From: Carlos G Mendioroz (tron@huapi.ba.ar)
Date: Thu Aug 03 2006 - 15:50:26 ART
Mark,
subject says "TOS reserved bits 6/7"
i.e. DS byte ECT/CE bits... last two bits of the TOS byte.
Everybody is confusing this with IPP 6 or 7, which is 110/111 in the
first three bits of said byte.
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@huapi.ba.ar>
>> Reply-To: Carlos G Mendioroz <tron@huapi.ba.ar>
>> To: CCIEBOB <cciebob@comcast.net>
>> CC: ccielab@groupstudy.com
>> 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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