1. Implementing Advanced Services Today – Routing & Multicast ken lindahl Chair, Internet2 Routing Working Group lindahl@ack.berkeley.edu Campus Focused Workshop on Advanced Networking San Diego, CA 4 December 2000

2. Campus Focused Workshop on Advanced Networking2 Routing

3. 4 December 2000 Campus Focused Workshop on Advanced Networking3 Routing Working Group  Chair: ken lindahl, UC Berkeley  current topics: Explicit Routing Internet2 Routing Registry (I2db) Internet2/Commodity Internet Routing Asymmetry  http://www.internet2.edu/routing/

4. 4 December 2000 Campus Focused Workshop on Advanced Networking4 Internet2 / Commodity Internet Routing Asymmetry  traffic between two Internet2 sites uses Abilene in one direction and commodity Internet in the other.  reduced performance: lower bandwidth, greater latency, greater jitter, higher packet loss  reported by Hank Nussbacher at Spring 2000 Members Meeting http://www.internet-2.org.il/i2-asymmetry/  very pronounced cases can be seen in the Abilene Connector mrtg graphs (Joe St Sauver) –http://monon.uits.iupui.edu/abilene/

5. 4 December 2000 Campus Focused Workshop on Advanced Networking5 Asymmetry example #1 Abilene Connector mrtg graphs  e.g. Georgetown (NYCM Connector) 11/30/2000 http://monon.uits.iupui.edu/abilene/nycm/georgetown-bits.html in / max in (to Abilene) out / max out (from Abilene)

6. 4 December 2000 Campus Focused Workshop on Advanced Networking6 Asymmetry example #2 Abilene Connector mrtg graphs  e.g. Cornell (NYCM Connector) 11/30/2000 http://monon.uits.iupui.edu/abilene/nycm/cornell-bits.html in / max in (to Abilene) out / max out (from Abilene)

7. 4 December 2000 Campus Focused Workshop on Advanced Networking7 Abilene Connector mrtg graphs Limitations  Abilene Connector mrtg graphs won’t show asymmetry in many cases, e.g.:  campus connects to a gigaPoP Abilene graphs will show aggregated statistics for all campuses connected to the gigaPoP, tending to hide asymmetry for a single campus. gigaPoP and campus graphs might reveal asymmetry. but, some gigaPoPs offer “shared” ISP; campuses may have a single link to gigaPoP for both Internet2 and commodity traffic. campus mrtg graphs won’t reveal asymmetry in this case.

8. 4 December 2000 Campus Focused Workshop on Advanced Networking8 Abilene Connector mrtg graphs Limitations  Abilene Connector mrtg graphs won’t show asymmetry in many cases, e.g.:  parts of the campus network are routed asymmetrically incorrect BGP configuration prevents some campus prefixes from being announced some campus subnets don’t reach Internet2 connection; instead, follow campus default to commodity Internet.

9. 4 December 2000 Campus Focused Workshop on Advanced Networking9 Asymmetry example #3 Asymmetry of Internet-2, slide 17 source: The Asymmetry of Internet2, Hank Nussbacher, March 2000, http://www.internet-2.org.il/i2-asymmetry/

10. 4 December 2000 Campus Focused Workshop on Advanced Networking10 Asymmetry example #4 Asymmetry of Internet-2, slide 18 –slide 18 from Hank’s talk source: The Asymmetry of Internet2, Hank Nussbacher, March 2000, http://www.internet-2.org.il/i2-asymmetry/

11. 4 December 2000 Campus Focused Workshop on Advanced Networking11 Asymmetry example #5 Asymmetry of Internet-2, slide 20 source: The Asymmetry of Internet2, Hank Nussbacher, March 2000, http://www.internet-2.org.il/i2-asymmetry/

12. 4 December 2000 Campus Focused Workshop on Advanced Networking12 Routing Asymmetry  estimated 30% of Internet2 exhibits this sort of asymmetry –The Asymmetry of Internet-2, Hank Nussbacher, March 2000  in some cases, campuses are aware of the issue; need to upgrade network equipment to fix.

13. 4 December 2000 Campus Focused Workshop on Advanced Networking13 Detecting Asymmetry source: The Asymmetry of Internet2, Hank Nussbacher, March 2000, http://www.internet-2.org.il/i2-asymmetry/ Detecting Asymmetry Nussbacher’s Looking Glass test

14. 4 December 2000 Campus Focused Workshop on Advanced Networking14 Detecting Asymmetry  campus Surveyor or NLANR AMP might be able to detect asymmetry http://www.advanced.org/surveyor/ http://amp.nlanr.net/ typically located near the campus Internet2 link, so might not detect asymmetries affecting interior subnets.  traceroute to Internet2 sites from interior subnets will reveal instances where outbound data is via the commodity Internet. time-intensive. not available to network engineers at other sites.

15. 4 December 2000 Campus Focused Workshop on Advanced Networking15 Detecting Asymmetry  Abilene Core Node Router Proxy can be used to check campus BGP announcements doesn’t really show that data will be delivered correctly … but if the BGP announcements are incorrect, packets are unlikely to take the desired path.  Summary: several incomplete and/or inadequate tools exist. Routing WG will investigate this issue and try to find a solution. participants will be welcomed! to join, see http://www.internet2.edu/routing/

16. 4 December 2000 Campus Focused Workshop on Advanced Networking16 Interior routing  what’s to say?  encourage use of link-state IGP, e.g. OSPF, EIGRP (cisco proprietary).  generally, not necessary to redistribute external routes into IGP; instead use default to deliver packets to border router, let BGP do the work from there.  most importantly, make sure the packets are following intended paths.

17. 4 December 2000 Campus Focused Workshop on Advanced Networking17 port duplex mis-matches  not routing, per se…  some think this is the most commonly seen performance killer in the Internet today.  often is the result of autonegotiation failure between connected devices.  YMMV, consider disabling autonegotiation; rely on manually configured speed and duplex... … especially on switch-to-switch and switch-to-router links (how often do these change speed or duplex?)

18. 4 December 2000 Campus Focused Workshop on Advanced Networking18 Multicast

19. 4 December 2000 Campus Focused Workshop on Advanced Networking19 Multicast Working Group  Chair: Kevin Almeroth, UC Santa Barbara  currently focused on encouraging campus deployment of IP multicast  http://www.internet2.edu/multicast/ disclaimer: content of this presentation should be blamed on ken, not Kevin.

20. 4 December 2000 Campus Focused Workshop on Advanced Networking20 Internet2 Multicast Architecture  PIM Sparse-Mode avoids periodic flooding of all multicast groups; important for high-bandwidth Internet2 multicast applications.  MBGP on border routers allows non-congruent unicast and multicast topologies; important when a site does not use it’s ISP for multicast.  MSDP between neighboring ASs communicate Sender Active information to RPs in all external PIM domains.  for details, see NCNE Multicast page; http://www.ncne.org/faq/multicast.html

21. 4 December 2000 Campus Focused Workshop on Advanced Networking21 PIM issues  version: should be PIMv2 vendor interoperability (e.g. Nortel: PIMv2 SM only) cisco: requires IOS 12.0 or later  auto-RP vs. BootStrap Router (BSR) auto-RP is cisco-proprietary; supports cisco’s v1/v2 interoperability mode; requires Sparse-Dense-Mode (interior interfaces only); works with administratively scoped zones BSR is part of PIMv2 spec, supports vendor interoperability; may not work with administratively scoped zones (still true?)

22. 4 December 2000 Campus Focused Workshop on Advanced Networking22 Monitoring Multicast  NLANR Beacon loss one-way delay jitter out-of-order arrivals duplication

23. 4 December 2000 Campus Focused Workshop on Advanced Networking23 Monitoring Multicast  NLANR Beacon documentation and source (java), available at http://dast.nlanr.net/Projects/Beacon/  Abilene Beacon page http//palpatine.ucs.indiana.edu:9999/ only two sites currently; not ready for prime-time?  suggestion: deploy Beacons around campus to monitor campus multicast; also one at/near border to peer with GigaPoP and other campuses.

24. 4 December 2000 Campus Focused Workshop on Advanced Networking24 Monitoring Multicast  Abilene multicast tools Multicast Route Viewer, MSDP logger, SDR Monitor http://www.abilene.iu.edu/index.cgi?page=multicast  SDR Monitor at UCSB http://steamboat.cs.ucsb.edu/sdr-monitor/ shows whether SDR announcements from your campus are getting out also, gives an idea of what SDR announcements your campus should be able see  list of multicast monitoring and debugging tools http://www.ncne.nlanr.net/faq/mcast_eng_faq.html#42

25. 4 December 2000 Campus Focused Workshop on Advanced Networking25 Multicast bandwidth control using rate-limiting  cisco routers support configurable rate-limits on interfaces ip multicast rate-limit out 4000 ip multicast rate-limit in 4000 limits total {in,out}bound multicast to 4Mbps  when configured limit is exceeded, multicast packets are dropped indiscriminately some multicast is pretty important and should not be dropped: OSPF, PIM messages, NTP can use access-lists to exempt well-known groups from rate-limiting

26. 4 December 2000 Campus Focused Workshop on Advanced Networking26 Multicast bandwidth control using administratively scoped zones  parts of the campus network that are not able to handle high-bandwidth multicast (e.g. >10Mbps) need protection  if the sender is on your campus and you can influence the group address that is used, administratively scoped multicast boundaries can keep users in bandwidth- challenged parts of the network from joining high-bandwidth sessions.  but you probably can’t control sessions that originate from outside your campus.  configuration can be complicated, involving multiple RPs and multiple RP mapping agents, each carefully scoped. c.f. Developing IP Multicast Networks, Beau Williamson, Cisco Press

27. 4 December 2000 Campus Focused Workshop on Advanced Networking27 Constraining multicast flooding – IGMP Snooping vs CGMP  IGMP Snooping switch inspects IGMP membership reports from hosts to determine which ports a group should be forwarded out can be CPU intensive (switch must inspect all multicast packets). implementations appear to differ among vendors.  CGMP switch forwards IGMP membership reports to router; router uses CGMP to tell the switch which ports a group should be forwarded out moves CPU load to the router (minimal) cisco proprietary

28. 4 December 2000 Campus Focused Workshop on Advanced Networking28 Constraining multicast flooding – IGMP Snooping vs CGMP  use one or the other on switched LANs that have connected hosts  Issue: leave latency IGMPv1 hosts do not send IGMP Leave Group messages, so forwarding state on switch must time out. (Affects both IGMP snooping and CGMP).  Issue: does not work on router ports routers don’t send host membership reports, so neither IGMP snooping nor CGMP works on router ports. Don’t use either on a backbone switch with only routers attached.

29. 4 December 2000 Campus Focused Workshop on Advanced Networking29 the next thing: SSM  Source-Specific Multicast addresses scalability issue of earlier forms of multicast receivers specify desired source when joining group source and group information learned via non-multicast means (e.g. web page)  requires IGMPv3 for (S,G) joins some host implementations are available requires support in last-hop router (cisco EFT images now, supported releases soon) cisco offers 2 interim workarounds: IGMPv3lite and URD (URL Rendezvous Directory)

30. 4 December 2000 Campus Focused Workshop on Advanced Networking30 the next thing: SSM  cisco information http://www.cisco.com/univercd/cc/td/doc/product/software/io s121/121newft/121t/121t3/dtssm.htm  U of Oregon SSM trial http://videolab.uoregon.edu/projects.html  IETF WG http://www.ietf.org/html.charters/ssm-charter.html