Question on routing of Tata AS6453 with their other network AS4755

Sat Nov 16 20:24:55 UTC 2013

We have a ticket open with Tata currently on a similar issue. 

Traffic from our AS (51088) via Tata to DTAG goes from Amsterdam, NL, to Tata Frankfurth, Germany, to Tata Paris, France, to DTAG In Paris, back to Germany ?? With packetloss... 

Our Tinet (GT-T) routes go from Amsterdam to DTAG ( Amsterdam) to Germany .. 

No reply on the ticket yet where the packetloss comes from or why they are routing via Paris which adds about 30 ms ...

Check out our Smokeping page for it .. 

http://smokeping.a2b-internet.com/smokeping/smokeping.cgi?target=LatencyCheckList.Tata_Paris

We are currently pref'ing the traffic to DTAG via Tinet/ GT-T. 

Erik Bais
A2B Internet 

Verstuurd vanaf mijn iPad

Op 16 nov. 2013 om 20:49 heeft Anurag Bhatia <me at anuragbhatia.com> het volgende geschreven:

> Hello everyone
> 
> 
> I was looking around and noticed a pretty bad route from DTAG to Tata
> AS6453 (basically destination was Tata Comm's Indian network on AS4755). I
> am not able to understand cause for inefficient routing but I am sure I am
> failing to understand something which is crazy in their IGP. The result is
> that route from Europe to India is via Europe > US > Singapore > India
> rather then direct India.
> 
> There seem to be quite a few prefixes with these problem, but for this mail
> question, I am picking two prefixes - one which seems to be having good
> routing.
> 
> 202.54.82.0/24 has pretty bad routing while 93.183.28.0/24. I see both
> prefixes have valid route objects and are originated by VSNL AS4755 to Tata
> AS6453 in India. Now if we compare trace from Tata's own core router say in
> Paris from their looking glass, I get:
> 
> 
> Router: gin-pye-core1
> Site: FR, Paris, PYE
> Command: traceroute ip 202.54.82.1
> 
> Tracing the route to RAS55.1.ppppun.vsnl.net.in (202.54.82.1)
> 
>  1 if-1-0-0-2.tcore1.PYE-Paris.as6453.net (80.231.154.45) [MPLS: Label
> 525297 Exp 0] 300 msec
>    if-0-0-0-0.tcore1.PYE-Paris.as6453.net (80.231.154.37) [MPLS: Label
> 525297 Exp 0] 260 msec
>    if-1-0-0-2.tcore1.PYE-Paris.as6453.net (80.231.154.45) [MPLS: Label
> 525297 Exp 0] 260 msec
>  2 if-5-2.tcore1.L78-London.as6453.net (80.231.130.1) [MPLS: Label 523604
> Exp 0] 264 msec
>    if-3-6.tcore1.L78-London.as6453.net (80.231.130.85) [MPLS: Label 523604
> Exp 0] 256 msec
>    if-5-2.tcore1.L78-London.as6453.net (80.231.130.1) [MPLS: Label 523604
> Exp 0] 264 msec
>  3 if-2-2.tcore2.L78-London.as6453.net (80.231.131.1) [MPLS: Label 728466
> Exp 0] 264 msec
>  *  if-1-2.tcore2.L78-London.as6453.net
> <http://if-1-2.tcore2.L78-London.as6453.net> (80.231.130.122) [MPLS: Label
> 728466 Exp 0] 264 msec 268 msec*
> *  4 if-20-2.tcore2.NYY-NewYork.as6453.net
> <http://if-20-2.tcore2.NYY-NewYork.as6453.net> (216.6.99.13) [MPLS: Label
> 354225 Exp 0] 276 msec 260 msec 260 msec*
>  5  *
>    if-12-6.tcore1.CT8-Chicago.as6453.net (216.6.99.46) [MPLS: Label 365409
> Exp 0] 304 msec
>    if-11-2.tcore1.NYY-NewYork.as6453.net (216.6.99.2) [MPLS: Label 782881
> Exp 0] 256 msec
>  6 if-22-2.tcore2.CT8-Chicago.as6453.net (64.86.79.1) [MPLS: Label 361921
> Exp 0] 264 msec 264 msec
>    if-1-2.tcore1.PDI-PaloAlto.as6453.net (66.198.127.5) [MPLS: Label
> 670352 Exp 0] 256 msec
>  7 if-11-3.tcore2.PDI-PaloAlto.as6453.net (66.198.144.57) [MPLS: Label
> 321233 Exp 0] 256 msec
>    if-2-2.tcore2.PDI-PaloAlto.as6453.net (66.198.127.2) [MPLS: Label
> 321233 Exp 0] 260 msec *
>  8 if-9-2.tcore1.TV2-Tokyo.as6453.net (180.87.180.18) 280 msec 260 msec
> 260 msec
>  9 if-2-2.tcore2.TV2-Tokyo.as6453.net (180.87.180.2) [MPLS: Label 581761
> Exp 0] 252 msec 252 msec 252 msec
> 10 if-6-2.tcore1.SVW-Singapore.as6453.net (180.87.12.109) [MPLS: Label
> 710034 Exp 0] 248 msec 244 msec 248 msec
> 11 if-5-2.tcore1.CXR-Chennai.as6453.net (180.87.12.54) 244 msec 272 msec
> 252 msec
> 12 180.87.36.10 272 msec 256 msec 272 msec
> 13 172.31.19.94 272 msec 252 msec 256 msec
> 14  *  *
>    172.25.83.142 288 msec
> 15 172.25.83.134 !H  *  *
> 
> 
> while for other prefix, route is:
> 
> Router: gin-pye-core1
> Site: FR, Paris, PYE
> Command: traceroute ip 93.183.28.1
> 
> Tracing the route to 93.183.28.1
> 
>  1 if-1-0-0-2.tcore1.PYE-Paris.as6453.net (80.231.154.45) [MPLS: Label
> 519713 Exp 0] 12 msec
>    if-0-0-0-0.tcore1.PYE-Paris.as6453.net (80.231.154.37) [MPLS: Label
> 519713 Exp 0] 12 msec
>    if-1-0-0-2.tcore1.PYE-Paris.as6453.net (80.231.154.45) [MPLS: Label
> 519713 Exp 0] 12 msec
>  2 if-8-1600.tcore1.WYN-Marseille.as6453.net (80.231.217.5) [MPLS: Label
> 302880 Exp 0] 12 msec
>    if-14-2.tcore1.WYN-Marseille.as6453.net (80.231.154.170) [MPLS: Label
> 302880 Exp 0] 36 msec
>    if-8-1600.tcore1.WYN-Marseille.as6453.net (80.231.217.5) [MPLS: Label
> 302880 Exp 0] 12 msec
>  *3 if-2-2.tcore2.WYN-Marseille.as6453.net
> <http://if-2-2.tcore2.WYN-Marseille.as6453.net> (80.231.217.2) 12 msec 12
> msec 12 msec*
>  4 80.231.200.26 140 msec 116 msec 116 msec
>  5 172.31.16.193 148 msec 140 msec 144 msec
> * 6 115.114.71.133.static-chennai.vsnl.net.in
> <http://115.114.71.133.static-chennai.vsnl.net.in> (115.114.71.133) [AS
> 4755] 140 msec 148 msec 140 msec*
>  7 172.29.209.82 [MPLS: Labels 301664/7167 Exp 1] 148 msec 144 msec 148
> msec
>  8 172.31.35.138 [MPLS: Labels 4831/7167 Exp 1] 152 msec 152 msec 148 msec
>  9 121.242.126.205.static-chennai.vsnl.net.in (121.242.126.205) [AS 4755]
> [MPLS: Label 7167 Exp 1] 148 msec *  140 msec
> 10 121.242.126.206.static-chennai.vsnl.net.in (121.242.126.206) [AS 4755]
> 140 msec 148 msec 140 msec
> 11  *  *  *
> 12  *  *  *
> 
> 
> 
> Now if I focus on best route entry in router for both prefixes, I see
> following:
> 
> Bad Prefix:
> 4755
>    tv2-tcore1. (metric 16148) from *hk2-core3.* (hk2-core3.)
>      Origin IGP, valid, internal, best
>      Community:
>      Originator: 66.110.10.113
> 
> 
> Good Prefix:
> 4755
>    wyn-tcore2. (metric 10050) *from wyn-tcore2.* (66.110.10.109)
>      Origin IGP, valid, internal, best
>      Community:
> 
> 
> 
> 
> Now as I understand Paris router is getting bad prefix from TV2 which is
> their Tokyo router while for other prefix with good routing, route is via
> their other router on cable landing station in France.
> 
> Can someone explain me what exactly is happening here? Are they missing
> some iBGP sessions?  It's not perfect mesh & missing route reflectors?
> 
> Probably both prefixes are originated inside India by different routers but
> as I understand all prefixes get transit from AS6453 and so is it like
> AS6453 missing some routes (which seem to be direct) to technically
> downstream AS4755?
> 
> 
> Curious to hear your thoughts.
> 
> 
> Note: I am not worried about issue - it's not really impacting me. Just
> trying to learn what is wrong in the backbone design here.
> 
> 
> 
> 
> Thanks.
> -- 
> 
> 
> Anurag Bhatia
> anuragbhatia.com
> 
> Linkedin <http://in.linkedin.com/in/anuragbhatia21> |
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