doc: document bgp listen ranges and md5 behavior

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>
This commit is contained in:
Quentin Young 2019-04-16 15:19:10 +00:00
parent 9e7d9a61ac
commit d79e0e085b

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@ -826,6 +826,30 @@ Defining Peers
peers ASN is the same as mine as specified under the :clicmd:`router bgp ASN` peers ASN is the same as mine as specified under the :clicmd:`router bgp ASN`
command the connection will be denied. command the connection will be denied.
.. index:: [no] bgp listen range <A.B.C.D/M|X:X::X:X/M> peer-group WORD
.. clicmd:: [no] bgp listen range <A.B.C.D/M|X:X::X:X/M> peer-group WORD
Accept connections from any peers in the specified prefix. Configuration
from the specified peer-group is used to configure these peers.
.. note::
When using BGP listen ranges, if the associated peer group has TCP MD5
authentication configured, your kernel must support this on prefixes. On
Linux, this support was added in kernel version 4.14. If your kernel does
not support this feature you will get a warning in the log file, and the
listen range will only accept connections from peers without MD5 configured.
Additionally, we have observed that when using this option at scale (several
hundred peers) the kernel may hit its option memory limit. In this situation
you will see error messages like:
``bgpd: sockopt_tcp_signature: setsockopt(23): Cannot allocate memory``
In this case you need to increase the value of the sysctl
``net.core.optmem_max`` to allow the kernel to allocate the necessary option
memory.
.. _bgp-configuring-peers: .. _bgp-configuring-peers:
Configuring Peers Configuring Peers