to .Va net.inet.carp.demotion -when interface running a vhid goes down. -Default value is 240 (maximum advskew value). +when an interface running a vhid goes down. +The default value is 240 (the maximum advskew value). .It Va net.inet.carp.senderr_demotion_factor -Value added to +This value is added to .Va net.inet.carp.demotion when .Nm experiences errors sending its announcements. -Default value is 240 (maximum advskew value). +The default value is 240 (the maximum advskew value). .El .\".Sh ARP level load balancing -.\"The +.\"A .\".Nm -.\"has limited abilities for load balancing the incoming connections -.\"between hosts in Ethernet network. -.\"For load balancing operation, one needs several CARP interfaces that +.\"interface has limited abilities for load balancing incoming connections +.\"between hosts in an Ethernet network. +.\"For load-balancing operation, one needs several CARP interfaces that .\"are configured to the same IP address, but to a different vhids. .\"Once an ARP request is received, the CARP protocol will use a hashing .\"function against the source IP address in the ARP request to determine -.\"which vhid should this request belong to. -.\"If the corresponding CARP interface is in master state, the ARP request -.\"will be replied, otherwise it will be ignored. +.\"which vhid the request will be assigned to. +.\"If the corresponding CARP interface is the current +.\"master interface, a reply will +.\"be sent to the ARP request; +.\"otherwise it will be ignored. .\"See the .\".Sx EXAMPLES .\"section for a practical example of load balancing. .\".Pp -.\"The ARP load balancing has some limitations. +.\"The ARP load balancing implemented in +.\".Nm +.\"has some limitations. .\"First, ARP balancing only works on the local network segment. .\"It cannot balance traffic that crosses a router, because the .\"router itself will always be balanced to the same virtual host. @@ -170,10 +177,11 @@ Default value is 240 (maximum advskew va .\"is dangerous, because this creates a race condition between .\"balanced routers and a host they are serving. .\"Imagine an incoming packet creating state on the first router, being -.\"forwarded to its destination, and destination replying faster +.\"forwarded to its destination, and the destination replying faster .\"than the state information is packed and synced with the second router. .\"If the reply would be load balanced to second router, it will be -.\"dropped due to no state. +.\"dropped since the second router has not yet received information about +.\"the connection state. .Sh STATE CHANGE NOTIFICATIONS Sometimes it is useful to get notified about .Nm @@ -183,11 +191,12 @@ This can be accomplished by using hooks. Master/slave events are signalled under system .Dv CARP . -Subsystem specifies vhid and name of interface, where event occurred. -Type of the message displays new state of vhid. +The subsystem specifies the vhid and name of the interface where +the master/slave event occurred. +The type of the message displays the new state of the vhid. Please see .Xr devd.conf 5 -and +and the .Sx EXAMPLES section for more information. .Sh EXAMPLES @@ -195,8 +204,8 @@ For firewalls and routers with multiple failover all of the addresses running .Nm together, when one of the physical interfaces goes down. -This is achieved by the preempt option. -Enable it on both host A and B: +This is achieved by the use of the preempt option. +Enable it on both hosts A and B: .Pp .Dl sysctl net.inet.carp.preempt=1 .Pp @@ -295,7 +304,6 @@ The device was imported into .Fx 5.4 . In -.Fx 10.0 -the +.Fx 10.0 , .Nm was significantly rewritten, and is no longer a pseudo-interface.
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