Re: [mpls] [Bier] Encapsulation first nibble
Xuxiaohu <xuxiaohu@huawei.com> Tue, 17 March 2015 11:17 UTC
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From: Xuxiaohu <xuxiaohu@huawei.com>
To: Xuxiaohu <xuxiaohu@huawei.com>, "stbryant@cisco.com" <stbryant@cisco.com>, Eric C Rosen <erosen@juniper.net>, BIER <bier@ietf.org>
Thread-Topic: [Bier] Encapsulation first nibble
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Date: Tue, 17 Mar 2015 11:17:04 +0000
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Subject: Re: [mpls] [Bier] Encapsulation first nibble
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Another way is to add a protocol identifier field after the bottom of the label stack (https://tools.ietf.org/html/draft-xu-mpls-payload-protocol-identifier-00). In this way, we would not be bothered about the nibble issue anymore when proposing any new encapsulation header which may be encapsulated within an MPLS packet. Best regards, Xiaohu -----邮件原件----- 发件人: mpls [mailto:mpls-bounces@ietf.org] 代表 Xuxiaohu 发送时间: 2015年3月17日 18:49 收件人: stbryant@cisco.com; Eric C Rosen; BIER 抄送: mpls@ietf.org; sfc@ietf.org 主题: Re: [mpls] [Bier] Encapsulation first nibble I believe this should be applicable to the NSH as well (i.e., set the nibble to zero) if it's assumed that the NSH could be encapsulated within an MPLS packet. Best regards, Xiaohu -----邮件原件----- 发件人: BIER [mailto:bier-bounces@ietf.org] 代表 Stewart Bryant 发送时间: 2015年3月14日 3:54 收件人: Eric C Rosen; BIER 主题: Re: [Bier] Encapsulation first nibble On 13/03/2015 19:46, Eric C Rosen wrote: > Here's a small issue for the WG to consider. > > The mpls-bier-encapsulation draft specifies that the first nibble of > the encapsulation is to be a BIER encaps version number, initially 0. > The values 4 and 6 are excluded from the "version number" space, as > there are various heuristic procedures deployed that interpret those > values of the first nibble following the MPLS label stack as > identifying the payload to be an IP packet. > > However, there are also various deployed heuristics that may interpret > the values 0 and 1 as identifying a pseudowire payload, either data or > OAM. > > This raises the issue of whether we might be better off setting this > nibble to a fixed value, rather than trying to use it as a version > number. If we really need a version number in the encaps, perhaps it > should be someplace where it definitely won't impact any existing > heuristics. The safest value for the first nibble might be one of > the values 5-9, which are already assigned as IP Version Numbers, but > are assigned to things that (I think) don't actually exist. > > > > _______________________________________________ > BIER mailing list > BIER@ietf.org > https://www.ietf.org/mailman/listinfo/bier > I agree with Eric on this. I would set the nibble to zero which tells any parser that the payload is only understandable only by a node that knows the actions required by the BOS label. I think the ACH RFC says something like the above, but would have to go find the specific text. - Stewart _______________________________________________ BIER mailing list BIER@ietf.org https://www.ietf.org/mailman/listinfo/bier _______________________________________________ mpls mailing list mpls@ietf.org https://www.ietf.org/mailman/listinfo/mpls
- Re: [mpls] [Bier] Encapsulation first nibble Gregory Mirsky
- Re: [mpls] [Bier] Encapsulation first nibble Antoni Przygienda
- Re: [mpls] [Bier] Encapsulation first nibble Zhaohui (Jeffrey) Zhang
- Re: [mpls] [Bier] Encapsulation first nibble Xuxiaohu
- Re: [mpls] [Bier] Encapsulation first nibble Xuxiaohu
- Re: [mpls] [Bier] Encapsulation first nibble Eric C Rosen
- Re: [mpls] [Bier] Encapsulation first nibble Antoni Przygienda
- Re: [mpls] [Bier] Encapsulation first nibble Xuxiaohu
- [mpls] 答复: [Bier] Encapsulation first nibble Xuxiaohu
- [mpls] 答复: [Bier] Encapsulation first nibble Xuxiaohu
- Re: [mpls] [Bier] Encapsulation first nibble Xuxiaohu
- Re: [mpls] [Bier] Encapsulation first nibble Jeffrey (Zhaohui) Zhang
- Re: [mpls] [Bier] Encapsulation first nibble Ignas Bagdonas
- Re: [mpls] [Bier] Encapsulation first nibble UTTARO, JAMES
- Re: [mpls] [Bier] Encapsulation first nibble Stewart Bryant
- Re: [mpls] [Bier] Encapsulation first nibble Stewart Bryant (stbryant)
- Re: [mpls] [Bier] Encapsulation first nibble Tony Przygienda