BGP ECMP is not working in my scenario

General questions
,
1

Hi Team,

I am trying to setup BGP ECMP in my test scenario before implementing it in production scenario. I really failed to understand why ECMP is not being setup in my scenario? Can someone pls help? Here is my scenario and config

ECMP
ECMP1280×720 72.9 KB

R1 Config

set interfaces ethernet eth0 address '10.10.20.10/24'
set interfaces ethernet eth0 hw-id '00:0c:29:d4:6e:9e'
set interfaces ethernet eth1 address '10.10.30.10/24'
set interfaces ethernet eth1 hw-id '00:0c:29:d4:6e:a8'
set interfaces ethernet eth2 address '10.10.40.10/24'
set interfaces ethernet eth2 hw-id '00:0c:29:d4:6e:b2'
set interfaces ethernet eth3 address '10.44.44.10/24'
set interfaces ethernet eth3 hw-id '00:0c:29:d4:6e:bc'
set interfaces loopback lo
set policy route-map AS65004 rule 10 action 'permit'
set policy route-map AS65004 rule 10 set as-path-prepend '65004'
set protocols bgp 65001 address-family ipv4-unicast maximum-paths ebgp '3'
set protocols bgp 65001 address-family ipv4-unicast network 10.44.44.0/24
set protocols bgp 65001 neighbor 10.10.20.20 remote-as '65002'
set protocols bgp 65001 neighbor 10.10.20.20 update-source '10.10.20.10'
set protocols bgp 65001 neighbor 10.10.30.20 remote-as '65003'
set protocols bgp 65001 neighbor 10.10.30.20 update-source '10.10.30.10'
set protocols bgp 65001 neighbor 10.10.40.20 remote-as '65005'
set protocols bgp 65001 neighbor 10.10.40.20 update-source '10.10.40.10'

R2 Config

set interfaces ethernet eth0 address '10.10.20.20/24'
set interfaces ethernet eth0 hw-id '00:0c:29:1a:64:0f'
set interfaces ethernet eth1 address '192.168.20.20/24'
set interfaces ethernet eth1 hw-id '00:0c:29:1a:64:19'
set interfaces loopback lo
set protocols bgp 65002 neighbor 10.10.20.10 remote-as '65001'
set protocols bgp 65002 neighbor 10.10.20.10 update-source '10.10.20.20'
set protocols bgp 65002 neighbor 192.168.20.10 remote-as '65004'
set protocols bgp 65002 neighbor 192.168.20.10 update-source '192.168.20.20'

R3 Config

set interfaces ethernet eth0 address '10.10.30.20/24'
set interfaces ethernet eth0 hw-id '00:0c:29:b5:16:c7'
set interfaces ethernet eth1 address '192.168.30.20/24'
set interfaces ethernet eth1 hw-id '00:0c:29:b5:16:d1'
set interfaces loopback lo
set protocols bgp 65003 neighbor 10.10.30.10 remote-as '65001'
set protocols bgp 65003 neighbor 10.10.30.10 update-source '10.10.30.20'
set protocols bgp 65003 neighbor 192.168.30.10 remote-as '65004'
set protocols bgp 65003 neighbor 192.168.30.10 update-source '192.168.30.20'

R4 config

set interfaces ethernet eth0 address '10.10.40.20/24'
set interfaces ethernet eth0 hw-id '00:0c:29:ef:bb:2c'
set interfaces ethernet eth1 address '192.168.40.20/24'
set interfaces ethernet eth1 hw-id '00:0c:29:ef:bb:36'
set interfaces loopback lo
set protocols bgp 65005 neighbor 10.10.40.10 remote-as '65001'
set protocols bgp 65005 neighbor 10.10.40.10 update-source '10.10.40.20'
set protocols bgp 65005 neighbor 192.168.40.10 remote-as '65004'
set protocols bgp 65005 neighbor 192.168.40.10 update-source '192.168.40.20'

R5 Config

set interfaces ethernet eth0 address '192.168.20.10/24'
set interfaces ethernet eth0 hw-id '00:0c:29:e3:b7:c7'
set interfaces ethernet eth1 address '192.168.30.10/24'
set interfaces ethernet eth1 hw-id '00:0c:29:e3:b7:d1'
set interfaces ethernet eth2 address '192.168.40.10/24'
set interfaces ethernet eth2 hw-id '00:0c:29:e3:b7:db'
set interfaces ethernet eth3 address '172.28.7.10/24'
set interfaces ethernet eth3 hw-id '00:0c:29:e3:b7:e5'
set interfaces loopback lo
set policy route-map AS65001 rule 10 action 'permit'
set policy route-map AS65001 rule 10 set as-path-prepend '65001'
set protocols bgp 65004 address-family ipv4-unicast maximum-paths ebgp '3'
set protocols bgp 65004 address-family ipv4-unicast network 172.28.7.0/24
set protocols bgp 65004 neighbor 192.168.20.20 remote-as '65002'
set protocols bgp 65004 neighbor 192.168.20.20 update-source '192.168.20.10'
set protocols bgp 65004 neighbor 192.168.30.20 remote-as '65003'
set protocols bgp 65004 neighbor 192.168.30.20 update-source '192.168.30.10'
set protocols bgp 65004 neighbor 192.168.40.20 remote-as '65005'
set protocols bgp 65004 neighbor 192.168.40.20 update-source '192.168.40.10'

R1 Routing Table


   vyos@R1# run show ip bgp
BGP table version is 3, local router ID is 10.44.44.10, vrf id 0
Default local pref 100, local AS 65001
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
*> 10.44.44.0/24    0.0.0.0                  0         32768 i
*  172.28.7.0/24    10.10.40.20                            0 65005 65004 i
*                   10.10.30.20                            0 65003 65004 i
*>                  10.10.20.20                            0 65002 65004 i

R5 Routing Table

vyos@R5# run show ip bgp
BGP table version is 2, local router ID is 192.168.40.10, vrf id 0
Default local pref 100, local AS 65004
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
*  10.44.44.0/24    192.168.40.20                          0 65005 65001 i
*>                  192.168.20.20                          0 65002 65001 i
*                   192.168.30.20                          0 65003 65001 i
*> 172.28.7.0/24    0.0.0.0                  0         32768 i

**********************
vyos@R5# run show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
       T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
       F - PBR, f - OpenFabric,
       > - selected route, * - FIB route, q - queued, r - rejected, b - backup

B>* 10.44.44.0/24 [20/0] via 192.168.20.20, eth0, weight 1, 02:21:41
C>* 172.28.7.0/24 is directly connected, eth3, 02:39:34
C>* 192.168.20.0/24 is directly connected, eth0, 02:34:18
C>* 192.168.30.0/24 is directly connected, eth1, 02:39:35
C>* 192.168.40.0/24 is directly connected, eth2, 02:39:34
2

Hi,

BGP route selection algorithm states:

Multi-path checkIf multi-pathing is enabled, then check whether the routes not yet distinguished in preference may be considered equal. If bgp bestpath as-path multipath-relax is set, all such routes are considered equal, otherwise routes received via iBGP with identical AS_PATHs or routes received from eBGP neighbours in the same AS are considered equal.

You should specify set protocols bgp ASN parameters bestpath as-path multipath-relax

1 Like
3

I guess I now started seeing Muti-path

On R1
set protocols bgp 65001 parameters bestpath as-path multipath-relax

On R5

set protocols bgp 65004 parameters bestpath as-path multipath-relax

However still on R1 and R5 I see best path selected

vyos@R5# run show ip bgp
BGP table version is 3, local router ID is 192.168.40.10, vrf id 0
Default local pref 100, local AS 65004
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
*= 10.44.44.0/24    192.168.40.20                          0 65005 65001 i
*>                  192.168.20.20                          0 65002 65001 i
*=                  192.168.30.20                          0 65003 65001 i
*> 172.28.7.0/24    0.0.0.0                  0         32768 i

on R1

vyos@R1# run show ip bgp
BGP table version is 4, local router ID is 10.44.44.10, vrf id 0
Default local pref 100, local AS 65001
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
*> 10.44.44.0/24    0.0.0.0                  0         32768 i
*= 172.28.7.0/24    10.10.40.20                            0 65005 65004 i
*=                  10.10.30.20                            0 65003 65004 i
*>                  10.10.20.20                            0 65002 65004 i
4

But with below version:

vyos@R3# run show v
version  vpn      vrrp     
[edit]
vyos@R1# run show version 
Version:      VyOS 1.1.8
Description:  VyOS 1.1.8 (helium)
Copyright:    2017 VyOS maintainers and contributors
Built by:     maintainers@vyos.net
Built on:     Sat Nov 11 13:44:36 UTC 2017
Build ID:     1711111344-b483efc
System type:  x86 64-bit
Boot via:     image
Hypervisor:   VMware
HW model:     VMware Virtual Platform
HW S/N:       VMware-56 4d 77 01 7d 9b e3 84-8b 1f 5c a5 af d4 93 3c
HW UUID:      564D7701-7D9B-E384-8B1F-5CA5AFD4933C
Uptime:       10:18:22 up 44 min,  1 user,  load average: 0.00, 0.01, 0.02

[edit]
vyos@R1# 

vyos@R1# set protocols bgp 65005 parameters bestpath as-path 
Possible completions:
   confed       Compare AS-path lengths including confederation sets & sequences
   ignore       Ignore AS-path length in selecting a route

      
[edit]

we can't get the option: multipath-relax.
is it not support at this version?
5

1.1.8 is outdated and not sure - Instead why not upgrade to 1.3 which is more stable

6

Yes, when switch to 1.3. the muti-path can be shown at the routing table.
But, it’s seem like not take effect. when i curl from a client to another side, but only one of the interface can be get the packet, another is nothing.
S>* 0.0.0.0/0 [210/0] via 192.168.2.1, eth0, weight 1, 06:04:15
C>* 192.168.2.0/24 is directly connected, eth0, 06:04:15
C>* 192.168.5.0/24 is directly connected, eth1, 05:58:37
B>* 192.168.8.0/24 [20/0] via 192.168.10.2, eth2, weight 1, 04:30:33

  •                   via 192.168.12.2, eth3, weight 1, 04:30:33

C>* 192.168.10.0/24 is directly connected, eth2, 05:58:37
C>* 192.168.12.0/24 is directly connected, eth3, 05:58:37
root@AR1:~#

is that something i missed?

7

when with different client, the ECMP can be shown as normal.

8

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