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Re: Fwd: Re: TOS reserved bits 6/7 and routing protocols posted 08/03/2006
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>Everybody is confusing this with IPP 6 or 7, which is 110/111 in the
>first three bits of said byte.
>

I think the original poster almost certainly meant IP Prec/CS 6/7, hence my response (it's a common question). And, yeah, hopefully I know where the IP Prec bits sit in the TOS octet :)


>I know that over-thinking questions is a bad thing, but ...
>
>Mark Lewis @ 3/8/2006 14:22 -0400 dixit:
>> Hi,
>> 
>> Routing protocols such as BGP are marked with IP Prec/CS 6 by originating routers.
>> 
>> Here's a list:
>> 
>> EGP/IGP/MCAST PROT: BGP, EIGRP, OSPF, RIP, PIM, MSDP, IGMP -- all marked with IP Prec/CS 6.
>> 
>> Other misc control protocols: LDP, RSVP-TE, L2TP control traffic, BFD-- all marked IP Prec/CS 6.
>> 
>> Management/diagnostics protocols: ICMP, NTP, Telnet-- all marked IP Prec/CS 6.
>> 
>> You'll notice that lack of protocols that marked CS7! There's a bit of confusion because IP Prec 6 is 'Internetwork Control' and IP Prec 7 is 'Network Control'. But Cisco routers don't mark any routing/control/management protocol traffic with IP Prec 7.
>> 
>> If you are creating a QoS policy/design for a network, then you also might like to do a bit of research on 'PAK_PRIORITY' (an internal flag that routers use to ensure that locally generated control traffic is prioritized).
>> 
>> HTH,
>> 
>> Mark
>> 
>> CCIE#6280 / CCSI#21051 / JNCIS#121 / etc.
>> 
>> Author:
>> 
>> www.ciscopress.com/title/1587051796
>> 
>> www.ciscopress.com/title/1587051044
>> 
>> 
>> 
>> 
>>> From: Carlos G Mendioroz <tron@xxxxxxxxxxx>
>>> Reply-To: Carlos G Mendioroz <tron@xxxxxxxxxxx>
>>> To: CCIEBOB <cciebob@xxxxxxxxxxx>
>>> CC: ccielab@xxxxxxxxxxxxxx
>>> Subject: Re: TOS reserved bits 6/7 and routing protocols
>>> Date: Thu, 03 Aug 2006 13:45:21 -0400
>>>
>>> Might it be that that person confused IPP 6/7 whith ToS bits 6-7 ?
>>> It seems to be a common thing :)
>>>
>>> CCIEBOB @ 2/8/2006 10:59 -0400 dixit:
>>>> Hello all.  I was recently told that some routing protocols (BGP) uses 
>>> the reserved TOS bit for routing protocol establishment and updates.  I 
>>> could not find any documentation to support this.   Does any one know if 
>>> this statement is correct, and if so where can I find documentation on it?  
>>> TIA. Bob
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