Re: EVPN IRB - RFC 9135 support

[Ondrej Zajicek]

On Fri, Jul 12, 2024 at 03:01:53PM +0200, Erik Stomp wrote:
> Hi Maria,
> > Honestly, I'm now unaware of what is exactly supported as it's still in
> > development but Santiago should know, cc-ing him.
> Do you possibly cc-d the wrong person? I'm cc-ing Ondrej, as I think he is 
> the 
> right Santiago? :-)

Hi

This is me.


> If I don't miss anything, the current EVPN implementation does't support
> EVPN IRB as described in RFC 9135.
> 
> So my question is: Are there any plans to implement RFC 9135 in the
> foreseable future? I know, this isn't a 5 minute task and fully understand
> if it's not planned due to low priority.

This is not in our current plans for EVPN. I did not evaluate this RFC as it
was not necessary for the L2-only use cases that we considered.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santi...@crfreenet.org)
"To err is human -- to blame it on a computer is even more so."

Re: Limit of numbers of BGP communities

[Ondrej Zajicek]

On Fri, Jul 12, 2024 at 07:34:28AM +, Ponikierski, Grzegorz wrote:
> It assumes that Extended Length bit of Attribute Type is properly implemented 
> so community attribute can use attribute length field as 2 octet field, right?

Yes, that is a standard part of BGP.

> How situation changes with RFC 8654 - 
> Extended Message Support for BGP?

With that enabled on both sides, there is still 1 kB reserved for
prefixes, so you can have 63 kB for attributes, i.e. ~16128 standard,
~8064 extended, or ~5376 large communities. But propagation of such
route will break on the first non-RFC8654 session.

> On Fri, Jul 12, 2024 at 02:30:10AM +, Ponikierski, Grzegorz via 
> Bird-users wrote:
> Hello all!
> 
> How many standard communities, extended communities and large
> communities, user can apply on a route using Bird? BGP UPDATE message has
> finite size so I guess that there must be a limit somewhere.
> 
> Hello
> 
> There is no specific limit on communities, just a limit on overall BGP
> attribute length on export, which is 1 kB less than BGP message size
> (there is 1 kB reserved for prefixes). So with regular BGP messages,
> there can be at most 3 kB of attributes, which is ~768 standard, ~384
> extended, or ~256 large communities. In fact, it is a slightly less due
> to attribute framing and presence of other attributes than communities.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santi...@crfreenet.org)
"To err is human -- to blame it on a computer is even more so."

Re: EVPN IRB - RFC 9135 support

[Erik Stomp via Bird-users]

Hi Maria,
> Honestly, I'm now unaware of what is exactly supported as it's still in
> development but Santiago should know, cc-ing him.
Do you possibly cc-d the wrong person? I'm cc-ing Ondrej, as I think he is the 
right Santiago? :-)

> Basically the EVPN implementation depends on companies requesting this
> feature while having BIRD Support. This way, if you were into persuading
> your employer to migrate from FRR to BIRD …
> 
> … contact me off-list with more details and a quote for BIRD Support.
I would absolutely support that! But since we use FRR as a built-in part of 
SONiC / Dell FabricOS, unfortunately this is not really our choice as long as 
we use these switch operating systems.

> Have a nice weekend!
Thank you very much! Best wishes for a nice weekend from Germany!
Erik


-- 
OpenPGP Key-ID: 4AD5DF6F63FE15E5

signature.asc
Description: This is a digitally signed message part.

Re: Limit of numbers of BGP communities

[Jeroen Massar via Bird-users]

> On 12 Jul 2024, at 14:57, Douglas Fischer  wrote:
> 
> Unfortunately, this number of 100 BGP communities has no basis, at least not 
> yet, in the RFC.

A RFC is just a Request For Comments documents comments have been given 
amongst that in the form of the NLNOG BGP Filter Rules and other operators have 
also voiced their opinions, each network is their own.

There is also no BCP (Best Current Practice) document on this subject; nor a 
STD (Standard).

Operators can fortunately decide what they accept or not, own network, own 
rules, bit the point of an Autonomous System.

> It is just a recommendation (a very healthy one, by the way) from the NLNOG 
> team.
> 
> As far as I remember, neither the maximum mask limit of /24 for IPv4 nor /48 
> for IPv6 in a BGP session are defined in RFC as either must or should.
> 
> It would be good if it were in the RFCs, but it is not.

In a way, all the NLNOG BGP Filter Rules are effectively a BCP, it is just not 
a document that went through the IETF process.

As it is a changing target, unlikely that a IETF BCP makes sense either IMHO.

Greets,
 Jeroen

Re: Limit of numbers of BGP communities

[Douglas Fischer]

Unfortunately, this number of 100 BGP communities has no basis, at least
not yet, in the RFC.
It is just a recommendation (a very healthy one, by the way) from the NLNOG
team.

As far as I remember, neither the maximum mask limit of /24 for IPv4 nor
/48 for IPv6 in a BGP session are defined in RFC as either must or should.

It would be good if it were in the RFCs, but it is not.

Em sex., 12 de jul. de 2024 às 06:43, Jeroen Massar via Bird-users <
bird-users@network.cz> escreveu:

>
>
> > On 12 Jul 2024, at 04:30, Ponikierski, Grzegorz via Bird-users <
> bird-users@network.cz> wrote:
> >
> > Hello all!
> >  How many standard communities, extended communities and large
> communities, user can apply on a route using Bird? BGP UPDATE message has
> finite size so I guess that there must be a limit somewhere.
>
> The limit is that ISPs are limiting it to a 100:
>
>  https://bgpfilterguide.nlnog.net/guides/many_communities/
>
> Above that, it will be emptied completely in many networks.
>
> Greets,
>  Jeroen
>
>
>
>

-- 
Douglas Fernando Fischer
Engº de Controle e Automação

Re: EVPN IRB - RFC 9135 support

[Maria Matejka via Bird-users]

Hello Erik,

On Fri, Jul 12, 2024 at 01:30:06PM +0200, Erik Stomp via Bird-users wrote:

> If I don't miss anything, the current EVPN implementation does't support
> EVPN IRB as described in RFC 9135.
> Since I only want to use BIRD EVPN in a lab, this is not a big problem for
> me. Of course I could use FRR, which supports IRB, but since I use BIRD
> everywhere, it would be nice if I could also use it in the EVPN lab.

Honestly, I'm now unaware of what is exactly supported as it's still in
development but Santiago should know, cc-ing him.

> So my question is: Are there any plans to implement RFC 9135 in the
> foreseable future? I know, this isn't a 5 minute task and fully understand
> if it's not planned due to low priority.

Basically the EVPN implementation depends on companies requesting this
feature while having BIRD Support. This way, if you were into persuading
your employer to migrate from FRR to BIRD …

… contact me off-list with more details and a quote for BIRD Support.

Have a nice weekend! 
Maria

-- 
Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.

EVPN IRB - RFC 9135 support

[Erik Stomp via Bird-users]

Dear BIRD community,

I plan to use the BIRD EVPN beta implementation 
(https://gitlab.nic.cz/labs/bird/-/tree/evpn?ref_type=heads) for a 
private Lab.
I use EVPN in my employer's data center (based on FRR), so I am already 
quite familiar with EVPN.


If I don't miss anything, the current EVPN implementation does't support 
EVPN IRB as described in RFC 9135.
Since I only want to use BIRD EVPN in a lab, this is not a big problem 
for me. Of course I could use FRR, which supports IRB, but since I use 
BIRD everywhere, it would be nice if I could also use it in the EVPN 
lab.


So my question is: Are there any plans to implement RFC 9135 in the 
foreseable future? I know, this isn't a 5 minute task and fully 
understand if it's not planned due to low priority.
Maybe I can use the new L3VPN feature as an alternative then. Has anyone 
tried it yet? Otherwise, I'll have a look at it, as soon as I find some 
time.


Best regards,
Erik

Re: Limit of numbers of BGP communities

[Jeroen Massar via Bird-users]

> On 12 Jul 2024, at 04:30, Ponikierski, Grzegorz via Bird-users 
>  wrote:
> 
> Hello all!
>  How many standard communities, extended communities and large communities, 
> user can apply on a route using Bird? BGP UPDATE message has finite size so I 
> guess that there must be a limit somewhere.

The limit is that ISPs are limiting it to a 100:

 https://bgpfilterguide.nlnog.net/guides/many_communities/

Above that, it will be emptied completely in many networks.

Greets,
 Jeroen

Re: Limit of numbers of BGP communities

[Ponikierski, Grzegorz via Bird-users]

It assumes that Extended Length bit of Attribute Type is properly implemented 
so community attribute can use attribute length field as 2 octet field, right?

How situation changes with RFC 8654 - 
Extended Message Support for BGP?

Regards,
Grzegorz

From: Ondrej Zajicek 
Date: Friday, 12 July 2024 at 05:40
To: "Ponikierski, Grzegorz" 
Cc: "bird-users@network.cz" 
Subject: Re: Limit of numbers of BGP communities

On Fri, Jul 12, 2024 at 02:30:10AM +, Ponikierski, Grzegorz via Bird-users 
wrote:
Hello all!

How many standard communities, extended communities and large
communities, user can apply on a route using Bird? BGP UPDATE message has
finite size so I guess that there must be a limit somewhere.

Hello

There is no specific limit on communities, just a limit on overall BGP
attribute length on export, which is 1 kB less than BGP message size
(there is 1 kB reserved for prefixes). So with regular BGP messages,
there can be at most 3 kB of attributes, which is ~768 standard, ~384
extended, or ~256 large communities. In fact, it is a slightly less due
to attribute framing and presence of other attributes than communities.

--
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: 
santi...@crfreenet.org)
"To err is human -- to blame it on a computer is even more so."