IPv4/v6 Considerations Ralph Droms Cisco Systems

Transcription

1 Title IPv4/v6 Considerations Ralph Droms Cisco Systems

2 Agenda Motivation for IPv6 Review of IPv6 Impact of differences Tools and techniques

3 Why IPv6? More addresses More addresses More addresses Security, QoS, higher performance

4 IPv6 Opportunities DoD Memorandum of June 9, 2003 on Global Information Grid (GiG) policy: As of October 1, 2003, all GiG assets being developed, procured or acquired shall be IPv6 capable Rapidly expanding markets: AsiaPac Expanding technology markets: Mobile Wireless, WiFi hotspots Gaming Microsoft to deploy IPv6 with Windows

5 An observation From 50,000 feet, everything looks the same at ground level, everything is different.

6 Review of IPv6 and comparison to IPv4 Address size: IPv6 addresses are 128 bits Header format: entirely different Extension headers: Additional information stored in optional extension headers, followed by data Support for audio and video: flow labels and type of service allow audio and video applications to establish appropriate connections Extensible: new features can be added more easily Security: IPsec required No checksumming in IPv6, no fragmentation by routers

7 IPv6 base header Contains less information than IPv4 header TRAFFIC CLASS for service differentiation NEXT HEADER points to first extension header FLOW LABEL used to associate datagrams belonging to a flow or communication between two applications Routers use FLOW LABEL to forward datagrams along prearranged path

8 IPv6 Base Header Format Version Traffic Class Flow Label Payload Length Next Header Hop Limit Source Address Destination Address

9 Extension Headers Extension headers can be added between IP header and payload Usually transport protocol header: IPv6 base header TCP header TCP segment Next header = TCP

10 IPv6 Addressing 128-bit addresses, composed of network prefix and host suffix (64 bits each) No address classes - prefix/suffix boundary can fall anywhere Special types of addresses: unicast: single destination computer multicast: multiple destinations; possibly not at same site anycast: set of computers with same address; datagram is delivered to one computer from set Scoped addresses link-local addresses: only valid on link; never forwarded by router global addresses

11 IPv6 Address Notation 128-bit addresses unwieldy in dotted decimal; requires 16 numbers Groups of 16-bit numbers in hex separated by colons - colon hexadecimal (or colon hex) 69DC:8864:FFFF:FFFF:0:1280:8C0A:FFFF Zero-compression - series of zeroes indicated by two colons FF0C:0:0:0:0:0:0:B1 equivalent to FF0C::B1

12 Prefix and Router Advertisement Router sends router advertisement Router can act as default router List of prefixes assigned to link Each prefix has a preferred lifetime and a valid lifetime New prefixes can be announced at any time Hosts stop using expired prefixes Used for renumbering

13 Addresses and Interface IDs Host constructs addresses from advertised prefixes and interface ID Lowest-order 64-bit field of unicast address may be assigned in several different ways: auto-configured from a 64-bit EUI-64, or expanded from a 48- bit MAC address (e.g., Ethernet address) auto-generated pseudo-random number (to address privacy concerns) assigned via DHCP manually configured

14 Summary Comparison Addressing IP Service Address assignment IPv4 Solution 32 bit addresses, NAT DHCP IPv6 Solution 128 bit addresses, scoping Address autoconfiguration Security Mobility Quality of Service IP Multicast IPsec optional Mobile IP Differentiated service, integrated service IGMP/PIM/Multicast BGP IPsec mandated Mobile IP with direct routing Differentiated service, integrated service MLD/PIM/Multicast BGP,Scope Identifier

15 Issues in managing IPv6 nets and devices Stateless address autoconfiguration Device registration DNS and DNS updates Use of DNS in interfaces Multiple addresses on an interface Link-local and global addressing Device identification Multiple prefixes on a link Renumbering IPv6 addresses in MIBs

16 Devices addressing and management Devices may use stateless address autoconfiguration and dynamic DNS updates, and will have multiple addresses from multiple prefixes on a link So management tools must select appropriate addresses and allow for DNS names wherever possible

17 Renumbering IETF goal is to allow for automated, easy renumbering (assignment of prefixes to links) Router advertisements dynamically announce prefixes available on a link Stateless address autoconfiguration allows hosts to select addresses from new prefixes Prefix lifetimes for graceful transition from old to new prefixes Management tools opportunity: automating the details and the process of renumbering

18 Issues with SNMP MIBs need to be updated Current design is unified IPv4-IPv6, with single type for IP addresses: inetaddresstype, inetaddress MIB II updates published as Internet Drafts

19 Basic IP services DNS New AAAA RR for IPv6 addresses (A6 and DNAME are Experimental) Reverse zone is DHCPv6 Basic function similar to DHCP for IPv4 Likely to be used for DNS configuration of hosts Prefix delegation enhancement RADIUS RFC 3162

20 Deployment and coexistence IPv4 and IPv6 on the same network Likely initial deployment mode Core network devices will be dual-stack, forwarding both IPv4 and IPv6 Management of both IPv4 and IPv6 functions carried over IPv4 IPv6 service through an IPv4 core Service provider offers IPv6-only service to customers IPv6 tunneled through IPv4 core (6PE) to upstream connection Some NRENs deploying IPv6-only core network

21 Coexistence methods DSTM (Dual Stack Transition Method) for devices with both IPv4 and IPv6 stacks Tunneling 6PE: IPv6 over MPLS through IPv4-only core ISATAP: Automatic tunneling through designated routers Teredo: IPv6 in IPv4 UDP to traverse IPv4 NAT Translation NAT-PT: NAT with protocol translation Bump-in-stack: protocol translation in the host stack Application-level gateway (ALG)

22 Service provider issues Expected model is to assign /48 to customer Allows customer to subnet internally Global address assignment (NO NAT!!) Address auto-configuration and privacy addresses may be problematic for identity management Renumbering allows: Dynamic prefix assignment Switching between ISPs

23 Impact of IPv6 on management systems Changes to IP Address representation and storage Expanded use of DNS Extending to new functions Implementing new services and protocols Accommodate larger addresses Provide IPv6 transport Build new service or protocol engine

24 Resources Standards: IETF v6ops, ipv6 working groups RFCs and Internet Drafts Example deployment: 6net, WP2: IPv4-IPv6 Coexistence, Interworking and Migration WP3: Basic Network Services WP6: Network Management Architecture and Tools