One alternative to CIDR... ASAP
Tim Bass
bass at linux.silkroad.com
Sun Aug 13 20:32:18 UTC 1995
Friends:
People keep sending me e-mail asking for my ideas on alternatives to
renumbering and CIDR. Here is a very rough strawman idea just
posted to the CIDRD-WG. There are similar variations on this
ASN routing paradigm that also could be considered:
VR,
Tim
PS: I'm off to the Azores in Portugal Monday for three weeks, so
hopefully I can find net access to see how much of a flame-fest
my mbox is enjoying.....
*****************************************************************
STRAWMAN
Autonomous System Aggregation Protocol (ASAP)
---------------------------------------------
Too simple, by a simple minded person.... :-)
1) Modify IP code in routers to route with ASN numbers between
AS;
2) Modify core routers to add ASN numbers to IP packets by;
i.) Temporarily using TOS or similar field(s) in IP header;
ii.) Add proper hooks in next version of IP;
iii.) Some better idea.
3) Develop details of new routing algorithm to route, filter,
load balance, multi-home using ASN tags;
4) Modify core routers to add ASN tags to IP packets that do
not have ASN tags assigned by originating host (for
backwards compatability with version of TCP/IP that cannot
add their ASN numbers to IP headers (or a better idea);
5) Modify core routers to transfer routing from the ASAP protocol
to the appropriate IGP if-and-only-if ASN of destination matches
the current ASN;
6) Create simple UDP based algorithm (similar to DNS) that manages
a distibuted database that maps IP addresses to ASN numbers.
For example:
When sending a packet, the kernal checks its cache for a map between
the IP address and ASN number. If it existing is the cache (get a hit)
it adds the ASN destination number to the IP header..... if not
the router or host sends a UDP packet to a distributed database that
maintains the mappings.. (these could be local, remote, but distributed
and caching each other ... in a similar, but more efficient manner than
DNS (after all how often do IP networks change their home ASN)
(instead of ARP.... its ASNRP...... ;-)
7) Create another database of SUPERNETTED ASN numbers for IP service providers
that aggregate current ASN numbers into some meaningful structure and
provide distribued SUPER-ASN to SUPER-ASN routing.
8) More ideas to develop and refine....
Advantages:
1) IP address space allocation is simplifed and renumbering not necessary;
2) ASN routing reduces the size of the routing tables ;
3) SUPER-ASN routing further reduces the size of ASAP routing tables;
4) Routers can add ASN tags to IP packets until users migrate to new IP
kernels;
5) More.... but I'm packing for a trip...
Disadvantages:
1) Must create new ASAP protocol and SUPER-ASAP protocol;
2) Must create distributed ASN-NETWORK database;
3) IP code must be modified and upgraded;
4) Non-cached initial packets will route slower mapping
destination ASN to destination IP address.
5) Also more disadvantages.....
Just a start.... needs work.... but living in a plane is a real
drain.. :-)
Tim
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