Hi Jeff, I hope you will agree with my using your response to continue the discussion. Please find my notes below under the GIM2>> tag. I will respond to other discussion topics in another follow-up mail.
Regards, Greg On Thu, Apr 6, 2023 at 7:28 AM Jeffrey Haas <[email protected]> wrote: > Xiao Min, > > Thanks for addressing Greg's comments. I some additional comment on > Greg's points: > GIM2>> I greatly appreciate the attention Xiao Min extended to my comments. > > > On Apr 6, 2023, at 3:35 AM, <[email protected]> <[email protected]> > wrote: > > - > > The draft describes how the destination IP address of the Echo packet > is set. Are there any special considerations for selecting IPv6 destination > address? > > [XM]>>> The draft currently says "Device A would send BFD Unaffiliated > Echo packets with IP destination address destined for itself, such as the > IP address of interface 1 of device A". No any special considerations. > > > One of the considerations may be whether a IPv6 link local address is > preferable to a global address. > > The only consideration for the draft as it is written is that the address > used as the destination may be looped back by the unaffiliated device. > Link local helps address the security considerations that impact this > feature, and it might be worth noting that when link local can be used for > the use case that it assists in this point. > > > - > > Also, are there any special considerations for selecting the source IP > address for IPv4 and/or IPv6 network? > > [XM]>>> No. If you have any suggestions, please let me know. :) > > > Since the feature is intended to be used for single-hop, the source > address SHOULD be an address on the shared subnet with the interface of the > device that is looping the packets back. Perhaps it might even be > reasonable to require that the source and destination addresses are > identical when possible? > GIM2>> As I understand RFC 5881 <https://www.rfc-editor.org/rfc/rfc5881>, Section 4 recommends not to use an address on the same network as the destination IP address, nor use a link-local IPv6 address as the source IP address for an Echo message: In particular, the source address SHOULD NOT be part of the subnet bound to the interface over which the BFD Echo packet is being transmitted, and it SHOULD NOT be an IPv6 link-local address, unless it is known by other means that the remote system will not send Redirects. Do you think that the normative part of Section 4 is applicable to draft-ietf-bfd-unaffiliated-echo? > > Where this may complicate procedure is the initial demultiplexing step > when the session is Down. Once the session is Up, the Discriminators can > be used for this purpose. > > -- Jeff > >
