Re: [spring] Beyond SRv6.

[松嶋聡 <[e-mail]>]

As an operator of running a nation wide network in non-trivial size with
SRv6, I agree on that multiple or many SRv6 SIDs support in terms of MTU
size limit is not an issue.

And solutions already exist that enable us to deploy TE with minimum number
of SID (e.g, flex-algo) not only for SRv6, but also for SR-MPLS. Additional
solution to reduce size of SIDs seems beneficial. However, requiring
another type of EH just for reduce the size of SIDs sounds no make sense to
me.

Therefore I see no benefits on CRH for our deployments. SRH has been
developed and specified through legitimate IETF process with non-trivial
time and efforts. Adding extra header for the same purpose would waste all
our precious efforts so far and require much unnecessary time and efforts
down the load which is no make sense for all of us.

We have to stick SRH to be used and be compatible with the existing SID
definition in SRH if we need solution to reduce SIDs.

Cheers,
--satoru

2019/09/08 16:19、Gyan Mishra <[e-mail]>のメール:

As an operator of a Tier 1 provider with massive mpls networks I think our
traditional bread and butter “mpls” will be around for a very very long
time as is IPv4 if not longer.

Most all service provider cores run greater then or equal to MTU 9000 mpls
cores to account for mpls overhead shims being tacked on plus edge overhead
from possible GRE tunneling or IPSEC so in general making  the core the
maximum Jumbo MTU supported by most vendors at 9216 is what is generally
done out in the field.

So for SRv6 support of multiple or many EH insertions is really a non issue
for
most operators.

>From reading through all the discussion threads the SR insertion is two
fold one being for FRR capabilities using Ti-LFA or remote LFA tunnel so
end up requiring double EH insertions on the Ingress PE tunnel head end
SRv6 source node and then second scenario being a possible EH insertions
occurrence on intermediate nodes.  I have not read through the drafts or
RFC regarding Ti-LFA with SR but since that is an IGP extension I am
guessing an opaque LSA and is not the traditional MPLS FRR link/node/path
protection that adds an additional mpls shim so not sure why an EH
insertion needs to occur for Ti-LFA.  Can someone clarify that use case for
me.  Also the EH insertion on intermediate node what is the use case or
reason for that.  My guess is it’s for special use case of stitching SRv6
domains together.  Please clarify..

I do agree with some of the other operators on the marketing hype and push
for SR-MPLS and SRv6 is not for every service provider as goes the mantra
..”if it’s not broken..don’t try to fix it..leave it alone” and I think you
can definitely say that for MPLS as it has had a SOLID run for service
providers since the 90’s ever since ATM and frame relay were put to rest so
I don’t think that it’s going away any time soon.

I think it would be a serious mistake and sad state of affairs for vendors
to push SR-MPLS and SRv6 and stop development and support of MPLS as that
would really pigeon hole all operators into one technology which does not
fit the bill for every use case out there.

The mention of SR-MPLS pulling support for IPv6 and forcing operators to go
with SRv6 is a wrong move for vendors and would really limit operators with
flexibility to chose based on their use case to stay with traditional mpls
or go with with SR-MPLS or SRv6 only if necessary with their unique use
case warrants.

I think SR-MPLS and SRv6 should be marketed by vendors and the industry as
yet another tool in our operator “design toolbox” to use as we see fit or
not use but not be forced into it.

There are particular use cases for SR-MPLS for migration from existing LDP
and the downside of having state maintained in the core is not a downside
as the P and PE nodes have to be provisioned anyway so their is no savings
in pulling mpls LDP/mLDP with SR-MPLS “Sr-prefer” and ditching LDP.

I think the major use case for SR-MPLS and SRv6 is coloring per-vrf TE
feature for L3 VPNs steering without adding complexity of adding ibgp
loopback egress PE FEC next hop to traffic engineer L3 VPN traffic.  That
is a unique use case and not every major service provider has that
requirement so if you don’t their really is no need to jump on the SR band
wagon and you can stay put with the tried and true mpls that has been
around for decades and is not going away any time soon.

SRv6 has a more ubiquitous all encompassing use case that could serve for
MPLS core replacement or on the public internet or for enterprise network
traffic engineering of flows between data centers or access to data center
and an alternative to SD WAN application based routing solutions.  But here
as well the use case benefit has to exist.  Nobody wants to be forced into
it if it’s unnecessary added complexity.

My 2 1/2 cents

Regards,

Gyan Mishra
Verizon Communications
Cell- 301 502-1347

Sent from my iPhone

On Sep 6, 2019, at 10:17 AM, Robert Raszuk <[e-mail]> wrote:

I don't think so.

In OAM packets are on purpose made huge - even up to MTU to make sure real
customer packets can go through or to detect and diagnose MTU issues. So
adding SRH to it is nothing one can call inefficient.

Wrong tree :)

Cheers,
R.

On Fri, Sep 6, 2019 at 4:14 PM Srihari Sangli <[e-mail]> wrote:

>
>
> On 06/09/19, 4:32 PM Robert Raszuk from [e-mail] said >
>
>
>
> Not really. Only SR OAM packets may need it. Is that a real problem ?
>
>
>
> Thanks for clarification. Like Ron pointed out before, its inefficient
> encoding.
>
>
>
> srihari…
>
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