Current Consultations

May 2020: Consultation on removal of the multicast LAN

LINX is obliged to provide a multicast LAN as per the MoU. Currently the multicast LAN only has two connected ports and we have seen no sign of traffic increasing on this LAN . Most if not all other IXPs do not provide a separate LAN for multicast, and with the deployment of EVPN on LON2 and later on LON1, the need for separation of multicast traffic has diminished. With only two connected ports and low traffic levels the need to maintain a separate LAN for multicast traffic has seemingly diminished. We would therefore like to consult on changes to remove the separate multicast LAN, by making the following changes to the MoU:

  1. Allow all multicast traffic on the normal peering LAN.
  2. Only allow IPv6 multicast on the peering LAN in an effort to encourage adoption.
Current MoU
Proposed MoU
 2.3  Frames forwarded to a member interface which is part of the LINX peering LAN(s) shall not be addressed to a multicast or broadcast MAC destination address except as follows:

broadcast ARP packets
multicast IPv6 Neighbour Solicitation packets

where a member interface is a member of the LINX multicast VLAN, in which case frames may be forwarded which are destined to multicast group addresses

2.3  Frames forwarded to a member interface which is part of the LINX peering LAN(s) shall not be addressed to a broadcast MAC destination address except as follows:

broadcast ARP packets

2.4  Traffic for link-local protocols shall not be forwarded to member interfaces which are part of the LINX peering LAN(s) except for the following:

ARP
IPv6 Neighbour solicitations and advertisements
where a member interface is a member of the LINX multicast VLAN, in which case PIM-SM and MSDP may be run on the interface

Link local protocols includes but is not limited to:
IRDP
ICMP redirects
IEEE802 Spanning Tree
Vendor proprietary discovery protocols (e.g. CDP, EDP)
Interior routing protocol broadcasts (e.g. OSPF, ISIS, IGRP, EIGRP)
BOOTP/DHCP
PIM-SM
PIM-DM
DVMRP

2.4  Traffic for link-local protocols shall not be forwarded to member interfaces which are part of the LINX peering LAN(s) except for the following:

ARP
IPv6 Neighbour solicitations and advertisements
PIM-SM
MSDP

Link local protocols includes but is not limited to:
IRDP
ICMP redirects
IEEE802 Spanning Tree
Vendor proprietary discovery protocols (e.g. CDP, EDP)
Interior routing protocol broadcasts (e.g. OSPF, ISIS, IGRP, EIGRP)
BOOTP/DHCP
PIM-DM
DVMRP

4.1  All exchange of routes across the LINX network shall be via BGP4, except where a member interface is a member of the LINX multicast VLAN, in which case PIM-SM and MSDP may also be run on that interface.4.1  All exchange of routes across the LINX network shall be via BGP4, or where a member interface is used to exchange multicast traffic, in which case PIM-SM and MSDP may also be run on that interface.

Next Steps

We would like to solicit feedback on the above with the target of presenting this as a formal resolution at a general meeting held at LINX110 in November 2020. The Board will consider amending the proposal taking into account any comments received.

If any LINX member wishes to comment on these changes, please contact the LINX member relations team.