Solved: General BGP issue and need a help with it - Page 3

blason · ‎09-02-2022

Hi Team,

I need a help with BGP and my setup is as below. There is no cisco routers involved however I need a help on BGP issue. I have a router installed at my end and I have two ISPs terminated on those. I have then configured two IPsec tunnels with Azure and I am running BGP over IPsec.

However I noticed here that 192.168.40.0/23 route is only advertised from 169.254.21.9 and if I check routes on 169.254.21.13 I am seeing 192.168.40.0/23 is learned from Azure. However the subnet belongs to me.

show ip bgp neighbors 169.254.21.1 received-routes
Default local pref 100, local AS 65506
Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
               i internal, r RIB-failure, S Stale, R Removed
Nexthop codes: @nnn nexthop's vrf id, < announce-nh-self
Origin codes:  i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 10.1.0.0/16      169.254.21.1                           0 65515 i
***> 10.11.44.0/22    169.254.21.1                           0 65515 i**

While for other Peer

show ip bgp neighbors 169.254.22.1 received-routes
Default local pref 100, local AS 65506
Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
               i internal, r RIB-failure, S Stale, R Removed
Nexthop codes: @nnn nexthop's vrf id, < announce-nh-self
Origin codes:  i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 10.1.0.0/16      169.254.22.1                           0 65515 i
*> 10.11.44.0/22    169.254.22.1                           0 65515 65515 65515 65515 i
*> 192.168.40.0/23  169.254.22.1             0             0 65515 65506 i

If notice here 192.168.40.0/23 which is my subnet getting advertised by Azure and is sending it to me. Even If I look at the path its been received via 65515 which is Azure and then mine. This is pretty surprising and Azure if receiving with igp.

Hence wanted to know even if I am advertising the routes in Global BGP; how can I ensure that routes are being advertised to both my neighbors?
And if not how would I advertise with specific neighbor like cisco?

Hence my issue is if 169.254.21.1 goes down my traffic stops completely and I suspect is; since 192.168.40.0/23 is being learned from azure; Azure it not sending the traffic back.

Can someone please help me on this issue?

TIA

Blason R

blason · ‎09-03-2022

Hmmm - So what could be the remedy? Import

route map

and drop the traffic if it has my own AS number?

Also do you see normal that 40.0/23 is again advertised via other router?

MHM Cisco World · ‎09-04-2022

Or which is best and recommend make Azure only advertise it origin route not work as transit AS router.

blason · ‎09-04-2022

Resolved -

Made below changes

set policy prefix-list LocalSubnets rule 10 action permit
set policy prefix-list LocalSubnets rule 10 prefix 192.168.40.0/23
set policy route-map Out rule 10 action permit
set policy route-map Out rule 10 match ip address prefix-list LocalSubnets
set protocols bgp 65506 neighbor 169.254.22.1 address-family ipv4-unicast route-map export Out

Thanks a lot for your Help Guys. I really appreciate of your help @MHM Cisco World @Harold Ritter

MHM Cisco World · ‎09-04-2022

You are so so welcome