[AusNOG] Megaport IX Sydney - Sudden grows in number of prefixes

Fri Jan 12 09:30:07 EST 2018

If you want to force routing to go a particular way, there is only one sure-fire way to do that… advertise smaller subnets via your preferred path.

From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Philip Loenneker
Sent: Friday, 12 January 2018 9:17 AM
To: McDonald Richards <mcdonald.richards at gmail.com>; ausnog at lists.ausnog.net
Subject: Re: [AusNOG] Megaport IX Sydney - Sudden grows in number of prefixes

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I was referring to the BGP route selection rules. But as someone else pointed out, there are things like local pref that they can use, which falls within those rules…

From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of McDonald Richards
Sent: Friday, 12 January 2018 9:14 AM
To: ausnog at lists.ausnog.net
Subject: Re: [AusNOG] Megaport IX Sydney - Sudden grows in number of prefixes

Pretty sure there are no rules....

On Fri, Jan 12, 2018 at 9:08 AM, Philip Loenneker <Philip.Loenneker at tasmanet.com.au<mailto:Philip.Loenneker at tasmanet.com.au>> wrote:
Traffic engineering is difficult when people don’t play by the rules…

Perhaps using the HE community strings which Jacob suggested would be more helpful – you may be able to prevent HE advertising your subnets to TPG. Unless NSW-IX remove all community strings when they go to peers….

From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net<mailto:ausnog-bounces at lists.ausnog.net>] On Behalf Of John Alexander
Sent: Friday, 12 January 2018 9:04 AM
To: ausnog at lists.ausnog.net<mailto:ausnog at lists.ausnog.net>

Subject: Re: [AusNOG] Megaport IX Sydney - Sudden grows in number of prefixes

I tried this, with 3:6939 which added 3 prepends to he (which I could see at HE's LG) but TPG still preferred to send traffic via he rather than transit, even though the path was longer...

ughhh

On 01/12/2018 08:52 AM, Philip Loenneker wrote:

Note that you can also use BGP communities to adjust how the IX advertises your subnets to individual peers using the documentation here:

https://www.ix.asn.au/peering-technical/

Unfortunately you can't set a community of 0:7545 to avoid advertising your routes to TPG, as they aren't the direct peer - you would need to block advertising to HE using 0:6427. It may be sufficient for you to prepend the routes being advertised to HE, using 3:6427, to reduce the amount of traffic taking that path, but still keeping it available.

-----Original Message-----

From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Bill Walker

Sent: Friday, 12 January 2018 8:11 AM

To: John Alexander <johna at wideband.net.au><mailto:johna at wideband.net.au>

Cc: ausnog at lists.ausnog.net<mailto:ausnog at lists.ausnog.net>

Subject: Re: [AusNOG] Megaport IX Sydney - Sudden grows in number of prefixes

Filter based on the AS Path?

If the path is:

You <- 58941 <- 6427 <- 7545

You <- MegaIXSyd <- HE <- TPG

In the Cisco world, I would use

ip as-path access-list 10 deny ^58941_6427_7545$

(The ASN's here may not be exactly what is in use, you will need to check your received prefixes)

On 2018-01-12 09:46, John Alexander wrote:

With this, does anyone know of a way of keeping HE routes, but

excluding a specific one, namely TPG 7545 which is a direct customer

of HE. Traffic from them goes from Syd -> LA -> Syd -> he peering ->

me.  I'd prefer to just make them stay at home so to speak instead of

going around the world.  We don't peer at Pipe which would be the only

other place to connect to tpg.

John

On 01/11/2018 05:55 PM, Nathan Le Nevez wrote:

I assume it was Hurricane Electric...IPv6 routes are now at 21843 too

Nathan

-----Original Message-----

From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of

Paul Holmanskikh

Sent: Thursday, 11 January 2018 5:00 PM

To: ausnog at lists.ausnog.net<mailto:ausnog at lists.ausnog.net>

Subject: [AusNOG] Megaport IX Sydney - Sudden grows in number of

prefixes

G'day,

Number of prefixes we are receiving from Megaport IX in Sydeney

suddenly jumped to 40493.

At lest 100% grow.  Any ideas what happened.

as_path    count

36351    945

4739    909

9443    658

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