Re: [j-nsp] MX204 and IPv6 BGP announcements

[Lee Starnes via juniper-nsp]

All very good information. Thanks guys for all the replies. very helpful.

On Thu, Feb 8, 2024 at 6:42 AM Mark Tinka  wrote:

>
>
> On 2/8/24 16:29, Saku Ytti wrote:
>
> In absence of more specifics, junos by default doesn't discard but
> reject.
>
>
> Right, which I wanted to clarify if it does the same thing with this
> specific feature, or if it does "discard"
>
> Mark.
>
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Re: [j-nsp] MX204 and IPv6 BGP announcements

[Mark Tinka via juniper-nsp]

On 2/8/24 16:29, Saku Ytti wrote:


In absence of more specifics, junos by default doesn't discard but
reject.


Right, which I wanted to clarify if it does the same thing with this 
specific feature, or if it does "discard"


Mark.
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Re: [j-nsp] MX204 and IPv6 BGP announcements

[Saku Ytti via juniper-nsp]

On Thu, 8 Feb 2024 at 16:07, Mark Tinka via juniper-nsp
 wrote:

> So internally, if it attracts any traffic for non-specific destinations,
> does Junos send it /dev/null in hardware? I'd guess so...

In absence of more specifics, junos by default doesn't discard but
reject. There is essentially implied 0/0 static route to reject
adjacency. This can be changed to be discard, or you can just nail
down default discard.


-- 
  ++ytti
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Re: [j-nsp] MX204 and IPv6 BGP announcements

[Jeff Haas via juniper-nsp]

Correcting myself, yes, it’s discard.

-- Jeff




Juniper Business Use Only
From: Mark Tinka 
Date: Thursday, February 8, 2024 at 9:07 AM
To: Jeff Haas , Lee Starnes , 
"juniper-nsp@puck.nether.net" 
Subject: Re: [j-nsp] MX204 and IPv6 BGP announcements

[External Email. Be cautious of content]


On 2/8/24 15:48, Jeff Haas wrote:
It’s rib-only.  If you wanted the usual other properties, you’d use the usual 
other features.

So internally, if it attracts any traffic for non-specific destinations, does 
Junos send it /dev/null in hardware? I'd guess so...

Mark.
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Re: [j-nsp] MX204 and IPv6 BGP announcements

[Mark Tinka via juniper-nsp]

On 2/8/24 15:48, Jeff Haas wrote:

It’s rib-only.  If you wanted the usual other properties, you’d use 
the usual other features.




So internally, if it attracts any traffic for non-specific destinations, 
does Junos send it /dev/null in hardware? I'd guess so...


Mark.
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Re: [j-nsp] MX204 and IPv6 BGP announcements

[Jeff Haas via juniper-nsp]

It’s rib-only.  If you wanted the usual other properties, you’d use the usual 
other features.

-- Jeff




Juniper Business Use Only
From: Mark Tinka 
Date: Thursday, February 8, 2024 at 12:14 AM
To: Jeff Haas , Lee Starnes , 
"juniper-nsp@puck.nether.net" 
Subject: Re: [j-nsp] MX204 and IPv6 BGP announcements

[External Email. Be cautious of content]


On 2/6/24 19:42, Jeff Haas wrote:



And for situations where you need it nailed up:



https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/bgp-static-edit-routing-options.html

Interesting, never knew about this BGP-specific feature.

What does the router do with this in FIB? Same as a a regular static route 
pointing to 'discard'? Or does it just stay in RIB?

Mark.
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Re: [j-nsp] MX204 and IPv6 BGP announcements

[Mark Tinka via juniper-nsp]

On 2/6/24 19:42, Jeff Haas wrote:


And for situations where you need it nailed up:

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/bgp-static-edit-routing-options.html


Interesting, never knew about this BGP-specific feature.

What does the router do with this in FIB? Same as a a regular static 
route pointing to 'discard'? Or does it just stay in RIB?


Mark.
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Re: [j-nsp] MX204 and IPv6 BGP announcements

[Jeff Haas via juniper-nsp]

On 2/6/24, 11:55 AM, "juniper-nsp on behalf of Mark Tinka via juniper-nsp" 
mailto:juniper-nsp-boun...@puck.nether.net> on behalf of 
juniper-nsp@puck.nether.net > wrote:
> Typically, BGP will not originate a route to its neighbors unless it
> already exists in the routing table through some source. If it is an
> aggregate route, a hold-down pointing to "discard" (Null0 in Cisco) is
> enough. If it is a longer route assigned to a customer, that route
> pointing to the customer will do.

And for situations where you need it nailed up:

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/bgp-static-edit-routing-options.html


Juniper Business Use Only
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Re: [j-nsp] MX204 and IPv6 BGP announcements

[Lee Starnes via juniper-nsp]

Thanks Mark for the quick reply. That was the validation I was looking for.
The TAC tech was really unsure about what he was doing and I had to guide
him through things, So this is very helpful.

Thanks again.

-Lee


On Tue, Feb 6, 2024 at 8:54 AM Mark Tinka  wrote:

>
>
> On 2/6/24 18:48, Lee Starnes via juniper-nsp wrote:
>
> > Hello everyone,
> >
> > I was having difficulty in getting an announcement of a IPv6 /32 block
> > using prefix-lists rather than redistribution of the IP addresses in from
> > other protocols. We only have a couple /64 blocks in use at the moment
> but
> > want to be able to announce the entire /32. In cisco, that would just be
> a
> > holddown route and then announce. Not sure how it works to Juniper.
> >
> > I configured a prefix-list that contained the /32 block in it. Then
> created
> > a policy statement with term 1 from prefix-list  and then term 2
> then
> > accept. Set the export in BGP protocol peer of this policy statement and
> it
> > just ignores it.
> >
> > Now this same setup in IPv4 works fine.
> >
> > After a week of going round and round with Juniper TAC, they had me
> setup a
> > rib inet6 aggregate entry for the /32 and then use that in the policy
> > statement.
>
> This is the equivalent of the "hold-down" route you refer to in
> Cisco-land. Useful if the route does not exist in the RIB from any other
> source.
>
> I'm guessing your IPv4 route just works without a hold-down route
> because it is being learned from somewhere else (perhaps your IGP, iBGP
> or a static route), and as such, already exists in the router's RIB for
> your export policy to pick it up with no additional fiddling.
>
> Typically, BGP will not originate a route to its neighbors unless it
> already exists in the routing table through some source. If it is an
> aggregate route, a hold-down pointing to "discard" (Null0 in Cisco) is
> enough. If it is a longer route assigned to a customer, that route
> pointing to the customer will do.
>
> Mark.
>
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Re: [j-nsp] MX204 and IPv6 BGP announcements

[Mark Tinka via juniper-nsp]

On 2/6/24 18:48, Lee Starnes via juniper-nsp wrote:


Hello everyone,

I was having difficulty in getting an announcement of a IPv6 /32 block
using prefix-lists rather than redistribution of the IP addresses in from
other protocols. We only have a couple /64 blocks in use at the moment but
want to be able to announce the entire /32. In cisco, that would just be a
holddown route and then announce. Not sure how it works to Juniper.

I configured a prefix-list that contained the /32 block in it. Then created
a policy statement with term 1 from prefix-list  and then term 2 then
accept. Set the export in BGP protocol peer of this policy statement and it
just ignores it.

Now this same setup in IPv4 works fine.

After a week of going round and round with Juniper TAC, they had me setup a
rib inet6 aggregate entry for the /32 and then use that in the policy
statement.


This is the equivalent of the "hold-down" route you refer to in 
Cisco-land. Useful if the route does not exist in the RIB from any other 
source.


I'm guessing your IPv4 route just works without a hold-down route 
because it is being learned from somewhere else (perhaps your IGP, iBGP 
or a static route), and as such, already exists in the router's RIB for 
your export policy to pick it up with no additional fiddling.


Typically, BGP will not originate a route to its neighbors unless it 
already exists in the routing table through some source. If it is an 
aggregate route, a hold-down pointing to "discard" (Null0 in Cisco) is 
enough. If it is a longer route assigned to a customer, that route 
pointing to the customer will do.


Mark.
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