bgp upload issue

rpengineering · Tue Jun 14, 2011 5:25 pm

Dear,
i've 2 bgp sessions with the same carrier
the 2 internet connections are two 100 Mbps on two different phisical ethernet interface.
in the two peers i've the same configuration (differs only on /30 of remote peer)

the download is perfectly balanced, but the upload goes only on one interface.

routing bgp peers
add address-families=ip comment="" default-originate=never disabled=no hold-time=3m \
in-filter="" instance=default multihop=no name=ITNet nexthop-choice=default out-filter=\
bgp-itnet-out remote-address=151.9.xxx.xxx remote-as=1267 route-reflect=no tcp-md5-key="" \
ttl=default
add address-families=ip comment="" default-originate=never disabled=no hold-time=3m \
in-filter="" instance=default multihop=no name=ITNet2 nexthop-choice=force-self \
out-filter=bgp-itnet2-out remote-address=151.9.xxx.xxx remote-as=1267 route-reflect=no \
tcp-md5-key="" ttl=default

Please Help me..

blake · Tue Jun 14, 2011 6:01 pm

Are you receiving the same routes from both external peers? Are they sending you a default route, partial table, full table, or full w/ default route?

Also, you may want to read this. http://wiki.mikrotik.com/wiki/Manual:IP ... .29_routes

rpengineering · Tue Jun 14, 2011 6:39 pm

Dear,
the external peers ( is the same with 2 link) give me the full routing table.

in the ip route i'have some of:

# DST-ADDRESS PREF-SRC GATEWAY DISTANCE
0 ADb 1.0.4.0/22 151.9.1xx.xxx r... 20
1 Db 1.0.4.0/22 151.9.2xx.xx re... 20
2 ADb 1.1.1.0/30 151.9.1xx.xxx r... 20
3 Db 1.1.1.0/30 151.9.2xx.xx re... 20
4 ADb 1.5.0.0/16 151.9.1xx.xxx r... 20
5 Db 1.5.0.0/16 151.9.2xx.xx re... 20
6 ADb 1.9.0.0/16 151.9.1xx.xxx r... 20
7 Db 1.9.0.0/16 151.9.2xx.xx re... 20
8 ADb 1.11.0.0/21 151.9.1xx.xxx r... 20
9 Db 1.11.0.0/21 151.9.2xx.xx re... 20

....

etc

peer 1 151.9.1xx.xxx upload / download works
peer 2 151.9.2xx.xx download works only

blake · Tue Jun 14, 2011 7:18 pm

Could you do a 'print detail' on some of those routes so we can see the BGP weight and metrics between the two links? Also please put the output into a [ code ] block. http://forum.mikrotik.com/viewtopic.php?f=13&t=45259

rpengineering · Tue Jun 14, 2011 8:12 pm

Dear,
heare the ip route print detail ..

 0 ADb  dst-address=1.0.4.0/22 gateway=151.9.1xx.xxx reachable ether2 distance=20 scope=40        
        target-scope=10 bgp-as-path="1267,174,7545,7545,7545,7545,7545,56203" bgp-origin=igp 
        bgp-communities=174:21001,174:22013,1267:130,1267:200 received-from=151.9.1xx.xxx 

 1  Db  dst-address=1.0.4.0/22 gateway=151.9.212.89 reachable ether1 distance=20 scope=40 
        target-scope=10 bgp-as-path="1267,174,7545,7545,7545,7545,7545,56203" bgp-origin=igp 
        bgp-communities=174:21001,174:22013,1267:130,1267:200 received-from=151.9.2xx.xx 

 2 ADb  dst-address=1.1.1.0/30 gateway=151.9.133.229 reachable ether2 distance=20 scope=40 
        target-scope=10 bgp-as-path="1267,8968" bgp-origin=incomplete 
        bgp-communities=1267:180,1267:200 received-from=151.9.1xx.xxx 

 3  Db  dst-address=1.1.1.0/30 gateway=151.9.212.89 reachable ether1 distance=20 scope=40 
        target-scope=10 bgp-as-path="1267,8968" bgp-origin=incomplete 
        bgp-communities=1267:180,1267:200 received-from=151.9.2xx.xx 

 4 ADb  dst-address=1.5.0.0/16 gateway=151.9.133.229 reachable ether2 distance=20 scope=40 
        target-scope=10 bgp-as-path="1267,6939,4725" bgp-origin=igp 
        bgp-communities=1267:168,1267:200 received-from=151.9.1xx.xxx 

 5  Db  dst-address=1.5.0.0/16 gateway=151.9.212.89 reachable ether1 distance=20 scope=40 
        target-scope=10 bgp-as-path="1267,6939,4725" bgp-origin=igp 
        bgp-communities=1267:168,1267:200 received-from=151.9.2xx.xx 

 6 ADb  dst-address=1.9.0.0/16 gateway=151.9.133.229 reachable ether2 distance=20 scope=40 
        target-scope=10 bgp-as-path="1267,4788" bgp-origin=igp 
        bgp-communities=1267:168,1267:200,4788:200,4788:210 received-from=151.9.1xx.xxx

Eising · Fri Jun 17, 2011 2:39 pm

There is no maximum-path option on mikrotik, meaning it is not possible to configure outbound load-balancing on multiple paths with BGP. BGP on RouterOS will only select one path. There is no workaround with BGP as far as I know.

mrz · Fri Jun 17, 2011 3:19 pm

It is possible to configure BGP in RouterOS to use multiple paths. Here you can find examples
http://wiki.mikrotik.com/wiki/Manual:BG ... interfaces

Eising · Fri Jun 17, 2011 3:37 pm

Yes, with multihop and some sort of IGP to do the ECMP. That's not the same.

rpengineering · Fri Jun 17, 2011 4:02 pm

what's the solution ??

tronity2k · Tue Jun 21, 2011 7:16 pm

If you would sumarize bandwidth, you can use link-agregation (LACP).

two sessions with same uplink is normaly used for redundancy with 2 routers and bgp-communities for adjust uplink local-preference.

You can select out-bond traffic (with bgp filters and play with preference, med, etc.) but you only try play with up-link communities, by example: one link for your continent or country routers, and other for rest.

Is not good practice but can deaggregate your allocation and public diferent address blocks by bgp sessions.

Is the same problem with 2 uplinks, but the problem is that all routes have same as-path, in bgp only one route is active.

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