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IP Multicast Peering. Karl Jeacle kj@eircom.net. Overview. Overview of multicast peering points What, where, who, how? Equipment & associated costs Protocol interaction (PIM/MSDP/MBGP) Multicast peering policies Operational best common practice. What is a peering point?.
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IP Multicast Peering Karl Jeacle kj@eircom.net
Overview • Overview of multicast peering points • What, where, who, how? • Equipment & associated costs • Protocol interaction (PIM/MSDP/MBGP) • Multicast peering policies • Operational best common practice IIR Multicast - London
What is a peering point? • Peering definition • “Peering is the arrangement of traffic exchange between Internet Service Providers, at public exchange points, with zero sum financial settlement” • Note: • Public exchange points, not private connection • Zero sum settlement, no transit charges • Multicast and unicast traffic exchanged IIR Multicast - London
DECIX – Frankfurt, Germany INXS – Munich, Germany AMSIX – Amsterdam, Netherlands NDIX – Enschede, Netherlands NETNOD – Stockholm, Sweden LINX – London, UK LoNAP – London, UK MaNAP – Manchester, UK XchangePoint - London, UK VIX – Vienna, Austria BNIX – Brussels, Belgium SFINX – Paris, France GIGAPIX – Lisbon, Portugal CATNIX – Barcelona, Spain SIX – Bratislava, Slovakia CIXP – Geneva, Switzerland European exchanges IIR Multicast - London
Future exchange trials • Most exchanges planning trials in 2003 • INEX – Dublin, Ireland • MIXITA – Milan, Italy • NIX – Oslo, Norway • SWISSIX - Zurich, Switzerland IIR Multicast - London
Who can join? • Varies across exchange points • Network criteria must be met • Typically ISPs only • Sometimes content providers • Rarely end-users • Depends on MoU and T&C IIR Multicast - London
Exchange equipment • Desire to isolate multicast traffic from existing “production” unicast traffic • Separate switch used • Dedicated connection to multicast switch port • LINX – Extreme Summit 48 • Separate VLAN on same switch • Dedicated connection to port in multicast VLAN • AMSIX – Foundry BigIron 8000 & 15000 IIR Multicast - London
Exchange equipment • Some exchanges do not require an additional network connection • e.g. FICIX, NETNOD, SIX • OK if point-to-point (e.g. ATM) • Concern if shared access (e.g. Ethernet) • Multicast traffic looks like broadcast traffic • Switch will send data out on all ports • Bearable if multicast only, unacceptable if unicast • PIM Snooping or equivalent required IIR Multicast - London
PIM Snooping • Hosts connected to a switch • IGMP snooping prevents unwanted traffic • Routers connected to a switch • PIM used instead of IGMP • Switches do not “see” PIM messages • Traffic will be flooded on all ports • Solution: • Enable “PIM snooping” on switches so they can restrict multicast traffic flows to interested parties IIR Multicast - London
RGMP • Cisco provide RGMP • RouterPort Group Management Protocol • Proprietary, but submitted as IETF draft • Message format resembles IGMP to allow easier upgrade of existing switches • Unlike PIM Snooping, all devices (i.e. switch and routers) must run RGMP IIR Multicast - London
Member costs • Present for unicast peering already • New router is unnecessary • Extra port on existing router sufficient • Additional rental for multicast port • Software upgrades may be required • Main cost • Staff competence development • Depends on commitment to multicast IIR Multicast - London
Steps involved • Peering agreements • Are multicast & unicast peers equivalent? • Is a (new) peering agreement necessary? • Session configuration • MBGP / MSDP / PIM-SM • RIPE database • No specific multicast route entries IIR Multicast - London
Protocols required • Protocols required for multicast peering • MBGP • Exchange unicast routes to multicast sources • MSDP • Exchange “Source Active” messages (SAs) • PIM-SM • Allows branches of multicast distribution tree to be built between peers across the exchange IIR Multicast - London
MBGP • Multiprotocol Border Gateway Protocol • Not “Multicast BGP” • Multiprotocol extensions allow IPv6 & MPLS VPNs • MBGP exchanges unicast prefixes of multicast hosts, it does not exchange group addresses! • MBGP multicast rationale • Incongruent routing between unicast & multicast • Force multicast traffic to take alternative path IIR Multicast - London
Incongruent routes IIR Multicast - London
MBGP Policies • Peering policy • Unicast peering has AS path & prefix filters • Re-use depending on administrative policy • Can re-announce other peers’ prefixes… …a sort of pseudo-transit for multicast • Always agree first with peers concerned! IIR Multicast - London
MSDP • Multicast Source Discovery Protocol • Connects PIM-SM domains • Allows multicast sources for a group to be known across different domains • Peers exchange multicast “Source Active” messages (MSDP SAs) • SAs carried to PIM Rendezvous Points IIR Multicast - London
PIM-SM • PIM Sparse Mode • Allow PIM neighbours to be established • Branches of multicast distribution tree are built between peers across the exchange • Enable on exchange-facing interface • Ideally run natively back to core of network • Or tunnel back to multicast-enabled network IIR Multicast - London
Best Common Practice • Keep local traffic local! • Filter traffic & SAs with ACLs • Private source addresses • Private group destination addresses • SSM 232/8 space • PIM BSR and/or Auto-RP • Misc services (e.g. discovery protocols) IIR Multicast - London
How active? • # Participants • Usually numerous interested members… • but typically just 10-20% get up & running • Traffic • Small percentage of unicast (~ 1%) • Efficiency – it’s multicast! • Lack of content IIR Multicast - London
Evangelism! • If you are an ISP • Investigate multicast peering options • Start work on enabling native multicast • If you are an ISP customer • Ask your provider for multicast service • Ask them for details on peering presence IIR Multicast - London
More information • Exchange points • http://www.ep.net/ • http://www.euro-ix.net/ispportal/ixpmatrix.htm • BCP ACLs • ftp://ftpeng.cisco.com/ipmulticast/config-notes/msdp-sa-filter.txt • Sample config • http://multicast.eircom.net/ IIR Multicast - London