Transit and IX problem

RouterOS Forwarding Protocols
1

my router CCR1072 i want help bgp to mikrotik we now have 1G cogent transit and 10G netix internet exchange.

The problem is that the traffic going through the constant cogent is not going to go one way from the other.

I would like you to help me.

2

Hello BGDS,

If I understand your question correctly, your router is routing all your traffic out via Cogent and not using the NetIX connection?

Based on the Hurricane Electric BGP Lookup (https://bgp.he.net/AS209702), you currently have a BGP peering session with both NetIX and Cogent. There are a few questions:

  • Are you taking a full table from Cogent and exporting your RIPE-assigned prefixes to both Cogent and NetIX?
  • How have you configured your export and import route filters?

It sounds like your filters aren’t configured correctly. Do you have a looking glass configured that I can use to take a look at the routes being sent and received? If you want some hands-on help configuring your router, feel free to send me a private message.

3

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4

Best guess is you are importing routes from both, but because your cogent routers are older they are preferred (i.e. that bgp session came up first). I would set a BGP Local Pref on the IX routes only.

If this is for inbound traffic only going via cogent, then make sure you are advertising your ranges right to the IX, use their looking glass if they have one. Another suggestion is to advertise smaller prefixes to the IX (so if you had a /22, advertise /22 to cogent but 2x /23’s to IX) to ensure those listening on the IX prefer your IX routes more.

5

Also ensure your Cogent and IX peers are associated with the same BGP instance, multiple instances are when you need totally separate BGP for isolated VRFs.

6

This would have to be one of the worst ways to “force” carriers to prefer a certain route. There are other ways to achieve what they are looking for.

7

What are the better ways to influence the incoming traffic?

I have been having this exact same issue since upgrading to v7..

Very little incoming traffic uses the IX, only transit is used.. I think outgoing is fixed now, v7.12 may have “fixed” a few of my outgoing traffic frustrations…?

Full routing table from transit.

Transit out rule, pretty sure this shouldn’t be here, should just be on the In rule(?), but I have tried a LOT of things..

if (dst in 192.0.2.0/24 && dst-len == 24) { set bgp-local-pref 50; accept; }

IX out rule, same as above..

if (dst in 192.0.2.0/24 && dst-len == 24) {set bgp-local-pref 150; accept; }

My bottom transit-in rule, rules above this one are for rejecting bogons
set bgp-local-pref 50; set pref-src 192.0.2.1; accept;

My bottom IX rule, same as above

set bgp-local-pref 150; set pref-src 192.0.2.1; accept;

I also tried distance instead of bgp-local-pref, the distance value changes in the /ip/route output but it still didn’t use the lower distance before.

To use archive.org,

 /ip/route> print where 207.241.224.2 in dst-address
Flags: D - DYNAMIC; A - ACTIVE; s - STATIC, b - BGP
Columns: DST-ADDRESS, GATEWAY, DISTANCE
#     DST-ADDRESS       GATEWAY       DISTANCE
0  As 0.0.0.0/0         198.51.100.193       254
  DAb 207.241.224.0/20  203.0.113.9        20
  D b 207.241.224.0/20  203.0.113.9        20
  D b 207.241.224.0/20  198.51.100.193        20

So, of the “other ways” which are the best?

AS-Path is my first thought, MED a close second.