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diff --git a/src/plugins/lb/lb_plugin_doc.md b/src/plugins/lb/lb_plugin_doc.md deleted file mode 100644 index 5f6538974e9..00000000000 --- a/src/plugins/lb/lb_plugin_doc.md +++ /dev/null @@ -1,192 +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, -which 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). - -There are four encap types to steer traffic to different ASs: -1). IPv4+GRE ad IPv6+GRE encap types: -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. - -2). IPv4+L3DSR encap types: -L3DSR is used to overcome Layer 2 limitations of Direct Server Return Load Balancing. -It maps VIP to DSCP bits, and reuse TOS bits to transfer DSCP bits -to server, and then server will get VIP from DSCP-to-VIP mapping. - -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 or IPv4+L3DSR). -Meaning that for a given VIP, all AS addresses must be of the same family. - -3). IPv4/IPv6 + NAT4/NAT6 encap types: -This type provides kube-proxy data plane on user space, -which is used to replace linux kernel's kube-proxy based on iptables. - -Currently, load balancer plugin supports three service types: -a) Cluster IP plus Port: support any protocols, including TCP, UDP. -b) Node IP plus Node Port: currently only support UDP. -c) External Load Balancer. - -For Cluster IP plus Port case: -kube-proxy is configured with a set of Virtual IPs (VIP, which can be -prefixes), and for each VIP, with a set of AS addresses (ASs). - -For a specific session received for a given VIP (or VIP prefix), -first packet selects a AS according to internal load balancing algorithm, -then does DNAT operation and sent to chosen AS. -At the same time, will create a session entry to store AS chosen result. -Following packets for that session will look up session table first, -which ensures that a given session will always be routed to the same AS. - -For returned packet from AS, it will do SNAT operation and sent out. - -Please refer to below for details: -https://schd.ws/hosted_files/ossna2017/1e/VPP_K8S_GTPU_OSSNA.pdf - - -## Performance - -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 performance 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 for GRE4 mode. - or Node IP4 address for NAT4 mode. - -ip6-src-address: the source address used to send encap. packets using IPv6 for GRE6 mode. - or Node IP6 address for NAT6 mode. - -buckets: the *per-thread* established-connections-table number of buckets. - -timeout: the number of seconds a connection will remain in the - established-connections-table while no packet for this flow - is received. - -### Configure the VIPs - - lb vip <prefix> [encap (gre6|gre4|l3dsr|nat4|nat6)] \ - [dscp <n>] [port <n> target_port <n> node_port <n>] [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. -Encap l3dsr and dscp is used to map VIP to dscp bit and rewrite DSCP bit in packets. -So the selected server could get VIP from DSCP bit in this packet and perform DSR. -Encap nat4/nat6 and port/target_port/node_port is used to do kube-proxy data plane. - -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 - lb vip 100.0.0.0/8 encap l3dsr dscp 2 new_len 32 - lb vip 90.1.2.1/32 encap nat4 port 3306 target_port 3307 node_port 30964 new_len 1024 - lb vip 2004::/16 encap nat6 port 6306 target_port 6307 node_port 30966 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 - -### Configure SNAT - - lb set interface nat4 in <intfc> [del] - -Set SNAT feature in a specific interface. -(applicable in NAT4 mode only) - - lb set interface nat6 in <intfc> [del] - -Set SNAT feature in a specific interface. -(applicable in NAT6 mode only) - -## 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. - |