routing protocol, and it makes routing decisions based on paths, network policies, or rule-sets configured
by a network administrator.
7.2.4.1. Description
BGP splits the network into Autonomous Systems (AS) which are identified by a specific number. Indi-
vidual BGP routers are interconnected with their neighbors using TCP connections. Any connection
can travel over multiple hops. Any connection can be secured using MD5 signatures.
Connections inside the AS are called ‘internal’ (iBGP):
• All BGP routers within given AS must be fully interconnected – every router must have connection
to all other routers.
• It is possible to define ‘Route reflectors’ – they must be fully interconnected. The other routers behave
as Route reflector clients and they need a connection to their reflector only. Route reflector and its
clients form a ‘cluster’. It is possible to create a cluster with multiple Route reflectors for the purpose
of backup.
• The iBGP router having a higher local preference will be preferred during the internal AS path selection.
Connections to another AS are called ‘external’ (eBGP):
• It is possible to communicate from the router to the neighbor AS the MED (Multi-Exit Discriminator)
metric designating which of the AS border routers will be used as an input point.
When the routing rules are spread across the multiple AS, those AS are added into the accumulated
path (BGP path). Path length is the primary criteria during the decision which of the routing rules will
be used.
It is possible to prescribe routing rules toward this router which will be spread across the network
(Static rules).
It is possible to control the routing rules which are imported into the RipEX unit from the BGP protocol
and those that are exported into the BGP protocol from the unit by using ‘filters’.
Import IGP filter – controls which of the routing rules from the BGP are accepted to the dynamic
routing table and how
Export IGP filter – controls which of the routing rules from the dynamic routing table are exported to
the BGP and how
Import OUT filter – controls which of the routing rules from the other AS are accepted to the BGP
and how
Export OUT filter – controls which of the routing rules are exported from the BGP to other AS and
how
Routing rules passed on between iBGP and BGP tables are not filtered
7.2.4.2. Common - Common settings
Active
List box {On; Off}, default = "Off"Enables the dynamic routing and the BGP protocol.
RipEX2 Radio modem & Router – © RACOM s.r.o.
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Settings
