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Configuring BGP

This section describes how to configure BGP in Trisul ISP.

I-BGP Route Receiver​

Configure Trisul as an I-BGP peer of your external gateway routers or your route reflectors. Trisul doesn't advertise or withdraw any routes. It is a passive route collector. This lets Trisul build a virtual RIB for each router, and Trisul combines the NetFlow data from the routers with this RIB.

Configuring Trisul as a BGP peer​

The BGP support is present in the trisul-geo package. Make sure the package is installed on the Probe. It installs two systemd services:

  • trisul-bgp.service : the BGP peering service
  • trisul-bgp-ramfs-mount.service : a service that prepares a special RAMFS partition to store the route database

trisul-bgp.service​

This service uses a config file /usr/local/etc/trisul-probe/trisul_piranha.conf This is the only file you have to edit to start the service.

Say your AS number is 64500. Set the same AS number in local_as in the configuration file. Then add the neighbors one after the other. A minimal example config:

note

The examples on this page use AS 64500, from the documentation range (RFC 5398). Use your own AS number.

..
local_as 64500

local_ip4 172.17.17.27  

bgp_router_id 172.17.17.27

neighbor  10.10.16.12 64500
..

The parameters are :

local_as
Your (ISPs) AS number. Important this is not an external ASN, because we are creating an I-BGP session.

local_ip4
IP Address of the Trisul-Probe

bgp_router_id
You can use the same value as local_ip4. An IP Address of the Trisul-Probe, this address will appear in BGP messages on the remote peers.

neighbor
IP Address of the BGP neighbor then a space and the AS Number

Starting and verifying​

After configuring the neighbor above, you can start the BGP services.

$ systemctl start trisul-bgp-ramfs-mount
$ systemctl start trisul-bgp

Verifying​

Log in as admin and go to Context: default → Admin Tasks → BGP Route Receiver.

The page shows the status of each peer.

NetFlow vs BGP Peer address​

After the peering is established, you may need to link the NetFlow exporter IP address to the BGP Peer Address. Follow these steps.

  • Log in and go to Netflow → Routers and Interfaces. Note down the router IP address. This is the NetFlow exporter IP address, say 10.17.17.20.
  • Go to the router database directory. Here you will find the BGP Peer Addresses. The directory is located in /usr/local/var/ramdisk. Say the BGP Peer address corresponding to the netflow exporter address 10.17.17.20 is 10.10.20.37, you will find a database here.
root@ATJHSD33:/usr/local/var/ramdisk# ls
10.10.20.37_routes.db.sqlite3
  • Link the BGP peer database to the NetFlow exporter database:
$ ln -sf 10.10.20.37_routes.db.sqlite3  10.17.17.20_routes.db.sqlite3

The softlinks should show as below

$ ls -l
total 3300
-rw-r--r-- 1 trisul trisul 3379200 Jan 31 16:10 10.10.20.37_routes.db.sqlite3  
lrwxrwxrwx 1 trisul trisul      32 Jan  6 16:03 10.17.17.20_routes.db.sqlite3-> 10.10.20.37_routes.db.sqlite3

Common errors​

  1. Make sure TCP port 179 is open on the Trisul Probe firewall-cmd --zone=public --add-port=179/tcp
  2. Check the neighbor line in the config file for stray spaces, tabs or special characters.
  3. Double check the softlinks
  4. Restart the probes

How to add a new IGW​

Adding an IGW takes two steps:

  1. Configure NetStream on the IGW to export to one of the two Probe VIPs.
  2. Optionally, configure the BGP route receiver on the Trisul Probes and BGP on the IGW.

Configure NetStream and BGP on IGW​

NetStream on the IGW

Enable NetStream on all interfaces on the IGW and export to one of the two Probe VIPs. A sample config:

ip netstream as-mode 32
ip netstream timeout active 1
ip netstream timeout inactive 15
ip netstream tcp-flag enable
ip netstream export version 9 origin-as bgp-nexthop
ip netstream export template timeout-rate 1
ip netstream sampler fix-packets 100 inbound
ip netstream sampler fix-packets 100 outbound
ip netstream export source 172.20.101.61
ip netstream export host 172.20.17.107 51111
ipv6 netstream timeout active 1
ipv6 netstream timeout inactive 15
ipv6 netstream export template timeout-rate 1
#interface GigabitEthernet1/1/1
ip netstream inbound
ip netstream sampler fix-packets 1000 inbound
ip netstream sampler fix-packets 1000 outbound
ipv6 netstream inbound
ip netstream statistics enable
ipv6 netstream statistics enable

Next configure BGP on the IGW to peer with the probe VIP.

bgp 64500
peer 172.20.17.107 as-number 64500

BGP on Trisul Probe​

Next, configure the BGP receiver on the Trisul Probe. Say you added an IGW with IP address a.b.c.d (the ip netstream export source address).

  1. Log in to all Probes.
  2. Open /usr/local/etc/trisul-probe/trisul_piranha.conf.
  3. Add the new IGW as a BGP peer at the end of the file:
# PUT ONE LINE PER IGW HERE 
# IF USING ROUTE REFLECTOR / ROUTE SERVER Put a single entry here.
neighbor a.b.c.d  64500
  1. Restart the BGP receiver:
systemctl restart trisul-bgp

Next steps​

Install the ISP apps and dashboards.

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