Dear Chairs， we have addressed all the received comments on the draft at the following link: draft-cheng-rtgwg-srv6-multihome-egress-protection-05 Furthermore, we have successfully verified the proposed solution with running code.
In light of these, we kindly request the chairs to consider the adoption of this draft. Happy New Year！ Weiqiang Cheng From: 姜文颖 Date: 2023-09-20 15:50 To: Yingzhen Qu CC: rtgwg; draft-cheng-rtgwg-sr Subject: Re:Re: Questions about draft-cheng-rtgwg-srv6-multihome-egress-protection Hi Yingzhen: We have addressed all the comments received till now. Co-authors believe this document is mature enough, and we hope to request WG adaptation. 1. Comments1: About PSD definition, in section 3.2, there are the following texts: " A penultimate SRv6 Segment Endpoint node is one that, as part of the SID processing, copies the last SID from the SRH into the IPv6 Destination Address and decrements the Segments Left value from one to zero. " [wenying] In Section 3.2 of "Version 05", we have deleted the above description. " The PSD operation only takes place at the egress node and does not happen at any transit node. When a SID of PSD flavor is processed at a transit node, the PSD behavior is not performed as described in the pseudocode below since Segments Left would not be 1 or 0. " so to my understanding, P2 is the penultimate endpoint in the example in Figure 1, correct? however there is "PSD-flavored SID" on PE3. Please clarify. [Zhibo] Yes, your understanding is correct. We will modify the description in the next version to avoid ambiguity. [Yingzhen]: Please do. The second quoted text here is not correct. [wenying] In Section 3.2 of "Version 05", we have modified the second quoted text as follows to avoid ambiguity： “When a node (PE3 in Figure 1) receives a packet whose IPv6 DA is a SID with PSD Flavor located in the penultimate position of the SRH Segment List array，and that SID is a local SID,it indicates to remove the outer encapsulation of the packet, and forward the packet according to the exposed packet. ...... Due to the above pseudocode modification,the PSD operation only takes place at the egress node and does not happen at any transit node. When a SID of PSD flavor is processed at a transit node, the PSD behavior is not performed since Segments Left would not be 1 or 0.” 2. Comments2: In Section 4, "After the configuration, PE1 determines that PE3's backup SID is PE4's VPN SID through the routing optimization strategy of BGP." Can you please elaborate how PE1 decides PE4 to be the backup SID? What if the path for P2 to reach PE4 is P2->PE3->PE4? [Zhibo] According to the BGP route selection principle, the ingress PE node selects the preferred route as the primary node and the second-best route as the backup node. After egress protection is enabled, if PE3 fails, P2 forwards traffic to PE4. If PE3 is the next hop of P2, P2 will forwards traffic to PE4 through the TI-LFA backup path. This solution does not affect the implementation of this solution. [wenying] In Section 4 of "Version 05", we added the following explanation to provide clarification: “After the configuration, according to the BGP route selection principle, the ingress PE node selects the preferred route as the primary node and the second-best route as the backup node. PE1 determines that PE3 is the primary egress node and PE4 is the backup egress node. PE3's backup SID is PE4's VPN SID.” 3. Comments3: In section 3.4, it mentions that P2 could be several hops away from the egress node. In this case, if PE3 fails, how does P2 detect the failure of PE3 quickly? What if a link between P2 and PE3 fails? [Zhibo] P2 detect the failure of PE3 via: • IGP convergence • BFD detection Traditional FRR also maximizes the protection scope and preferentially considers node faults without distinguishing whether a link fault or node fault occurs. BR. wenying -----Original Message----- From: Yingzhen Qu [mailto:yingzhen.i...@gmail.com] Sent: Friday, August 11, 2023 4:30 AM To: Huzhibo Cc: draft-cheng-rtgwg-srv6-multihome-egress-protect...@ietf.org; RTGWG Subject: Re: Questions about draft-cheng-rtgwg-srv6-multihome-egress-protection Hi Zhibo, Please see my reply below. Thanks, Yingzhen On Tue, Aug 8, 2023 at 6:15AM Huzhibo <huzh...@huawei.com> wrote: > Hi Yingzhen： > > Thanks for your comments, please see inline. > > > > Thanks > > Zhibo > > *From:* rtgwg [mailto:rtgwg-boun...@ietf.org] *On Behalf Of *Yingzhen Qu > *Sent:* Saturday, August 5, 2023 9:00 AM > *To:* draft-cheng-rtgwg-srv6-multihome-egress-protect...@ietf.org; RTGWG < > rtgwg@ietf.org> > *Subject:* Questions about > draft-cheng-rtgwg-srv6-multihome-egress-protection > > > > Hi Authors, > > > > (as individual contributor) > > > > I reviewed the draft, and have the following questions: > > > > 1. > > About PSD definition, in section 3.2, there are the following texts: > > " A penultimate SRv6 Segment Endpoint node is one that, as part of the > > SID processing, copies the last SID from the SRH into the IPv6 > > Destination Address and decrements the Segments Left value from one > > to zero. > > " > > " The PSD operation *only takes place at the egress node *and does not > > happen at any transit node. When a SID of PSD flavor is processed at > > a transit node, the PSD behavior is not performed as described in > > the pseudocode below since Segments Left would not be 1 or 0. > > " > > so to my understanding, P2 is the penultimate endpoint in the example in > Figure 1, correct? however there is "PSD-flavored SID" on PE3. Please > clarify. > > [Zhibo] Yes, your understanding is correct. We will modify the description > in the next version to avoid ambiguity. > > > [Yingzhen]: Please do. The second quoted text here is not correct. 2. > > In Section 4, "After the configuration, PE1 determines that PE3's backup > SID is PE4's VPN SID through the routing optimization strategy of BGP." From: rtgwg [mailto:rtgwg-boun...@ietf.org] On Behalf Of Yingzhen Qu Sent: Saturday, August 5, 2023 9:00 AM To: draft-cheng-rtgwg-srv6-multihome-egress-protect...@ietf.org; RTGWG <rtgwg@ietf.org> Subject: Questions about draft-cheng-rtgwg-srv6-multihome-egress-protection Hi Authors, (as individual contributor) I reviewed the draft, and have the following questions: 1. About PSD definition, in section 3.2, there are the following texts: " A penultimate SRv6 Segment Endpoint node is one that, as part of the SID processing, copies the last SID from the SRH into the IPv6 Destination Address and decrements the Segments Left value from one to zero. " " The PSD operation only takes place at the egress node and does not happen at any transit node. When a SID of PSD flavor is processed at a transit node, the PSD behavior is not performed as described in the pseudocode below since Segments Left would not be 1 or 0. " so to my understanding, P2 is the penultimate endpoint in the example in Figure 1, correct? however there is "PSD-flavored SID" on PE3. Please clarify. [Zhibo] Yes, your understanding is correct. We will modify the description in the next version to avoid ambiguity. 2. In Section 4, "After the configuration, PE1 determines that PE3's backup SID is PE4's VPN SID through the routing optimization strategy of BGP." . Can you please elaborate how PE1 decides PE4 to be the backup SID? What if the path for P2 to reach PE4 is P2->PE3->PE4? [Zhibo] According to the BGP route selection principle, the ingress PE node selects the preferred route as the primary node and the second-best route as the backup node. After egress protection is enabled, if PE3 fails, P2 forwards traffic to PE4. If PE3 is the next hop of P2, P2 will forwards traffic to PE4 through the TI-LFA backup path. This solution does not affect the implementation of this solution. 3. In section 3.4, it mentions that P2 could be several hops away from the egress node. In this case, if PE3 fails, how does P2 detect the failure of PE3 quickly? What if a link between P2 and PE3 fails? [Zhibo] P2 detect the failure of PE3 via: • IGP convergence • BFD detection Traditional FRR also maximizes the protection scope and preferentially considers node faults without distinguishing whether a link fault or node fault occurs. Thanks, Yingzhen ------------------------------------------------------------------------------------------------------------------------------------- 本邮件及其附件含有新华三集团的保密信息，仅限于发送给上面地址中列出 的个人或群组。禁止任何其他人以任何形式使用（包括但不限于全部或部分地泄露、复制、 或散发）本邮件中的信息。如果您错收了本邮件，请您立即电话或邮件通知发件人并删除本 邮件！ This e-mail and its attachments contain confidential information from New H3C, which is intended only for the person or entity whose address is listed above. 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