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last change: November 14, 2019

Best Current Practices

In order to ensure maximum operational stability for all VIX participants, we kindly ask you to follow a few recommendations when configuring your VIX interface:

Filter your BGP announcements
Aggregate your routes
Filter your incoming BGP announcements
Announce your prefixes with site-specific communities
Turn off anything but IP on your interface

Below you will find some configuration examples for Cisco IOS. More detailed information on this topic and configuration examples for other systems and devices can be found at Euro-IX.


Filter your BGP announcements

Once you set up BGP, always filter your outgoing BGP announcements to other VIX participants. Not doing so will make your VIX connection useless and might even disturb other VIX participants.

Cisco example:

router bgp 12345
 neighbor VIX peer-group
 neighbor VIX version 4
 neighbor VIX activate
 neighbor VIX route-map to-VIX out

route-map to-VIX permit 10
 match as-path 40
 set community 1120:1

ip as-path access-list 40 permit ^$
ip as-path access-list 40 permit ^(_23456)+$
ip as-path access-list 40 permit ^(_34567)+$

Aggregate your routes

Do not announce every single IP range in your network. Rather try to aggregate your routes to whole prefixes. This keeps the routing tables of your routes small.

Cisco example:

router bgp 12345
 network 123.4.0.0 mask 255.254.0.0
 network 234.56.76.0 mask 255.255.252.0

Filter your incoming BGP announcements

The BGP announcements from your peers at the VIX shall also be filtered on your routing device. You can do this manually by checking the announced routes from your neighbors and statically configuring filters. On the other hand the IRR-Toolset can help you by automatically building filters for your devices. To keep your configuration small and tidy we recommend to make use of the maximum-prefix option in BGP.

Cisco example:

! maximum prefix filter for "big" neighbors
neighbor 1.2.3.4 maximum-prefix 20000 80 restart 60

! prefix-list for static filtering of routes
neighbor 2.3.4.5 prefix-list pl12345 in

! and the according prefix-list
ip prefix-list pl12345 seq 5 permit 1.2.0.0/16
ip prefix-list pl12345 seq 10 permit 1.3.4.0/24

Announce your prefixes with site-specific communities

To keep the cross-site traffic and the latency to your peers low we ask you to implement the site-specific BGP communities.


Turn off anything but IP on your interface

It is of no use if your device speaks any other protocols than IPv4 and IPv6 on the VIX interface. So please configure your interface not to broadcast any link-local protocols (except for ARP and IPv6 ND).

Unwelcome link-local protocols include, but are not limited to, the following:

  • IRDP
  • ICMP redirects
  • IEEE 802 Spanning Tree
  • Vendor proprietary protocols - these include, but are not limited to

    • Discovery protocols: CDP, EDP, FDP
    • VLAN/trunking protocols: VTP, DTP

  • Interior routing protocol broadcasts (e.g. OSPF, ISIS, IGRP, EIGRP)
  • BOOTP/DHCP
  • PIM-SM
  • PIM-DM
  • DVMRP
  • ICMPv6 ND-RA
  • UDLD
  • IP tracking
  • Layer2 keepalives

Cisco example:

! don't do redirects
no ip redirects

! don't do proxy ARP
no ip proxy-arp

! don't run CDP on your VIX interface
no cdp enable

! no directed broadcasts
no ip directed-broadcast

! v6 ND-RA is unnecessary and undesired
ipv6 nd suppress-ra

! disable DEC
no mop enable

! L2 keepalives are useless on VIX
no keepalive