[j-nsp] self-pointing route resolution: static vs. bgp ?

[Adam Vitkovsky]

Hi Alexandre,

Hmmm looks like you are trying to accomplish something fishy here :) (probably involving loopback right?)
Can you please expand on what your end goal is please, there might be some other way to skin the cat.

adam

>

        Adam Vitkovsky
        IP Engineer

T:      0333 006 5936
E:      Adam.Vitkovsky at gamma.co.uk
W:      www.gamma.co.uk

This is an email from Gamma Telecom Ltd, trading as “Gamma”. The contents of this email are confidential to the ordinary user of the email address to which it was addressed. This email is not intended to create any legal relationship. No one else may place any reliance upon it, or copy or forward all or any of it in any form (unless otherwise notified). If you receive this email in error, please accept our apologies, we would be obliged if you would telephone our postmaster on +44 (0) 808 178 9652 or email postmaster at gamma.co.uk

Gamma Telecom Limited, a company incorporated in England and Wales, with limited liability, with registered number 04340834, and whose registered office is at 5 Fleet Place London EC4M 7RD and whose principal place of business is at Kings House, Kings Road West, Newbury, Berkshire, RG14 5BY.


-----Original Message-----
> From: juniper-nsp [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf
> Of Alexandre Snarskii
> Sent: Thursday, October 22, 2015 6:30 PM
> To: juniper-nsp at puck.nether.net
> Subject: [j-nsp] self-pointing route resolution: static vs. bgp ?
>
>
> Hi!
>
> Imagine there is a directly connected network:
>
> A.B.C.40/29   *[Direct/0] 41w1d 00:10:40
>                     > via xe-0/0/2.232
>
> There is a good old trick: you can configure 'self-pointing'
> host route with next-hop within this network:
>
> snar at router> show configuration routing-options static route A.B.C.43/32
> next-hop A.B.C.43;
>
> it will be accepted, resolved and installed into routing table:
>
> snar at router> show route A.B.C.43/32 detail
>
> A.B.C.43/32 (1 entry, 1 announced)
>         State: <FlashAll>
>         *Static Preference: 5
>                 Next hop type: Router, Next hop index: 1256
>                 Address: 0x21a45c90
>                 Next-hop reference count: 5
>                 Next hop: A.B.C.43 via xe-0/0/2.232, selected
>
> (this trick was used before introduction vrf-table-label to install host routes in
> vrf's for customers who did not wanted to install CPE).
>
> However, when such self-pointing route is received over iBGP
>
> snar at router> show route A.B.C.42/32 receive-protocol bgp ...
>
>   A.B.C.42/32 (1 entry, 0 announced)
>      Accepted
>      Nexthop: A.B.C.42
>      MED: 100
>      Localpref: 20
>      AS path: I
>
> it becomes hidden with Unusable next-hop
>
> snar at router> show route A.B.C.42/32 hidden detail
>
> A.B.C.42/32 (1 entry, 0 announced)
>          BGP    Preference: 170/-21
>                 Next hop type: Unusable
>                 Address: 0x24e59bc
>                 Next-hop reference count: 3
>                 State: <Hidden Int Ext>
>                 Accepted
>                 Localpref: 15
>                 Indirect next hops: 1
>                         Protocol next hop: A.B.C.42
>                         Indirect next hop: 0 - INH Session ID: 0x0
>
>
> and not installed into forwarding table. Well, Juniper documentation clearly
> says[1] that it will not accept route pointing to device itself, but it is not the
> case, Local address is .41:
>
> A.B.C.41/32   *[Local/0] 44w0d 23:41:25
>                       Local via xe-0/0/2.232
>
>
> Question: are there any way to convince JunOS to resolve and install such
> self-pointing route when received over iBGP ?
>
> 12.3R5.7, MX80 if that matters.
>
> [1]:
> http://www.juniper.net/techpubs/en_US/junos13.3/topics/concept/hidden
> -routes-understanding.html
> Routes can be hidden for the following reasons:
> [...]
> The next hop address is the address of the local routing device.
>
> _______________________________________________
> juniper-nsp mailing list juniper-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/juniper-nsp