Subject: Re: [Softwires] comments on draft-ietf-softwire-ipv6-6rd-03

From: WashamFan <[email-masked]>
Date: Tue, 12 Jan 2010 22:34:04 +0800

Hi,

> >>   The 6rd CE and BR SHOULD support the IPv6 Subnet-Router anycast
> >>    address [RFC4291] for its own 6rd delegated prefix.  This 
> allows, for
> >>    example, IPv6 ping messages to be sent to the 6rd Virtual Interface
> >>    itself for additional troubleshooting of the internal operation 
> of
> >>    6rd at a given CE or BR, over and above an IPv4 ping to the
> >>                                       ^^^^^^^^^^^^^^^^^^^ ( I don't 
> get it)
> >>    associated CE or BR IPv4 address.  In the case of the BR, the IPv4
> >>    address used to calculate the 6rd delegated prefix is the configured
> >>    BR IPv4 Address.
> >>      
> > we just tried to say that with a well known IPv6 address to ping 
> (subnet router anycast) then that can be used for troubleshooting. in 
> addition to using the IPv4 address. happy to edit if you have a 
> suggestion of better text.
> >    
> Washam - Point is that an IPv4 ping, and an IPv6 ping encapsulated in 
> 
> the same IPv4 address by 6rd both test the same reachability in terms 
> of 
> the CE to BR or CE to CE communication path, etc. Using IPv6 goes a 
> bit 
> further than that by ensuring that the 6rd mechanism itself is working 
> 
> correctly.

Thanks for the explanation. I know now, it is the idiom "over and above"
that kept confusing me before I consulted a native speaker. Personally,
I think it would be easier for non-English speaker like me to read if you
use "in addition to" or something similar instead. (I used to interpret it
as IPv6 ping over IPv4 ping which makes no sense ;-)

Besides, I wanna ask, are you saying IPv6 ping is only for the test between
CE and BR? I assume yes since anycast address is considered here.

washam

---

From: Mark Townsley <[email-masked]>
Date: Tue, 12 Jan 2010 15:59:01 +0100

> as IPv6 ping over IPv4 ping which makes no sense ;-)
Ah, I see. We'll work on something that avoids idioms here.
> CE and BR? I assume yes since anycast address is considered here.
The IPv6 anycast address here is to ping any CE or BR, and from any IPv6 
host. It's simply a way of relying on a known IPv6 address at any 6rd 
node to be used for isolated troubleshooting using IPv6 messages and the 
6rd encapsulation technique.

- Mark