RFC 1879 (rfc1879) - Page 2 of 6
Class A Subnet Experiment Results and Recommendations
Alternative Format: Original Text Document
RFC 1879 Class A Subnet Experiment January 1996
Initial predictions [3] seemed to indicate that the safest path for
an ISP that participates in such a routing system is to have -all- of
the ISP clients be either:
a) singly connected to one upstream ISP
OR
b) running a classless interior routing protocol
It is also noted that a network with default route may not notice it
has potential routing problems until it starts using subnets of
traditional A's internally.
Problems & Solutions
Operations
There were initial problems in at least one RIPE181 [4]
implementation. It is clear that operators need to register in the
Internet Routing Registry (IRR) all active aggregates and delegations
for any given prefix. Additionally, there need to be methods for
determining who is authoritative for announcing any given prefix.
It is expected that problems identified within the confines of this
experiment are applicable to some RFC 1597 prefixes or any "natural"
class "A" space.
Use of traceroute (LSRR) was critical for network troubleshooting
during this experiment. In current cisco IOS, coding the following
statement will disable LSRR and therefore inhibit cross-provider
troubleshooting:
no ip source-route
We recommend that this statement -NOT- be placed in active ISP cisco
configurations.
In general, there are serious weaknesses in the Inter-Provider
cooperation model and resolution of these problems is outside the
scope of this document. Perhaps the IEPG or any/all of the national
or continental operations bodies [5] will take this as an action item
for the continued health and viability of the Internet.
Manning Informational