[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Comments on draft-wbeebee-ipv6-cpe-router-01.txt

On 20 jul 2008, at 15:45, Hemant Singh (shemant) wrote:


3. I disagree with the behavior suggested for "unnumbered" model. I
don't think a CPE router should automatically open up a maintenance
loopback interface just because it doesn't get a global IP address.



<hs>
Would you PLEASE use normal quoting techniques? Reading email costs enough time as it is without everyone doing stuff in their own particular way so automation and habits don't work. 


Not quite.  The unnumbered model is clearly saying the WAN interface
only acquires on a link-local address. But the WAN interface of the CPE 
Router has got to have a global IPv6 address.
You are being extremely imprecise. That is one of the reasons your draft is in such bad shape. 

The INTERFACE doesn't need a global address, but the ROUTER does.


So what choice does the
CPE Router have but to automatically spawn a Loopback interface that
will get assigned a global IPv6 address
When you need to create a packet, use a source address from another interface that you have, i.e. a LAN interface. I believe this is explained in the base IPv6 specs. Or ask within your company about the behavior of "ipv6 unnumbered ..." 


(using SLAAC,
Creating addresses using stateless autoconfig on an interface different than the one where the RAs were received is very wrong. 


DHCPv6
Using DHCPv6 address configuration on a router makes no sense in my opinion. 


stateless DHCPv6 to acquire an IA_PD).
I don't think prefix delegation is possible in the stateless version of DHCPv6. 

On 20 jul 2008, at 15:51, Hemant Singh (shemant) wrote:


The draft clearly says what ICMPv6 errors are returned by the CPE
Router, so it's not like the CPE Router is not responding to any ICMPv6 
request.


Good.


Existing IPv4 routers do have a ping disable feature where the
router is configured to not respond to pings.
You are again using imprecise terminology. What you mean is IPv4 CPEs with NAT functionality. That has little to do with routing. For IPv6, CPEs do have to be real routers and conform to normal router behavior unless we specify exceptions. 

It is of course allowed to not return echo replies.
However, since the router MUST generate other ICMPv6 messages under other circumstances, not replying to pings doesn't make the router invisible so there is little point in not returning ping replies. 


I also said on this
thread that if the CPE Router does respond to pings, the CPE Router
needs to rate limit incoming ping reqs.
You say that you want to rate limit INCOMING pings. (Which is useless anyway because the LAN bandwidth is much higher than the WAN bandwdith.) If you want to do this, it makes no sense to tie that to whether or not ping replies are sent. For the router itself this is a non-issue because the IPv6 specs mandate that ICMPv6 messages are rate limited anyway. 

On 20 jul 2008, at 16:43, Hemant Singh (shemant) wrote:


Please see the complete uRPF thread that we discussed on this mailer -
they were emails between July 15 - 16th, 2008.
I read it earlier today. It didn't make much sense to me. But now it occurs to me that you actually want to run uRPF on the CPE itself. I don't see how that's useful. What you want to do is filter out outgoing packets on the WAN interface if they don't have a source address that is either in the prefix delegated by the ISP or have the router's own WAN address as a source address.