Network Technical Specifications


Ports, IPv4 and IPv6

All ports on the LU-CIX public exchange infrastructure are Ethernet and are available at the following speeds:

  • 1 Gbps (GE) - 1000BASE-LX (only on special request)
  • 10 Gbps (10GE) - 10GBASE-LR
  • 100 Gbps (100GE) – 100GBASE-LR4 (100GBASE-LR1 on special request)

Additionally, LU-CIX is able to aggregate 10GE or 100GE ports to provide higher bandwidth trunks.

Members can peer with IPv4, IPv6 or both. LU-CIX strongly recommends peering with both IPv4 and IPv6 address families. IPv4 and IPv6 addresses on the LU-CIX peering VLAN and on the VoIP Exchange VLAN will be assigned by LU-CIX, one each per member port per VLAN.

IPv4 and IPv6 addresses on the Remote IX peering VLANs will be assigned by the remote IX, one each per member port per remote IX peering VLAN.


MAC Layer

Ethernet framing

The LU-CIX infrastructure is based on the Ethernet II (or “DIX Ethernet”) standard. This means that LLC/SNAP encapsulation (802.2) is not permitted.


Frames forwarded to LU-CIX ports must have one of the following Ether types:

  • 0x0800 - IPv4
  • 0x0806 - ARP
  • 0x86dd - IPv6

One MAC address per port

Frames forwarded to an individual LU-CIX port must all have the same source MAC address. LU-CIX enforces the single MAC address per port by using Port Security and MAC filtering. For security reasons, reception of a frame with any other source MAC address will trigger an automatic port shutdown.

Hardware changes also introduce a change of the source MAC address. To guarantee a smooth migration please contact LU-CIX support a few business days ahead of your change. During a short period of time we can accept two different source MAC addresses on a port.


Network layer

No proxy ARP

Use of proxy ARP on the router's interface to the Exchange is not allowed.

Unicast only

Frames forwarded to LU-CIX ports must not be addressed to a multicast or broadcast MAC destination address except as follows:

  • broadcast ARP packets
  • multicast ICMPv6 Neighbour Discovery packets. This DOES NOT include Router Discovery packets.

No link-local traffic

Traffic for link-local protocols shall not be forwarded to LU-CIX ports.
Link-local protocols include, but are not limited to, the following list:

  • IRDP
  • ICMP redirects
  • IEEE 802 Spanning Tree
  • Vendor proprietary protocols. These include, but are not limited to:
    - Discovery protocols: CDP, EDP - VLAN/trunking protocols: VTP, DTP
    Interior routing protocol broadcasts (e.g. OSPF, ISIS, IGRP, EIGRP)
  • PIM-SM
  • PIM-DM
  • ICMPv6 ND-RA
  • UDLD
  • L2 Keepalives

The following link-local protocols are exceptions and are allowed:

  • ARP
  • IPv6 ND

No directed broadcast

IP packets addressed to any LU-CIX or Remote IX VLAN’s directed broadcast address must be blocked by the member.


BFD (Bidirectional Forwarding Detection)

LU-CIX recommends configuring BFD as a failure detection mechanism on all BGP peering sessions, be it peer-to-peer or with the route servers.

BFD is a generic keepalive and failure detection protocol that runs over almost any communication media. It allows sub-second failure detection, if participating systems are fast enough. It is designed as a lightweight protocol that can run autonomously in the forwarding engine of network devices, independent of the control plane.

In our case, BFD can be configured as an additional failure detection mechanism for BGP. Each BGP session will be doubled by a dedicated BFD session that runs on UDP port 3784, on the same IPv4 or IPv6 addresses as the BGP session itself. When BFD detects the failure of a neighbour, it informs the BGP process which immediately triggers the withdrawal of the neighbour’s routes, shortcutting the overly generous BGP timeouts and enabling the immediate use of an alternate route.

On LU-CIX, we encourage members to use BFD on their peer-to-peer peering sessions. This allows for extremely fast failover in case of data path outages. In addition, our route servers are by default configured with BFD passive sessions, see this page for details.

The following are our current recommended timer values for BFD:

  • Min Rx interval     400ms
  • Min Tx interval     400ms
  • Idle TX interval    1000ms
  • Multiplier              3