Re: 6to4 on Sprint Wireless Broadband

[Joe Abley <jabley () hopcount ca>]

On 2010-02-27, at 10:13, Izaac wrote:

> A few months ago, is appears that Sprint started dropping 6to4
> encapsulated packets.  Egress is fine.  Ingress silently drops.  Anyone
> see anything similar?  Or am I the only guy crazy enough to be doing
> this sort of thing in the first place?

6to4 is a method for tunnelling v6 over v4 without statically-configuring endpoints. The encapsulation used is 
protocol-41, i.e. the same as "tunnel mode ipv6ip" in IOS or "interfaces ip-a/b/c" in JUNOS. It seems unlikely that 
Spring has decided to block IPv4 packets with protocol 41 payload.

What seems far more likely is that the relay routers used for return packets from the hosts you are trying to talk to 
are hitting a broken 6to4 relay router, and hence the return traffic is being (from your perspective) silently 
discarded.


Joe