Re: asymmetric routing

Thanks for sharing :)

On Friday, March 1, 2013, Tony Singh wrote:

>
>
> fixed by changing to the same cluster-id on both RR's, I was reading that
> using a different cluster-id's would avoid corner case black holing of
> traffic hence my reason to use it.
>
> come in Mr McGahan
>
> :0)
>
>
> On 2 March 2013 03:32, Tony Singh <mothafungla_at_gmail.com> wrote:
>
>
>
> Hi Marc
>
> Thanks yes because firewall see's half conversation it is dropping traffic.
>
> Ok what I'm seeing on my RR is this
>
> SW1 clients are CE1 & SW2
> SW2 clients are CE2 & SW1
>
> So in the bgp rib of both reflectors I'm seeing SW1 not seeing CE2 as a
> valid path until the CE1>PE1 link drops
>
> SW2 however is seeing both CE2 (local) & CE1's addresses as bgp valid rib
> paths to the learnt source prefixes herin lies the problem
>
> Is my RR design correct? I am using different cluster-id's within same AS,
> but SW1 has it nailed on as in "I don't want to see the CE2 path as valid
> until my CE1>PE1 link drops"
>
>
> Tony
>
>
> On 2 March 2013 03:24, marc edwards <renorider_at_gmail.com> wrote:
>
> So I have have a few thoughts on this...
>
> First, is it causing a problem (bandwidth congestion, added latency,
> etc...) requiring fixing? Asymmetric routing can exist without harming
> traffic (i.e. the Internet)
>
> Second, I thought about a fix. Since issue originates upstream I think
> you will need to work with SP to possibly tag or send community valus
> on upstream devices that can help identify where traffic is
> originating and using these characteristics to filter.
>
> HTH
>
> Marc Edwards
> CCIE #38259
>
>
> On Fri, Mar 1, 2013 at 6:56 PM, Tony Singh <mothafungla_at_gmail.com> wrote:
> > Hi Marc
> >
> > Its is one AS bro, im stumped a bit here...
> >
> > Say that same source gets to a subnet behind CE1 and everything works
> fine
> > on this inbound-to-outbound path then the same source decides to reach a
> > subnet behind CE2 where inbound everything is ok but outbound for the CE2
> > originating subnet it prefers CE1 due to best path selection 11 lowest
> > router-id..
> >
> > Now if I knew the source prefix I would create a standard ACL and route
> map
> > to achieve the desired goal, I'm sure I can figure this out with some
> help
> > :0)
> >
> >
> > Tony
> >
> >
> > On 2 March 2013 02:40, marc abel <marcabel_at_gmail.com> wrote:
> >
> >>
> >> Is it one provider or 2? Can you do As path prepending?
> >>
> >>
> >> On Fri, Mar 1, 2013 at 8:23 PM, Tony Singh <mothafungla_at_gmail.com>
> wrote:
> >>
> >>> Hi Experts
> >>>
> >>> Just like to gauge what would you do on best practice if we have the
> >>> following scenario
> >>>
> >>> PE1>CE1>FW>SW>trunk>SW>FW>CE2>PE2
> >>>
> >>> SW's are RR
> >>>
> >>> traffic inbound to particular subnets is influenced by outbound
> policies
> >>> on
> >>> the MED attribute, but my problem is when routing outbound the lowest
> >>> router-id of CE1 wins when the packet originated from CE2
> >>>
> >>> Now "when you do not know" what the out-to-in source prefixes will be,
> >>> then
> >>> what is the best design practice you would follow?
> >>>
> >>> BR
> >>>
> >>> Tony
> >>>
> >>>
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> >>
> >>
> >> --
> >
>
>

-- 
Marc Edwards - CCIE #38259
Blogs and organic groups at http://www.ccie.net