From: swm@emanon.com
Date: Sun Feb 01 2009 - 00:49:41 ARST
Ahhhh... The fun stuff. Always good to cause some consternation. :)
RFC 3630 - OSPF extensions for TE actually makes a few references to BGP as
well, namely having to do with the BGP Router ID being set as the next-hop
address (peer-id) for correlation purposes.
So it looks like this is built into code now.
Always good to know although I apparantly haven't been devious enough lately
to run into a problem with it! (grin)
But good to have the routers!
Scott
---- Message from Hobbs <deadheadblues@gmail.com> at 2009-01-31 19:18:19
------
>Well since I got rack session going on:
>
>R6(config)#router bgp 256
>R6(config-router)#bgp router-id 0.0.0.1
>%Invalid router-id 0.0.0.1
>R6(config-router)#bgp router-id 255.255.255.255
>%Invalid router-id 255.255.255.255
>R6(config-router)#bgp router-id 224.0.0.1
>%Invalid router-id 224.0.0.1
>R6(config-router)#bgp router-id 223.255.255.255
>R6(config-router)#
>
>R6#sho ver | inc bin
>System image file is "flash:c2800nm-adventerprisek9-mz.124-3a.bin"
>
>
>}\/\/{
>| |
>(.)(.)
>| C |)
>(___/|
> )__|
> / \\
> / \\
>
>:D
>
>On Sat, Jan 31, 2009 at 6:56 PM, swm@emanon.com <swm@emanon.com> wrote:
>> The router-id in both is simply a 32-bit number.
>>
>> Your call.
>>
>> Scott
>>
>>
>> ---- Message from "ciscozest" <ciscozest@gmail.com> at 2009-02-01 08:11:46
>> ------
>>>
>>>
>>>So in case of OSPF and BGP exist on the same router, does the router ID
must
>> be pingable or just a valid IPv4 address?
>>>Thanks.
>>>
>>>
>>>
>>>From: Narbik Kocharians [mailto:narbikk@gmail.com]
>>>Sent: Sunday, 1 February 2009 4:26 AM
>>>To: ciscozest
>>>Cc: swm@emanon.com; Jared Scrivener; Jason Madsen; Cisco certification;
Cisco
>> certification
>>>Subject: Re: about OSPF router ID
>>>
>>>
>>>I totally agree with Scott, the OSPF router id is a 32 bit dotted decimal
>> number, it can be an IPv4 address, but it can also be any dotted decimal
>> number like "0.0.0.1" for R1 and so forth.
>>>
>>>
>>>
>>>One problem that you may run in to (In a CCIE LAB) is when you have OSPF
and
>> BGP with synchronization enabled in an AS, the router that redistributes
the
>> BGP routes into OSPF must have the same router-id configured on both
routing
>> protocols (meaning OSPF and BGP router-id must be identical on that
router)
>> and in this case you won't be able to use anything other than a valid IP
>> address, because BGP's router-id must be a valid IP address.
>>>
>>>
>>>
>>>Hope this helped.
>>>
>>>On Sat, Jan 31, 2009 at 3:57 AM, ciscozest <mailto:ciscozest@gmail.com >
>> wrote:
>>>Dear Scott, Jared, Roy and Jason,
>>>
>>>Thank you all for the input. Really appreciate that. Have a nice weekend
:)
>>>
>>>
>>>-----Original Message-----
>>>From: mailto:swm@emanon.com [mailto:mailto:swm@emanon.com ]
>>>Sent: Saturday, 31 January 2009 3:23 PM
>>>To: Jared Scrivener; 'Jason Madsen'; 'ciscozest'
>>>Cc: 'Cisco certification'; 'Cisco certification'
>>>
>>>
>>>Subject: RE: about OSPF router ID
>>>
>>>Actually, it not only doesn't need to be pingable, but it doesn't even
need
>> to be a valid IPv4 address. It's simply a 32-bit number.
>>>
>>>If you're bored, make your router-id's 240.1.1.1, 240.1.1.2, 240.1.1.3,
etc.
>> Definitely can't put that on an IP interface... Definitely can't ping it.
>> But it works just fine.
>>>
>>>Jared's got a point about name lookups, but on the other hand, if you
>> properly populate your DNS lookups you'll be good on that one!
>>>
>>>Real life, most people use a loopback, whatever your main management
>> interface happens to be. Just keeps things simple. But it's just a
32-bit
>> number, so the fact that it relates to an actual IP address is for OUR
>> benefit, not the routers'!
>>>
>>>Scott
>>>
>>>
>>>---- Message from "Jared Scrivener" <mailto:jscrivener@ipexpert.com > at
>> 2009-01-30 21:25:18 ------
>>>>Whilst it is true that an OSPF Router ID doesn't have to be pingable, it
>>>>generally makes life easier to use a reachable IP (normally Loopback 0).
>>>>
>>>>Let's say that you are asked to also turn on "ip ospf domain-lookup"
which
>>>>will translate your neighbor's Router-ID into a DNS name (which will
either
>>>>be defined by a hosts file or received via DNS).
>>>>
>>>>If you do it via hosts entries and your are ALSO a DNS server then your
DNS
>>>>clients would receive an unreachable IP address when they ping via DNS
>> name.
>>>>
>>>>I know that's a rare case, but given the nature of question
interdependency
>>>>on the lab (and the evil nature of workbook vendors) I personally use L0
as
>>>>my OSPF Router-ID (and set it manually using the "router-id" command)
every
>>>>time unless otherwise directed.
>>>>
>>>>Cheers,
>>>>
>>>>Jared Scrivener CCIE3 #16983 (R&S, Security, SP), CISSP
>>>>Technical Instructor - IPexpert, Inc.
>>>>Telephone: +1.810.326.1444
>>>>Fax: +1.810.454.0130
>>>>Mailto: mailto:jscrivener@ipexpert.com
>>>>
>>>>-----Original Message-----
>>>>From: mailto:nobody@groupstudy.com [mailto:mailto:nobody@groupstudy.com
]
>> On Behalf Of
>>>>Jason Madsen
>>>>Sent: Friday, 30 January 2009 9:01 PM
>>>>To: ciscozest
>>>>Cc: Cisco certification; Cisco certification
>>>>Subject: Re: about OSPF router ID
>>>>
>>>>OSPF Router IDs can be any UNIQUE IPv4 address...they don't have to be
>>>>addresses assigned to an interface.
>>>>
>>>>On Fri, Jan 30, 2009 at 6:56 PM, ciscozest <mailto:ciscozest@gmail.com >
>> wrote:
>>>>
>>>>> Hi all,
>>>>>
>>>>>
>>>>>
>>>>> I read Cisco press book stated that OSPF router ID do not need to be
>>>>> pingable. In this case if I use a router ID which is not assigned to
any
>>>>> interface on that router, would this cause any issue such as OSPF
>>>>> adjacency,
>>>>> LSA table advertisement, etc? Has anyone do this before and can
enlighten
>>>>> me? Thanks.
>>>>>
>>>>>
>>>>> Blogs and organic groups at http://www.ccie.net/"
>>>target="_blank
>>>>>
>>>>> _______________________________________________________________________
>>>>> Subscription information may be found at:
>>>>> http://www.groupstudy.com/list/CCIELab.html
>>>>
>>>>
>>>>Blogs and organic groups at http://www.ccie.net/
>>>>
>>>>_______________________________________________________________________
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>>>>
>>>Internal Virus Database is out of date.
>>>Checked by AVG - http://www.avg.com/
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2009/1/20
>> 14:34
>>>
>>>
>>>
>>>
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>>>
>>>
>>>
>>>
>>>
>>>
>>>--
>>>Narbik Kocharians
>>>CCSI#30832, CCIE# 12410 (R&S, SP, Security)
>>>http://www.MicronicsTraining.com www.MicronicsTraining.com
>>>http://www.Net-Workbooks.com www.Net-Workbooks.com
>>>Sr. Technical Instructor
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>> 17:31:00
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
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