Re: MPLS EIGRP backdoor links - SoO

I too VERY MUCH agree with this statement.

Paul

-- 
Paul Negron
CCIE# 14856 CCSI# 22752
Senior Technical Instructor
> From: Brian McGahan <bmcgahan_at_ine.com>
> Reply-To: Brian McGahan <bmcgahan_at_ine.com>
> Date: Tue, 1 Nov 2011 21:20:13 -0500
> To: Jochen Bartl <jochen.bartl_at_gmail.com>
> Cc: Tom Kacprzynski <tom.kac_at_gmail.com>, Cisco certification
> <ccielab_at_groupstudy.com>
> Conversation: MPLS EIGRP backdoor links - SoO
> Subject: Re: MPLS EIGRP backdoor links - SoO
> 
> As a side note, EIGRP SoO is a legacy feature that's not needed anymore,
> because the EIGRP Cost Community encodes the individual vectors of the
> composite metric calculation into BGP. This way the remote sites run a normal
> feasibility condition against the end to end path, and it's not possible to
> cause a loop between sites.
> 
> SoO isn't needed unless you're running old code that doesn't support Cost
> Community. It's possible you could get tested on it in the lab but it's not a
> practical problem anymore.
> 
> Brian McGahan, CCIE #8593 (R&S/SP/Security)
> bmcgahan_at_INE.com
> 
> Internetwork Expert, Inc.
> http://www.INE.com
> 
> On Nov 1, 2011, at 5:22 PM, "Jochen Bartl" <jochen.bartl_at_gmail.com> wrote:
> 
>> Since Paul has already mentioned that you can verify the SoO value
>> with "show ip eigrp topology XXXX", I would like to throw in some
>> additional info here. I`ve built a mini lab because I wanted to know
>> in detail how EIGRP carries the SoO value across the backdoor link.
>> 
>> After capturing some packets[1] on the backdoor link I could find out
>> that EIGRP is using the TLV type 260 for SoO. The data inside the TLV
>> looks something like this.
>> 
>> 01 04 -> TLV Type (260)
>> 00 14 -> TLV Length: 20 bytes
>> 0a 00 19 00 -> TLV references IP routing TLV with route 10.0.25.0
>> 00 00 00 -> Not sure yet?
>> 08 -> Ext Community Lengh? 8 bytes
>> 00 03 -> Ext Community Type?
>> 00 64 00 00 00 02 -> SOO Ext communit value: 100:2
>> 
>> I haven't figured out all the header fields yet, but I could at least
>> identify the SoO value of 100:2 in the last 6 bytes of the TLV. The
>> hex data is from packet 38 in the capture file[1]. Wireshark/Scapy
>> doesn't decode the TLV at the moment, but I promise to write a patch
>> as soon as I've identified all the header fields correctly ;-)
>> 
>> Petr Lapukhov has also written a great document about EIGRP SoO:
>> 
http://blog.ine.com/2010/04/29/understanding-eigrp-soo-and-bgp-cost-community>>
/
>> 
>> Best regards,
>> 
>> Jochen
>> 
>> 
>> 1) http://www.cloudshark.org/captures/327a223fadf3
>> 
>> On Tue, Nov 1, 2011 at 8:14 PM, Tom Kacprzynski <tom.kac_at_gmail.com> wrote:
>>> Hello,
>>> I'm working on a lab using EIGRP as the protocol for MPLS VPN. This
>>> scenario has a backdoor link. I'm testing the Site of Origin feature, but
>>> can't seem to find any way to check the actual SoO on the CE router using
>>> EIGRP commands. Does anyone know how/if I could do that?
>>> 
>>> I can see it in BGP table but how do I see it in EIGRP
>>> 
>>> Rack1R6#sh ip bgp vpnv4 rd 100:1 155.1.67.0/24
>>> BGP routing table entry for 100:1:155.1.67.0/24, version 338
>>> Paths: (1 available, best #1, table VPN-A)
>>> Advertised to update-groups:
>>>       1
>>> Local
>>>   0.0.0.0 from 0.0.0.0 (150.1.6.6)
>>>     Origin incomplete, metric 0, localpref 100, weight 32768, valid,
>>> sourced, best
>>>     Extended Community: SoO:100:60 RT:100:1
>>> Cost:pre-bestpath:128:28160                  <----------------------
>>>       0x8800:32768:0 0x8801:10:2560 0x8802:65280:25600 0x8803:65281:1500
>>>     mpls labels in/out 22/nolabel(VPN-A)
>>> 
>>> 
>>> 
>>> Thank you,
>>> 
>>> Tom
>>> 
>>> 
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