SingTel (AS7473) is only announcing ConnectPlus (AS9911) routes to Level3 (AS3356) in SJC?

Adam LaFountain adam.lafountain at googlemail.com
Thu Aug 5 02:06:27 CDT 2010


> Date: Fri, 30 Jul 2010 17:38:55 +0200
> From: Martin Barry <marty at supine.com>
> Subject: SingTel (AS7473) is only announcing ConnectPlus (AS9911)
>        routes to       Level3 (AS3356) in SJC?
> To: nanog at nanog.org
>
> Anyone on the list who can offer an explanation about the following
> scenario? We have taken this up with providers at either end but it
> will take awhile to filter up to the ASes in question.
>
> We were seeing a London to Singapore connection go via San Jose
> causing a 50%+ increase in latency.
>
> It appears that SingTel (AS7473) is only announcing ConnectPlus
> (AS9911) routes to Level3 (AS3356) in SJC.
>
> However they have many adjacencies in many countries and other routes
> of both AS7473 and it's other downstreams don't appear to be affected
> (although I haven't tested them all).
>
> Traceroutes are appended at the end but to see for yourself use
> 202.176.222.0 as a BGP or traceroute query in the Level3 looking glass
> for both London and any other location, then compare with 167.172.93.0
>
> Checking another large AS at random, they see AS7473 announcing AS9911
> routes in London.
>
> thanks
> Marty

At first I wanted to say this looks like a policy move on 7473's part
but on further investigation I'm not sure if they're punishing
themselves or doing some very specific traffic routing possible for
balancing purposes.  Noticing in Leve'3 bgp output they're a customer

 Show Level 3 (London, England) BGP routes for 202.176.222.212

BGP routing table entry for 202.176.222.0/24
Paths: (2 available, best #1)
  7473 9911
  AS-path translation: { APNIC-AS-2-BLOCK APNIC-AS-3-BLOCK }
    car2.SanJose1 (metric 44128)
      Origin IGP, metric 100, localpref 100, valid, internal, best
      Community: North_America  Lclprf_100 Level3_Customer
United_States San_Jose 7473:10000 7473:20000 7473:41101
Prepend_2_to_AS1668 Prepend_2_to_AS13680
      Originator: car2.SanJose1
  7473 9911
  AS-path translation: { APNIC-AS-2-BLOCK APNIC-AS-3-BLOCK }
    car2.SanJose1 (metric 44128)
      Origin IGP, metric 100, localpref 100, valid, internal
      Community: North_America  Lclprf_100 Level3_Customer
United_States San_Jose 7473:10000 7473:20000 7473:41101
Prepend_2_to_AS1668 Prepend_2_to_AS13680
      Originator: car2.SanJose1

I was inclined to believe it was related to cost, especially seeing
the prepend for AOL (1668), but began to dimiss that as I saw two
known _peers_ haul the traffic to the west coast as well:

Router: gin-l78-mcore3
Site: GB, London - L78, VSNL LONTX01 STRATFORD
Command: show ip bgp 202.176.222.212


BGP routing table entry for 202.176.222.0/24
Bestpath Modifiers: deterministic-med
Paths: (3 available, best #2)
     13         16
  7473 9911
    laa-icore1. (metric 3100) from laa-mcore3. (laa-mcore3.)
      Origin IGP, valid, internal
      Community: Peer route North America West Coast Los Angeles (LAA, LMR)
      Originator: laa-icore1.
  7473 9911
    pdi-icore1. (metric 3095) from pdi-mcore4. (pdi-mcore4.)
      Origin IGP, valid, internal, best
      Community: Peer route North America West Coast Palo Alto (PDI)
      Originator: pdi-icore1.

and-
1	74 ms	75 ms	75 ms	10gigabitethernet2-3.core1.nyc4.he.net (72.52.92.77)
2	130 ms	149 ms	147 ms	10gigabitethernet5-3.core1.lax1.he.net (72.52.92.226)
3	131 ms	130 ms	139 ms	laxeq-ds2-peer1.singtel.com (206.223.123.120)
4	131 ms	130 ms	139 ms	ge-1-0-0-0.laxow-cr2.ix.singtel.com (203.208.149.118)

In terms of figuring it out for sure I dont think L3 will tell you
anything as they probably don't know.  SingTel's your best bet but
good luck with that unless you become a customer.  I'm going to vote
backbone traffic balancing by SingTel.




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