Re: Someone Please Help Me Understand

[Faisal Imtiaz <faisal () snappytelecom net>]

Eric,
There is no simple cut and dry way of troubleshooting such a situation, other than need to look at the problem in 
multiple different ways..
It also helps in being able to do some comparative test/results with another nearby network...

It is also not un-common to have to shutdown a peer v.s prepend.. when troubleshooting.
One has to keep in mind that many of the IP Transit networks use local pref for customer routes, thus nullifying 
(ignore) the AS prepends.
Each provider is different, HE does not have a published set of communities, thus effectively do not allow their 
customers to do any significant traffic 
engineer.. (anyone from HE, if I am wrong, please feel free to correct me). 
Level3 by default overrides any AS prepends with local pref, but does allow it's customers to use communities to 
override those settings.

> > . I am not trying to publically shame or air dirty laundry, I am just trying to
> understand the situation more.  CDNs bring a whole new level I have yet to
> comprehend with multicast DNS and GeoIP responses...


Understood, I have been there so I can relate. Nanog is a great place to learn, even when asking dumb questions, folks 
here have been very supportive in explaining, and every now and then one sees a sarcastic reply, but overall I cannot 
say I have ever had anyone treat me in a condescending manner.

My humble suggestion is that you start with simple stuff first .. i.e. bgp traffic engineering before trying to wrap 
your head around multicast DNS and GeoIP response... I often find the answer to complex issues to be in the simple 
stuff, which often gets overlooked !

:)


Faisal Imtiaz
Snappy Internet & Telecom
7266 SW 48 Street
Miami, FL 33155
Tel: 305 663 5518 x 232

Help-desk: (305)663-5518 Option 2 or Email: Support () Snappytelecom net

----- Original Message -----
> From: "Eric Rogers" <ecrogers () precisionds com>
> To: "Faisal Imtiaz" <faisal () snappytelecom net>
> Cc: "nanog list" <nanog () nanog org>
> Sent: Monday, April 4, 2016 8:46:41 AM
> Subject: RE: Someone Please Help Me Understand

> Thanks Faisal,
>
> I appreciate the time you took and the detail you have placed.  I did try
> prepending our HE connection thinking it was an issue via HE, and we started
> going out Level3, and it also went to Dallas with nearly the same packet loss.
> I don't know what the return path is/was, but through another provider, it
> also showed major packet loss.  That leads me to believe that FB is/was having
> issues in Dallas.  Maybe on their peering port?  I have since found out they
> don't peer through the route servers, but only directly through the exchanges
> (direct peering relationship).  I have since submitted a peering request to FB
> and also submitted a request to their NOC to look at the packet loss and why we
> are getting Dallas IPs.  I have not received a response to either.
>
> I can use the community strings to manipulate our announcement of our routes,
> but won't DNS tell the browser what IP to ultimately get the data?
>
> I am not trying to publically shame or air dirty laundry, I am just trying to
> understand the situation more.  CDNs bring a whole new level I have yet to
> comprehend with multicast DNS and GeoIP responses...
>
> Eric Rogers
> PDS Connect
> www.pdsconnect.me
> (317) 831-3000 x200
>
>
> -----Original Message-----
> From: Faisal Imtiaz [mailto:faisal () snappytelecom net]
> Sent: Sunday, April 3, 2016 8:27 PM
> To: Eric Rogers
> Cc: nanog list
> Subject: Re: Someone Please Help Me Understand
>
> Hi Eric,
>
> With this type of connectivity you have to pay attention to Traffic
> Engineering...
>
> And when I say, traffic engineering, I mean both ways.. how you are sending
> traffic to them along with how they are sending traffic to you... (sometimes a
> bit more challenging to do).
>
> I will give you two specific example, just to illustrate the point...
>
> We are located in the east coast, we have ip transit to Cogent network, via one
> intermediary ASN.
> We also have IP Transit with GTT and Hibernia networks.
> We also have direct peering on multiple Peering Fabrics.
>
> 1st cases...
> We have our outbound traffic engineered to prefer direct routes.. e.g. when
> sending traffic to Cogent, we send it out via the intermediary ASN to Cogent.
> However when traffic is coming back from Cogent.... they see our prefixes via
> intermediary ASN as well as Hibernia Networks, since Hibernia networks is a
> lower ASN, they prefer that route....
> So, one can say, no big deal, except, Hibernia Networks connects to Cogent on
> the West Coast !... so our return traffic is going from the east coast to west
> coast and them back to east coast....
> So one can easily say... Houston we have a problem !...
>
> 2nd Case..
> We are peered with some networks at Telx TIE, via one of our (intermediary)
> ASN...So while we can send traffic over to that network via our ASN, however
> that networks sees our prefixes via our (intermediary) ASN as Hibernia as
> well.... Hibernia being a lower ASN, they send traffic back to us via them...
>
> In both cases we use communities to take corrective action....
>
> Moral of the story is..... just because you have multiple peers, and peer with
> folks on the Peering Fabric, the default configuration of BGP will not
> AUTOMAGICALY  optimize the paths in your favor....
>
> And thus the condition you describe will be the result...
>
> Faisal Imtiaz
> Snappy Internet & Telecom
> 7266 SW 48 Street
> Miami, FL 33155
> Tel: 305 663 5518 x 232
>
> Help-desk: (305)663-5518 Option 2 or Email: Support () Snappytelecom net
>
> ----- Original Message -----
> > From: "Eric Rogers" <ecrogers () precisionds com>
> > To: "nanog list" <nanog () nanog org>
> > Sent: Saturday, April 2, 2016 1:54:40 PM
> > Subject: Someone Please Help Me Understand
>
> > Ok, I'm trying to learn, so bear with me.
> >
> >
> >
> > We are an ISP in Indianapolis that has full routes from 3 different
> > providers HE.Net in Columbus OH being one.  We also are peered with 2
> > peering exchanges, including EquinixIX in Chicago.  The problem is
> > Instagram and Facebook (same company, I know) for our customers seems
> > very slow.
> >
> >
> >
> > This is where I need a way to troubleshoot/understand more.  I did a
> > traceroute to the IP that is serving the pictures, and it resolves to
> > the FBCDN servers in Dallas, and is showing packet loss and pings once
> > it hits Dallas, and are in the 1xxs of ms.
> >
> >
> >
> > Tracing route to instagram-p3-shv-01-dfw1.fbcdn.net [31.13.66.52]
> >
> > over a maximum of 30 hops:
> >
> >
> >
> >  1     4 ms     3 ms     4 ms  10.7.0.1
> >
> >  2    20 ms    43 ms    42 ms  inmtvlobs-rtr-01.dynamic.pdsconnect.me
> > [192.69.57.1]
> >
> >  3    25 ms    47 ms    29 ms
> > inmtvlmwt-rtr-01.infrastructure.pdsconnect.me [192.69.48.162]
> >
> >  4    46 ms    32 ms    58 ms
> > inindyhen-core1.infrastructure.pdsconnect.me [192.69.48.193]
> >
> >  5    36 ms    53 ms    51 ms  ge2-4.core1.cmh1.he.net [184.105.32.1]
> >
> >  6    47 ms    41 ms    75 ms  10ge1-2.core1.chi1.he.net
> > [184.105.222.165]
> >
> >  7    57 ms    57 ms    53 ms  100ge14-1.core2.chi1.he.net
> > [184.105.81.97]
> >
> >  8    57 ms    73 ms    84 ms  100ge12-1.core1.mci3.he.net
> > [184.105.81.209]
> >
> >  9    75 ms    73 ms   102 ms  10ge15-6.core1.dal1.he.net
> > [184.105.222.10]
> >
> > 10    93 ms   103 ms    92 ms  eqix-da1.facebook.com [206.223.118.176]
> >
> > 11   102 ms   101 ms     *     psw01c.dfw1.tfbnw.net [173.252.65.196]
> >
> > 12    92 ms    97 ms   105 ms  msw1aq.01.dfw1.tfbnw.net [204.15.21.89]
> >
> > 13   110 ms     *       98 ms  instagram-p3-shv-01-dfw1.fbcdn.net
> > [31.13.66.52]
> >
> >
> >
> > Since I am peered with the route servers in EquinixIX Chicago,
> > shouldn't the data be coming from there, or at least hit their
> > routers?  In my trace, it shows HE to Chicago, then to Dallas.  How
> > does FB decide what IP the content gets displayed from, and is there
> > anything I can do as a provider?  If it is DNS, I can obviously clear
> > the cache to see if it gets new IPs.  If I'm not getting FB peering
> > IPs in Chicago, do I need to peer directly?  Should I get FaceBook involved?
> >
> >
> >
> > Eric Rogers
> >
> > PDS Connect
> >
> > (317) 831-3000 x200