Routing – BGP peer group type in Junos

bgpjuniperjuniper-junosrouting

In Juniper routers running the Junos operating system, one can set the BGP peer group type either to external or internal:

[edit]
root@M10i# set groups customer protocols bgp group customer-BGP-group type ?           
Possible completions:
  external             EBGP group
  internal             IBGP group
[edit]
root@M10i# set groups customer protocols bgp group customer-BGP-group type

Default should be external. I know that if the type is set to external, then the peer AS can not be the same as the local AS, and if the type is set to internal, then the peer AS must be the same as the local AS.

Does this change anything else?

Best Answer

Because the AS-PATH attribute is not updated in iBGP, in order to prevent routing loops, an iBGP router will not advertise routes learned from an iBGP peer.

BGP speakers within a single AS (iBGP) must be connected in a full mesh or use a mitigation to prevent traffic from being blackholed.

Some BGP attributes cannot be sent from one AS to a different AS, and some BGP attributes only have meaning between different ASes.

Related Topic