Thanks for these output.
Original Message:
Sent: Mar 19, 2024 05:42 AM
From: torro
Subject: BGP best path
Hi
Yes of course. All IPs are fake and I hope I haven't made a typo while changing to those.
The output below is from the two CX-OVA nodes (SW01 & SW02). Connectivity for this lab is one external for the eBGP on both nodes, one connection between the two nodes and one connection to an "internal" network from both CX nodes. I'm "controlling" the inbound path from the ISP side by using BGP communities and Local Preference and as seen in the output also Local Preference to control the outbound path. The output below show that SW02 have the primary path to/from the ISP.
sw01# sho bgp ipv4 unicast
Status codes: s suppressed, d damped, h history, * valid, > best, = multipath,
i internal, e external S Stale, R Removed, a additional-paths
Origin codes: i - IGP, e - EGP, ? - incomplete
VRF : default
Local Router-ID 10.10.255.1
Network Nexthop Metric LocPrf Weight Path
*> 0.0.0.0/0 172.16.184.243 0 300 0 64513 i
* e 0.0.0.0/0 172.16.184.241 0 200 0 64513 i
*> 172.16.184.0/23 0.0.0.0 0 100 0 i
* i 172.16.184.0/23 10.10.255.2 0 100 0 i
*>i 200.200.0.0/16 172.16.184.243 2 300 0 64513 i
* e 200.200.0.0/16 172.16.184.241 0 200 0 64513 i
Total number of entries 6
sw01# sho ip route
Displaying ipv4 routes selected for forwarding
Origin Codes: C - connected, S - static, L - local
R - RIP, B - BGP, O - OSPF
Type Codes: E - External BGP, I - Internal BGP, V - VPN, EV - EVPN
IA - OSPF internal area, E1 - OSPF external type 1
E2 - OSPF external type 2
VRF: default
Prefix Nexthop Interface VRF(egress) Origin/ Distance/ Age
Type Metric
----------------------------------------------------------------------------------------------
0.0.0.0/0 10.10.254.49 1/1/3 - B/I [200/0] 00h:03m:05s
10.10.254.48/31 - 1/1/3 - C [0/0] -
10.10.254.48/32 - 1/1/3 - L [0/0] -
10.10.255.1/32 - loopback0 - L [0/0] -
10.10.255.2/32 10.10.254.49 1/1/3 - O [110/100] 00h:03m:45s
172.16.184.0/23 - blackhole - S [1/0] 00h:04m:06s
172.16.184.0/24 172.16.184.1 1/1/2 - S [1/0] 00h:04m:06s
172.16.184.0/28 - 1/1/2 - C [0/0] -
172.16.184.13/32 - 1/1/2 - L [0/0] -
172.16.184.240/31 - 1/1/1 - C [0/0] -
172.16.184.240/32 - 1/1/1 - L [0/0] -
172.16.184.242/31 10.10.254.49 1/1/3 - O [110/200] 00h:03m:45s
172.16.185.0/24 172.16.184.1 1/1/2 - S [1/0] 00h:04m:06s
200.200.0.0/16 10.10.254.49 1/1/3 - B/I [200/2] 00h:03m:05s
Total Route Count : 14
sw01#
-------------------------------------------------------------------------------
sw02# sho bgp ipv4 unicast
Status codes: s suppressed, d damped, h history, * valid, > best, = multipath,
i internal, e external S Stale, R Removed, a additional-paths
Origin codes: i - IGP, e - EGP, ? - incomplete
VRF : default
Local Router-ID 10.10.255.2
Network Nexthop Metric LocPrf Weight Path
*>e 0.0.0.0/0 172.16.184.243 0 300 0 64513 i
*> 172.16.184.0/23 0.0.0.0 0 100 0 i
* 172.16.184.0/23 10.10.255.1 0 100 0 i
*>e 200.200.0.0/16 172.16.184.243 2 300 0 64513 i
Total number of entries 4
sw02# sho ip route
Displaying ipv4 routes selected for forwarding
Origin Codes: C - connected, S - static, L - local
R - RIP, B - BGP, O - OSPF
Type Codes: E - External BGP, I - Internal BGP, V - VPN, EV - EVPN
IA - OSPF internal area, E1 - OSPF external type 1
E2 - OSPF external type 2
VRF: default
Prefix Nexthop Interface VRF(egress) Origin/ Distance/ Age
Type Metric
---------------------------------------------------------------------------------------------------------
0.0.0.0/0 172.16.184.243 1/1/1 - B/E [20/0] 00h:03m:13s
10.10.254.48/31 - 1/1/3 - C [0/0] -
10.10.254.49/32 - 1/1/3 - L [0/0] -
10.10.255.1/32 10.10.254.48 1/1/3 - O [110/100] 00h:04m:04s
10.10.255.2/32 - loopback0 - L [0/0] -
172.16.184.0/23 - blackhole - S [1/0] 00h:04m:25s
172.16.184.0/24 172.16.184.1 1/1/2 - S [1/0] 00h:04m:26s
172.16.184.0/28 - 1/1/2 - C [0/0] -
172.16.184.14/32 - 1/1/2 - L [0/0] -
172.16.184.240/31 10.10.254.48 1/1/3 - O [110/200] 00h:04m:04s
172.16.184.242/31 - 1/1/1 - C [0/0] -
172.16.184.242/32 - 1/1/1 - L [0/0] -
172.16.185.0/24 172.16.184.1 1/1/2 - S [1/0] 00h:04m:26s
200.200.0.0/16 172.16.184.243 1/1/1 - B/E [20/2] 00h:03m:13s
Total Route Count : 14
sw02#
------------------------------
Torro
Original Message:
Sent: Mar 19, 2024 04:53 AM
From: vincent.giles
Subject: BGP best path
Hello,
Would you mind sharing for the community CLI output for show bgp ipv4 unicast and sh ip route,
so that it closes the topic. Thanks.
Original Message:
Sent: Mar 18, 2024 09:31 AM
From: torro
Subject: BGP best path
It seems stable now and my original issue was my mistake. Missing was IGP routing for the eBGP interface on both Aruba-CX switches. It stable now after correcting this.
------------------------------
Torro
Original Message:
Sent: Mar 14, 2024 08:04 AM
From: torro
Subject: BGP best path
Hi
Thanks for your input. I discovered that I had an IGP error that I didnt see previously. When correcting that it looks correct now. But I don't think that should impact the BGP table, just the reachability based on the forwarding table. At the moment I have a mix of 10.09 and 10.07. I will use 10.09 on both CX nodes and do some failovers between nodes based on failures to see how it behaves.
------------------------------
Torro
Original Message:
Sent: Mar 14, 2024 05:32 AM
From: Ramaprasad Allu
Subject: BGP best path
Hi,
Can you double check if iBGP route next-hop (172.16.184.243) is reachable?
* i 0.0.0.0/0 172.16.184.243 0 300 0 64513 i
*>e 0.0.0.0/0 172.16.184.241 0 200 0 64513 i
AOS-CX supports BGP best-path selection as per standard BGP decision tree, and there are no gaps here. When BGP RIB learns same route from iBGP and eBGP sessions, by default eBGP route will get selected as best route. However, in this case you have set the LP which is second in priority so the route that has higher local-preference should get selected as best route. I think here eBGP is selected as best route may be due to next-hop 172.16.184.243 is unreachable.
Can you double check if the next-hop is reachable?
My local test-bed it is working perfectly fine.
Network Nexthop Metric LocPrf Weight Path
*>i 22.22.22.22/32 10.1.1.1 0 300 0 1 i
* e 22.22.22.22/32 12.1.1.1 0 200 0 1 i
--Ramaprasad
Original Message:
Sent: Mar 14, 2024 05:20 AM
From: torro
Subject: BGP best path
Hi
thanks for notifying. It's a bit sad though.