Transcript NANOG 44
LISP: Practice and Experience November 2008 LISP Implementation Team: Vince Fuller, Darrel Lewis, David Meyer, Dino Farinacci, Andrew Partan, John Zwiebel Agenda • • • • Currently Deployed Network Configuring LISP Troubleshooting LISP Q/A LISP: Practice & Experience NANOG 44 Slide 2 LISP+ALT Today LISP: Practice & Experience NANOG 44 Slide 3 Deployment Model • Currently deployed LISP network elements are 1RU PCs (“titanium”) running a LISP-capable version of NXOS – There are also IOS and Open Source implementations underway • Endpoint Identifier (EID) Assignment Strategy – The basic idea : Geographic (probably) – With “ALT-Aggregators” strategically placed within a geography • GRE tunnel topology – ALT routers have no LISP features • Debugging lisp from within ALT is problematic – ALT-Aggregators are typically “ALT-only” – Note the ALT doesn’t require GRE LISP: Practice & Experience NANOG 44 Slide 4 Address Families • You can also respond to a Map-Request for a v6 EID with a v4 locator (and vice versa) – Effectively 4to4over6 or 6to6over4 • We call this “mixed locators” • This allows you to, for example, connect sites deploying IPv6 EIDs over IPv4 locators without an intervening native IPv6 capable network • More on Interworking in a minute LISP: Practice & Experience NANOG 44 Slide 5 xTR Configuration • Enable ITR Functionality – ip lisp itr – ipv6 lisp itr • Use the ALT to resolve mappings – ip lisp alt-vrf lisp • Enable ETR Functionality – ip lisp etr – ipv6 lisp etr • Configure an EID-to-RLOC database entry – ip lisp database-mapping <EID-Prefix> <RLOC> priority <p> weight <w> LISP: Practice & Experience NANOG 44 Slide 6 Configuring Mixed Locators • An ETR will typically advertise its EID-prefix into ALT – Attracts Map-Requests to the authoritative ETR • If you want “Mixed Locators” – ipv6 lisp database-mapping 2610:00d0:1200::/48 128.223.156.134 priority 1 weight 100 – ipv6 lisp database-mapping 2610:00d0:1200::/48 2001:468:D01:9C:80DF:9C86 priority 2 weight 100 • And if you want the Map-Reply to come back over IPv4 – ipv6 lisp etr send-ip-map-reply LISP: Practice & Experience NANOG 44 Slide 7 LISP PTR Config ! ! Use the LISP VRF for the ALT ! ipv6 lisp alt-vrf lisp ip lisp alt-vrf lisp ! ! Enable the PTR ! ipv6 lisp proxy-itr 2001:0468:0d01:009C::80df:9c23 ip lisp proxy-itr 198.6.255.37 That’s really it. Try http://www.lisp4.net or http://www.lisp6.net LISP: Practice & Experience NANOG 44 Slide 8 Case Study 1 • Turning on LISP broke external connectivity – First xTR implementation used static cache maps – Configured the box, enabled LISP – Lost all external connectivity • Learned early on that determining whether an address is an EID or an RLOC is critical – ip lisp itr forward-on-cache-miss – When we implemented ALT we had a new way of making this determination • ip lisp itr forward-on-ALT-miss • Nice that we saw this early and got it out of the way LISP: Practice & Experience NANOG 44 Slide 9 Case Study 2 • Early code didn’t seem to be able to ping between sites – – – – – Early code couldn’t even ping Tested under, worked Tested over, worked Tested through, worked (unit testing) Tested from loopback to loopback, failed • Code needed to handle receive path decapsulation differently than forwarding path • We narrowed this down by a process of elimination, not through seeing any error messages – Receive path issues always seem to bite you LISP: Practice & Experience NANOG 44 Slide 10 Case Study 3 • Problem was when IPv6 EID pinged IPv6 EID over a mixed locator RLOC – Dual stack ALT, this is a critical • MAP Reply was generated in IPv6 format – But the sending site was IPv4 only – Fix had ETR specify the address family to prefer to send replies in (assume IPv4) • This issue wasn’t unique to LISP either – Just because a host (or a site) supports an address family doesn’t mean there is an end to end path using it – As AAAA/A records have shown us LISP: Practice & Experience NANOG 44 Slide 11 Lessons Learned • ALT is simple to configure and operate – Set it and forget it! • Developing a debugging methodology is critical • For web based applications at least, stretch and first packet loss are overrated – Moved from data-probes to map-requests • You need tools (LISP traceroute) • Cache optimization on ITRs is important • Benefit of Separation… LISP: Practice & Experience NANOG 44 Slide 12 Open Questions • Who runs the mapping system, and what are their business models? • Can LISP be used for the IPv6 transition? • Effects of the mapping system on applications • PMTU effects • Caching behavior in xTRs • Enhancing locator reachability detection • How can we make xTRs even easier to operate? LISP: Practice & Experience NANOG 44 Slide 13 Questions/Comments? Contact us: [email protected] Information: http://www.lisp4.net http://www.lisp6.net OpenLISP: http://inl.info.ucl.ac.be/softwares/openlisp Thanks! LISP: Practice & Experience NANOG 44 Slide 14