[j-nsp] cgnat on service module - interesting bgp advertisements

[Adam Vitkovsky]

> Alexander Arseniev
> Sent: Wednesday, April 20, 2016 7:36 AM
>
> Hello,
> MS-MIC (and MS-MPC NPUs as well) automatically cuts out network (in your
> case .128) and broadcast (in your case .255) IPs.
> The rest cannot be expressed as single prefix, hence a bunch of smaller
> prefixes is annonced instead.
> This was done as PR 1019354 fix
> https://prsearch.juniper.net/InfoCenter/index?page=prcontent&id=PR1019
> 354
Although I understand the part with omitting first and last address for NAT translations I don't understand the advertisement chopping part.

I'm just trying to think of a case where I'd define a NAT pool of 1.2.3.128/25 on the CG-NAT box and then use the 1.2.3.128 and 1.2.3.255 IPs somewhere else in the network so I would need the CG-NAT device to actually advertise just the IP ranges between 1.2.3.128 and 1.2.3.255 to avoid ...not sure what, as if I'd use and advertise the 1.2.3.128 and 1.2.3.255 as /32s they would still win over the 1.2.3.128/25 advertisement from CG-NAT box so no black holing or looping.

Anyways I assume one could hopefully summarize these back into /25 before the fragments are advertised to BGP peers right?

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.