{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

l11 IPv6,Anycast,Multicast

l11 IPv6,Anycast,Multicast - Anycast Communicate with any...

Info icon This preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon
Anycast Communicate with “any” one of a set of nodes Can do this with DNS $ dig www.google.com ... ;; ANSWER SECTION: www.google.com. 604799 IN CNAME www.l.google.com. www.l.google.com. 300 IN A 74.125.19.103 www.l.google.com. 300 IN A 74.125.19.104 www.l.google.com. 300 IN A 74.125.19.147 www.l.google.com. 300 IN A 74.125.19.99
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Anycast at IP layer DNS allows anycast through name address mappings Sometimes we need it at layer 3 itself - Single IP address refers to multiple hosts - Need to talk to any one of them Example: DNS root servers - Would like to scale number of root servers with Internet - Can’t use DNS (remember root servers hard-coded) - Want to query closest root server
Image of page 2
Anycast in Forwarding Tablse Remember, forwarding is longest-prefix-match An anycast address is a /32 address A single router may have multiple entries for the address Anycast best used in services where separate packets might go to different destinations
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The Cost A /32 routing entry! Multiple /32 routing entries!
Image of page 4
Further Advantages Geographic scoping Distributed Denial of Service (DDoS) - Load from DDoS is distributed across many anycast nodes F root server (192.5.5.241) now in 46 locations! Try the following: dig +norec @f.root-servers.net hostname.bind chaos txt
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
I think we have a problem - Projected use of /8 blocks - From “ A Pragmatic Report on IPv4 Address Space Consumption ,” Tony Main, Cisco Sys- tems.
Image of page 6
IPv6 Work started in 1994 Basic protocol published in 1998 [RFC 2460] Brief lull, the progress in 2003-6 Hard push within IETF today for adoption
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
IPv6 Key Features 128 bit addresses - Autoconfiguration Simplifies basic packet format through extension headers - 40 byte “base” header - Make uncommonly used fields optional
Image of page 8
IPv6 Addresses [RFC 4291] | n bits | 128-n bits | +-------------------------------+---------------------------------+ | subnet prefix | interface ID | +-------------------------------+---------------------------------+ Written as 8, ‘:’-separated 16-bit hex numbers - Example: 2001:470:806d:1:0:0:0:9 - Can omit a single run of 0s with “ :: - Use brackets in URLs: http://[2001:470:806d:1::9]:80/ - Can write low 32-bits like IPv4: 64:ff9b::171.66.3.9 Like IPv4, specify subnet prefix with ’/’ - E.g., 2001:db8:122:344::/64 Most IPv6 networks use 64-bit subnet prefix, and end users should receive multiple /64s [RFC 6177]
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
IPv6 address allocation Normal global unicast addresses start 2000::/3 - IANA doles out unicast prefixes to RIRs A few other special prefixes are assigned - :: (all 0s) is unspecified address, ::1 is localhost - Rest of 0::/8 used for IPv4 compatibility - fc00::/7 used for local addresses [RFC 4193] (kind of like IPv4 addresses 10/8, 172.16/20, 192.168/16 [RFC 1918] ) - fe80::/10 used for link-local addresses - ff00::/8 used for multicast Over 85% of address space reserved - In the unlikely event we exhaust 2000::/8 , can be more parsimonious with some other slice
Image of page 10
IPv6 multicast addresses | 8 | 4 | 4 | 112 bits | +------ -+----+----+---------------------------------------------+ |11111111|0RPT|scop| group ID | +--------+----+----+---------------------------------------------+ - T : 1 = transient , 0 = group ID assigned by IANA - P : 1 = address embeds global IPv6 prefix ( T must also be 1) - R : 1 = (requires T = P = 1) encodes rendezvous point Scope 1 = interface-local, 2 = link-local, . . .
Image of page 11

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 12
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}