SRAM-based IP Forwarding Eliminates the Need for Route Aggregation
draft-whittle-sram-ip-forwarding-01
| Document | Type |
Expired Internet-Draft
(individual)
Expired & archived
|
|
|---|---|---|---|
| Author | Robin Whittle | ||
| Last updated | 2007-04-02 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | Expired | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:
Abstract
I propose a simple, low-cost, low-power, Static RAM (SRAM) based architecture for the Forwarding Information Base (FIB) function of transit and border routers in the Default Free Zone (DFZ) of the Internet. This will provide direct hardware forwarding irrespective of the size of the "global BGP routing table", within the current IPv4 convention of limiting advertised prefixes to no longer than /24. Routers with this or a similar architecture provide the only elegant hardware solution to the problem of route disaggregation, which is unavoidable due to increasing numbers of ISPs and Autonomous System (AS) end-users who need to advertise their prefixes on topologically diverse parts of the network, for purposes including multihoming and traffic engineering. Router hardware limitations with respect to route disaggregation could also be eliminated for IPv6, by adding further SRAMs or, on a more limited basis, by using spare space in the SRAM which is required for IPv4. Two additional SRAMs and a reallocation of the existing 2000::/3 global unicast allocations to a smaller range - for instance 2000::/10 - would provide for Provider Independent (PI) /32 allocations to 4 million ISPs and multihomed end-users. Each /32 assignment could be advertised as up to eight /35 prefixes - each of which provides 8192 /48 user networks. A less disruptive alternative to reallocating existing IPv6 global unicast addresses would be to define a /10 prefix - inside or outside 2000::/3 - for new PI assignments to ISPs and AS end-users with the long-term assurance of rapid SRAM-based forwarding for prefixes as short as /35, without concern for route aggregation or network topology. It may be feasible, for a decade or more, to handle IPv6 without an addition SRAM chip. Unused space in the IPv4 chip (or two chips for larger routers) would map 2,097,152 /35 prefixes - for instance to support PI assignments of /32 prefixes to 262,144 ISPs and AS end-users. This would provide 17 billion /48 prefixes - the standard assignment for non-AS end-users.
Authors
(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)