ASR9000 and it’s IOS XR required administrator to apply routing policy for every neighbor. This behavior is different from IOS where if no policy were applied router accepts and sends all prefixes without limitation. So if we make following configuration:
router bgp 65374
neighbor 10.129.11.51
remote-as 1234
ebgp-multihop 10
update-source Bundle-Ether1.260
graceful-restart
address-family ipv4 unicast
soft-reconfiguration inbound always
router will inform us, that no prefixes will be send nor received on this session
RP/0/RSP0/CPU0:Aug 20 08:56:13.388 : bgp[137]: %ROUTING-BGP-6-NBR_NOPOLICY : No inbound IPv4 Unicast policy is configured for eBGP neighbor 10.129.11.51.
No IPv4 Unicast prefixes will be accepted from the neighbor until inbound policy is configured.
RP/0/RSP0/CPU0:Aug 20 08:56:13.388 : bgp[137]: %ROUTING-BGP-6-NBR_NOPOLICY : No outbound IPv4 Unicast policy is configured for eBGP neighbor 10.129.11.51.
No IPv4 Unicast prefixes will be sent to the neighbor until outbound policy is configured.
So proper configuration always have to contain policy attached to neighbor in proper address-family. In following example we’re making router send and accept all prefixes
route-policy Accept-All
pass
end-policy
!
router bgp 65374
neighbor 10.129.11.51
remote-as 1234
ebgp-multihop 10
update-source Bundle-Ether1.260
address-family ipv4 unicast
route-policy Accept-All in
route-policy Accept-All out
soft-reconfiguration inbound always
update: As my friend considered this is default behavior for eBGP peers only, for iBGP it works like in in standard IOS and all prefixes are passed to neighbors by default.