11-03-2025 03:49 AM
Hi,
So this issue I have it drives me crazy lately so my last resort is here.
I have the following topology. R4 <----> R7. Both connected through one Ethernet link in EVE-NG. The image I have is i86bi_linux-adventerprisek9-ms.156-3.M3a.bin but the same is happenning with CSR csr1000vng-universalk9.16.06.05.Everest
I establish connection between each loopback of those routers with EIGRP AS 47. After that, I run eBGP between the loopbacks (4.4.4.4 & 7.7.7.7, both /24). If I just configure eBGP and I don't advertise anything in BGP, the connection stays up. In a matter of seconds after I advertise let's say on of the loopbacks through eBGP, it happens that the neighborship goes down.
Below you can see both the logs and the debug. I want to mention that timers are the same.
Any idea why is this happenning? Is because of virtualisation? Or is something I do wrong?
*Nov 3 11:47:31.560: BGP: ses global 7.7.7.7 (0xBB8143A8:1) Keep alive timer fired. *Nov 3 11:47:31.560: BGP: 7.7.7.7 KEEPALIVE requested (bgp_keepalive_timer_expired) *Nov 3 11:47:31.560: BGP: ses global 7.7.7.7 (0xBB8143A8:1) service keepalive IO request. *Nov 3 11:47:31.560: BGP: 7.7.7.7 KEEPALIVE write request serviced in BGP_IO R4# *Nov 3 11:47:37.536: BGP: 7.7.7.7 received KEEPALIVE, length (excl. header) 0 R4# *Nov 3 11:47:51.958: BGP: 7.7.7.7 rcv message type 3, length (excl. header) 2 *Nov 3 11:47:51.958: %BGP-3-NOTIFICATION: received from neighbor 7.7.7.7 4/0 (hold time expired) 0 bytes *Nov 3 11:47:51.958: BGP: ses global 7.7.7.7 (0xBB8143A8:1) Receive NOTIFICATION 4/0 (hold time expired) 0 bytes *Nov 3 11:47:51.958: %BGP-5-NBR_RESET: Neighbor 7.7.7.7 reset (BGP Notification received) *Nov 3 11:47:51.958: BGP: ses global 7.7.7.7 (0xBB8143A8:1) Reset (BGP Notification received). *Nov 3 11:47:51.958: BGP: 7.7.7.7 went from Established to Closing *Nov 3 11:47:51.958: BGP: 7.7.7.7 reset due to BGP Notification received *Nov 3 11:47:51.958: BGP: tbl IPv4 Unicast:base Service reset requests *Nov 3 11:47:51.958: BGP: tbl IPv4 Multicast:base Service reset requests *Nov 3 11:47:51.958: BGP: tbl L2VPN E-VPN:base Service reset requests *Nov 3 11:47:51.958: BGP: tbl MVPNv4 Unicast:base Service reset requests *Nov 3 11:47:51.958: BGP: nbr_topo global 7.7.7.7 IPv4 Unicast:base (0xBB8143A8:1) NSF delete stale NSF not active *Nov 3 11:47:51.958: BGP: nbr_topo global 7.7.7.7 IPv4 Unicast:base (0xBB8143A8:1) NSF no stale paths state is NSF not active *Nov 3 11:47:51.958: BGP: nbr_topo global 7.7.7.7 IPv4 Unicast:base (0xBB8143A8:1) Resetting ALL counters. *Nov 3 11:47:51.958: BGP: 7.7.7.7 closing *Nov 3 11:47:51.958: BGP: ses global 7.7.7.7 (0xBB8143A8:1) Session close and reset neighbor 7.7.7.7 topostate *Nov 3 11:47:51.958: BGP: nbr_topo global 7.7.7.7 IPv4 Unicast:base (0xBB8143A8:1) Resetting ALL counters. *Nov 3 11:47:51.958: BGP: 7.7.7.7 went from Closing to Idle *Nov 3 11:47:51.958: %BGP-5-ADJCHANGE: neighbor 7.7.7.7 Down BGP Notification received *Nov 3 11:47:51.958: %BGP_SESSION-5-ADJCHANGE: neighbor 7.7.7.7 IPv4 Unicast topology base removed from session BGP Notification received *Nov 3 11:47:51.958: BGP: ses global 7.7.7.7 (0xBB8143A8:1) Removed topology IPv4 Unicast:base *Nov 3 11:47:51.958: BGP: ses global 7.7.7.7 (0xBB8143A8:1) Removed last topology *Nov 3 11:47:51.958: BGP: nbr global 7.7.7.7 Active open failed - route to peer is invalid *Nov 3 11:47:51.958: BGP: nbr global 7.7.7.7 Active open failed - route to peer is invalid *Nov 3 11:47:51.958: BGP: bgp_rwatch_notify: BGP_RWATCH_APPL_NHOP *Nov 3 11:47:51.958: EvD: charge penalty 500, new accum. penalty 500, flap count 12 *Nov 3 11:47:51.958: BGP: bgp_rwatch_notify: BGP_RWATCH_APPL_NBR *Nov 3 11:47:51.958: BGP: nbr global 7.7.7.7 bgp_process_bnbr_notification not reachable *Nov 3 11:47:51.958: BGP: bgp_rwatch_notify: BGP_RWATCH_APPL_NHOP *Nov 3 11:47:51.958: EvD: charge penalty 500, new accum. penalty 1000, flap count 13 *Nov 3 11:47:51.958: BGP: bgp_rwatch_notify: BGP_RWATCH_APPL_NBR *Nov 3 11:47:51.958: BGP: nbr global 7.7.7.7 bgp_process_bnbr_notification reachable *Nov 3 11:47:51.958: BGP: nbr global 7.7.7.7 Open active delayed 1024ms (0ms max, 60% jitter) *Nov 3 11:47:52.142: BGP: 7.7.7.7 active went from Idle to Active *Nov 3 11:47:52.142: BGP: 7.7.7.7 open active, local address 4.4.4.4 *Nov 3 11:47:52.143: BGP: ses global 7.7.7.7 (0xBBC7D948:0) act Adding topology IPv4 Unicast:base *Nov 3 11:47:52.143: BGP: ses global 7.7.7.7 (0xBBC7D948:0) act Send OPEN *Nov 3 11:47:52.143: BGP: ses global 7.7.7.7 (0xBBC7D948:0) act Building Enhanced Refresh capability *Nov 3 11:47:52.143: BGP: 7.7.7.7 active went from Active to OpenSent *Nov 3 11:47:52.143: BGP: 7.7.7.7 active sending OPEN, version 4, my as: 65019, holdtime 180 seconds, ID 4040404 *Nov 3 11:47:52.147: BGP: 7.7.7.7 active KEEPALIVE write request serviced in BGP_IO *Nov 3 11:47:52.147: BGP: 7.7.7.7 active service 2 read request in BGP_IO *Nov 3 11:47:52.148: BGP: 7.7.7.7 active KEEPALIVE write request serviced in BGP_IO *Nov 3 11:47:52.148: BGP: 7.7.7.7 active service 2 read request in BGP_IO *Nov 3 11:47:52.148: BGP: 7.7.7.7 active service 2 read request in BGP_IO *Nov 3 11:47:52.148: BGP: 7.7.7.7 active rcv message type 1, length (excl. header) 38 *Nov 3 11:47:52.148: BGP: ses global 7.7.7.7 (0xBBC7D948:0) act Receive OPEN *Nov 3 11:47:52.148: BGP: 7.7.7.7 active rcv OPEN, version 4, holdtime 180 seconds *Nov 3 11:47:52.148: BGP: 7.7.7.7 active rcv OPEN w/ OPTION parameter len: 28 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active rcvd OPEN w/ optional parameter type 2 (Capability) len 6 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active OPEN has CAPABILITY code: 1, length 4 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active OPEN has MP_EXT CAP for afi/safi: 1/1 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active rcvd OPEN w/ optional parameter type 2 (Capability) len 2 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active OPEN has CAPABILITY code: 128, length 0 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active OPEN has ROUTE-REFRESH capability(old) for all address-families *Nov 3 11:47:52.148: BGP: 7.7.7.7 active rcvd OPEN w/ optional parameter type 2 (Capability) len 2 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active OPEN has CAPABILITY code: 2, length 0 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active OPEN has ROUTE-REFRESH capability(new) for all address-families *Nov 3 11:47:52.148: BGP: 7.7.7.7 active rcvd OPEN w/ optional parameter type 2 (Capability) len 2 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active OPEN has CAPABILITY code: 70, length 0 *Nov 3 11:47:52.148: BGP: ses global 7.7.7.7 (0xBBC7D948:0) act Enhanced Refresh cap received in open message *Nov 3 11:47:52.148: BGP: 7.7.7.7 active rcvd OPEN w/ optional parameter type 2 (Capability) len 6 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active OPEN has CAPABILITY code: 65, length 4 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active OPEN has 4-byte ASN CAP for: 7 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active rcvd OPEN w/ remote AS 7, 4-byte remote AS 7 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active KEEPALIVE requested (rcv_open) *Nov 3 11:47:52.148: BGP: ses global 7.7.7.7 (0xBBC7D948:0) act service keepalive IO request. *Nov 3 11:47:52.148: BGP: 7.7.7.7 active went from OpenSent to OpenConfirm *Nov 3 11:47:52.148: BGP: 7.7.7.7 active received KEEPALIVE, length (excl. header) 0 *Nov 3 11:47:52.148: BGP: 7.7.7.7 active went from OpenConfirm to Established *Nov 3 11:47:52.148: BGP: ses global 7.7.7.7 (0xBBC7D948:1) act Assigned ID *Nov 3 11:47:52.148: BGP: ses global 7.7.7.7 (0xBBC7D948:1) Up *Nov 3 11:47:52.148: BGP: nopeerup-delay post-boot, set to default, 60s *Nov 3 11:47:52.148: %BGP-5-ADJCHANGE: neighbor 7.7.7.7 Up R4# *Nov 3 11:47:52.148: BGP: 7.7.7.7 KEEPALIVE write request serviced in BGP_IO *Nov 3 11:47:52.148: BGP: 7.7.7.7 service 1 read request in BGP_IO *Nov 3 11:47:52.150: BGP: 7.7.7.7 KEEPALIVE requested (bgp_tx_converged) *Nov 3 11:47:52.150: BGP: ses global 7.7.7.7 (0xBBC7D948:1) service keepalive IO request. *Nov 3 11:47:52.150: BGP: 7.7.7.7 KEEPALIVE write request serviced in BGP_IO *Nov 3 11:47:52.150: BGP: 7.7.7.7 received KEEPALIVE, length (excl. header) 0 R4# *Nov 3 11:47:56.965: BGP_Router: unhandled major event code 128, minor 0 *Nov 3 11:47:56.965: BGP: bgp_rwatch_notify: BGP_RWATCH_APPL_NHOP *Nov 3 11:47:56.965: EvD: charge penalty 500, new accum. penalty 1148, flap count 14 *Nov 3 11:47:56.965: BGP: bgp_rwatch_notify: BGP_RWATCH_APPL_NBR *Nov 3 11:47:56.965: BGP: nbr global 7.7.7.7 bgp_process_bnbr_notification reachable R4# *Nov 3 11:48:01.727: BGP: Regular scanner timer event *Nov 3 11:48:01.727: BGP: Performing BGP general scanning *Nov 3 11:48:01.727: BGP: topo global:IPv4 Unicast:base Scanning routing tables *Nov 3 11:48:01.727: BGP: tbl IPv4 Unicast:base Performing BGP Nexthop scanning for general scan *Nov 3 11:48:01.727: BGP(0): Future scanner version: 30, current scanner version: 29 *Nov 3 11:48:01.727: BGP: topo global:IPv4 Multicast:base Scanning routing tables *Nov 3 11:48:01.727: BGP: tbl IPv4 Multicast:base Performing BGP Nexthop scanning for general scan *Nov 3 11:48:01.727: BGP(6): Future scanner version: 31, current scanner version: 30 R4# *Nov 3 11:48:01.727: BGP: topo global:L2VPN E-VPN:base Scanning routing tables *Nov 3 11:48:01.727: BGP: tbl L2VPN E-VPN:base Performing BGP Nexthop scanning for general scan *Nov 3 11:48:01.727: BGP(10): Future scanner version: 31, current scanner version: 30 *Nov 3 11:48:01.727: BGP: topo global:MVPNv4 Unicast:base Scanning routing tables *Nov 3 11:48:01.727: BGP: tbl MVPNv4 Unicast:base Performing BGP Nexthop scanning for general scan *Nov 3 11:48:01.727: BGP(15): Future scanner version: 31, current scanner version: 30 R4#u all All possible debugging has been turned off
R4# *Nov 3 11:38:48.286: %BGP-3-NOTIFICATION: received from neighbor 7.7.7.7 4/0 (hold time expired) 0 bytes R4# *Nov 3 11:38:48.287: %BGP-5-NBR_RESET: Neighbor 7.7.7.7 reset (BGP Notification received) *Nov 3 11:38:48.287: %BGP-5-ADJCHANGE: neighbor 7.7.7.7 Down BGP Notification received *Nov 3 11:38:48.287: %BGP_SESSION-5-ADJCHANGE: neighbor 7.7.7.7 IPv4 Unicast topology base removed from session BGP Notification received *Nov 3 11:38:48.592: %BGP-5-ADJCHANGE: neighbor 7.7.7.7 Up R4# *Nov 3 11:38:53.305: %IPRT-3-RIB_LOOP: Resolution loop formed by routes in RIB R4# *Nov 3 11:41:49.500: %BGP-3-NOTIFICATION: received from neighbor 7.7.7.7 4/0 (hold time expired) 0 bytes R4# *Nov 3 11:41:49.500: %BGP-5-NBR_RESET: Neighbor 7.7.7.7 reset (BGP Notification received) *Nov 3 11:41:49.500: %BGP-5-ADJCHANGE: neighbor 7.7.7.7 Down BGP Notification received *Nov 3 11:41:49.500: %BGP_SESSION-5-ADJCHANGE: neighbor 7.7.7.7 IPv4 Unicast topology base removed from session BGP Notification received *Nov 3 11:41:49.798: %BGP-5-ADJCHANGE: neighbor 7.7.7.7 Up
Solved! Go to Solution.
11-03-2025 04:55 AM - edited 11-03-2025 04:57 AM
Hello @Road2CCIE
When you start adverse prefixes over your BGP peering, the route to the neighbor’s loopback becomes learned via BGP (or otherwise gets installed in the RIB pointing back through the neighbor), so the kernel’s route to reach the neighbor’s IP now points into BGP — creating a recursion/loop (see RIB_LOOP msg). BGP detects that the route to the neighbor is invalid (cannot resolve a next hop that is independent), so it tears down the session (“route to peer is invalid” msg).
To test in simpliest way add static route to peer loopback via physical neighbor IP... or use direct eBGP on the physical IPs, no loopbacks.
11-03-2025 04:55 AM - edited 11-03-2025 04:57 AM
Hello @Road2CCIE
When you start adverse prefixes over your BGP peering, the route to the neighbor’s loopback becomes learned via BGP (or otherwise gets installed in the RIB pointing back through the neighbor), so the kernel’s route to reach the neighbor’s IP now points into BGP — creating a recursion/loop (see RIB_LOOP msg). BGP detects that the route to the neighbor is invalid (cannot resolve a next hop that is independent), so it tears down the session (“route to peer is invalid” msg).
To test in simpliest way add static route to peer loopback via physical neighbor IP... or use direct eBGP on the physical IPs, no loopbacks.
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