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Re: [mpls] [Bier] Encapsulation first nibble

Antoni Przygienda <antoni.przygienda@ericsson.com> Tue, 17 March 2015 17:15 UTC

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From: Antoni Przygienda <antoni.przygienda@ericsson.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 17:15:31 +0000
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Subject: Re: [mpls] [Bier] Encapsulation first nibble
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Not being much of an encapsulation, data plane guy myself, I wonder a tad how hacky those 'heuristics' are.  Last label indicates clearly a BIER header is following. For the LSRs that do not support BIER and do not parse the BIER encaps there is no reason to look 'behind the label'.  Multiple sub-domains allow for clean separation of traffic with different properties if needed and with that there is even less reason for some kind of 'heuristic' DPI

Now, given some 'heuristics' are in place no matter what value we put into the nibble, sooner or later we'll collide with it no matter what value we pick since such 'heuristics' basically try to parse bits without understanding their context and with that can easily mistake an 'eye' for an 'I' or an 'aye'. 

--- tony

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