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diff --git a/plugins/lb-plugin/lb_plugin_doc.md b/plugins/lb-plugin/lb_plugin_doc.md deleted file mode 100644 index c7885ffb837..00000000000 --- a/plugins/lb-plugin/lb_plugin_doc.md +++ /dev/null @@ -1,141 +0,0 @@ -# Load Balancer plugin for VPP {#lb_plugin_doc} - -## Version - -The load balancer plugin is currently in *beta* version. -Both CLIs and APIs are subject to *heavy* changes. -Wich also means feedback is really welcome regarding features, apis, etc... - -## Overview - -This plugin provides load balancing for VPP in a way that is largely inspired -from Google's MagLev: http://research.google.com/pubs/pub44824.html - -The load balancer is configured with a set of Virtual IPs (VIP, which can be -prefixes), and for each VIP, with a set of Application Server addresses (ASs). - -Traffic received for a given VIP (or VIP prefix) is tunneled using GRE towards -the different ASs in a way that (tries to) ensure that a given session will -always be tunneled to the same AS. - -Both VIPs or ASs can be IPv4 or IPv6, but for a given VIP, all ASs must be using -the same encap. type (i.e. IPv4+GRE or IPv6+GRE). Meaning that for a given VIP, -all AS addresses must be of the same family. - -## Performances - -The load balancer has been tested up to 1 millions flows and still forwards more -than 3Mpps per core in such circumstances. -Although 3Mpps seems already good, it is likely that performances will be improved -in next versions. - -## Configuration - -### Global LB parameters - -The load balancer needs to be configured with some parameters: - - lb conf [ip4-src-address <addr>] [ip6-src-address <addr>] - [buckets <n>] [timeout <s>] - -ip4-src-address: the source address used to send encap. packets using IPv4. - -ip6-src-address: the source address used to send encap. packets using IPv6. - -buckets: the *per-thread* established-connexions-table number of buckets. - -timeout: the number of seconds a connection will remain in the - established-connexions-table while no packet for this flow - is received. - - -### Configure the VIPs - - lb vip <prefix> [encap (gre6|gre4)] [new_len <n>] [del] - -new_len is the size of the new-connection-table. It should be 1 or 2 orders of -magnitude bigger than the number of ASs for the VIP in order to ensure a good -load balancing. - -Examples: - - lb vip 2002::/16 encap gre6 new_len 1024 - lb vip 2003::/16 encap gre4 new_len 2048 - lb vip 80.0.0.0/8 encap gre6 new_len 16 - lb vip 90.0.0.0/8 encap gre4 new_len 1024 - -### Configure the ASs (for each VIP) - - lb as <vip-prefix> [<address> [<address> [...]]] [del] - -You can add (or delete) as many ASs at a time (for a single VIP). -Note that the AS address family must correspond to the VIP encap. IP family. - -Examples: - - lb as 2002::/16 2001::2 2001::3 2001::4 - lb as 2003::/16 10.0.0.1 10.0.0.2 - lb as 80.0.0.0/8 2001::2 - lb as 90.0.0.0/8 10.0.0.1 - - - -## Monitoring - -The plugin provides quite a bunch of counters and information. -These are still subject to quite significant changes. - - show lb - show lb vip - show lb vip verbose - - show node counters - - -## Design notes - -### Multi-Threading - -MagLev is a distributed system which pseudo-randomly generates a -new-connections-table based on AS names such that each server configured with -the same set of ASs ends up with the same table. Connection stickyness is then -ensured with an established-connections-table. Using ECMP, it is assumed (but -not relied on) that servers will mostly receive traffic for different flows. - -This implementation pushes the parallelism a little bit further by using -one established-connections table per thread. This is equivalent to assuming -that RSS will make a job similar to ECMP, and is pretty useful as threads don't -need to get a lock in order to write in the table. - -### Hash Table - -A load balancer requires an efficient read and write hash table. The hash table -used by ip6-forward is very read-efficient, but not so much for writing. In -addition, it is not a big deal if writing into the hash table fails (again, -MagLev uses a flow table but does not heaviliy relies on it). - -The plugin therefore uses a very specific (and stupid) hash table. - - Fixed (and power of 2) number of buckets (configured at runtime) - - Fixed (and power of 2) elements per buckets (configured at compilation time) - -### Reference counting - -When an AS is removed, there is two possible ways to react. - - Keep using the AS for established connections - - Change AS for established connections (likely to cause error for TCP) - -In the first case, although an AS is removed from the configuration, its -associated state needs to stay around as long as it is used by at least one -thread. - -In order to avoid locks, a specific reference counter is used. The design is quite -similar to clib counters but: - - It is possible to decrease the value - - Summing will not zero the per-thread counters - - Only the thread can reallocate its own counters vector (to avoid concurrency issues) - -This reference counter is lock free, but reading a count of 0 does not mean -the value can be freed unless it is ensured by *other* means that no other thread -is concurrently referencing the object. In the case of this plugin, it is assumed -that no concurrent event will take place after a few seconds. - |