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+.. _snmp-support:
+
+************
+SNMP Support
+************
+
+:abbr:`SNMP (Simple Network Managing Protocol)` is a widely implemented feature
+for collecting network information from router and/or host. FRR itself does
+not support SNMP agent (server daemon) functionality but is able to connect to
+a SNMP agent using the the AgentX protocol (:rfc:`2741`) and make the
+routing protocol MIBs available through it.
+
+Note that SNMP Support needs to be enabled at compile-time and loaded as module
+on daemon startup. Refer to :ref:`loadable-module-support` on the latter.  If
+you do not start the daemons with snmp module support snmp will not work
+properly.
+
+.. _getting-and-installing-an-snmp-agent:
+
+Getting and installing an SNMP agent
+====================================
+
+The supported SNMP agent is AgentX. We recommend to use
+the latest version of `net-snmp` which was formerly known as `ucd-snmp`. It is
+free and open software and available at `http://www.net-snmp.org/ <http://www.net-snmp.org/>`_
+and as binary package for most Linux distributions.
+
+.. _net-smtp-configuration:
+
+NET-SNMP configuration
+======================
+
+Routers with a heavy amount of routes (e.g. BGP full table) might experience
+problems with a hanging vtysh from time to time, 100% CPU on the snmpd or
+even crashes of the frr daemon(s) due to stalls within AgentX. Once snmp
+agents connects they start receiving a heavy amount of SNMP data (all the
+routes) which cannot be handled quick enough. It's recommended (by several
+vendors as well) to exclude these OID's unless you really need them, which
+can be achieved by amending the default view from SNMP
+
+:file:`/etc/snmp/snmpd.conf`:
+
+::
+
+   # This is the default view
+   view all    included  .1 80
+   # Remove ipRouteTable from view
+   view all    excluded  .1.3.6.1.2.1.4.21
+   # Remove ipNetToMediaTable from view
+   view all    excluded  .1.3.6.1.2.1.4.22
+   # Remove ipNetToPhysicalPhysAddress from view
+   view all    excluded  .1.3.6.1.2.1.4.35
+   # Remove ipCidrRouteTable  from view
+   view all    excluded  .1.3.6.1.2.1.4.24
+   # Optionally protect SNMP private/secret values
+   view all    excluded  .1.3.6.1.6.3.15
+   view all    excluded  .1.3.6.1.6.3.16
+   view all    excluded  .1.3.6.1.6.3.18
+   # Optionally allow SNMP public info (sysName, location, etc)
+   view system included  .iso.org.dod.internet.mgmt.mib-2.system
+
+
+.. _agentx-configuration:
+
+AgentX configuration
+====================
+
+.. program:: configure
+
+To enable AgentX protocol support, FRR must have been build with the
+:option:`--enable-snmp` or `--enable-snmp=agentx` option. Both the
+master SNMP agent (snmpd) and each of the FRR daemons must be configured. In
+:file:`/etc/snmp/snmpd.conf`, the ``master agentx`` directive should be added.
+In each of the FRR daemons, ``agentx`` command will enable AgentX support.
+
+:file:`/etc/snmp/zebra.conf`:
+
+::
+
+   #
+   # example access restrictions setup
+   #
+   com2sec readonly default public
+   group MyROGroup v1 readonly
+   view all included .1 80
+   access MyROGroup "" any noauth exact all none none
+   #
+   # enable master agent for AgentX subagents
+   #
+   master agentx
+
+:file:`/etc/frr/ospfd.conf:`
+
+   .. code-block:: frr
+
+      ! ... the rest of ospfd.conf has been omitted for clarity ...
+      !
+      agentx
+      !
+
+
+Upon successful connection, you should get something like this in the log of
+each FRR daemons:
+
+::
+
+   2012/05/25 11:39:08 ZEBRA: snmp[info]: NET-SNMP version 5.4.3 AgentX subagent connected
+
+
+Then, you can use the following command to check everything works as expected:
+
+::
+
+   # snmpwalk -c public -v1 localhost .1.3.6.1.2.1.14.1.1
+   OSPF-MIB::ospfRouterId.0 = IpAddress: 192.168.42.109
+   [...]
+
+
+The AgentX protocol can be transported over a Unix socket or using TCP or UDP.
+It usually defaults to a Unix socket and depends on how NetSNMP was built. If
+need to configure FRR to use another transport, you can configure it through
+:file:`/etc/snmp/frr.conf`:
+
+::
+
+   [snmpd]
+   # Use a remote master agent
+   agentXSocket tcp:192.168.15.12:705
+
+
+Here is the syntax for using AgentX:
+
+.. clicmd:: agentx
+
+
+.. include:: snmptrap.rst