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Selective VRF download (SVD) is on by default starting 4.2.0

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xthuijs
Cisco Employee

folks, we see an increasing number of TAC cases relating to forwarding issues in MPLS/VPN scenarios (including 6vPE).

Starting in XR release 4.2.0 we have a functionality that is called Selective VRF download which will only install routes for vrf's on those linecards

that are interested in it. It seggregates between customer/edge and core facing LC's. The benefit is that if you have lower FIB scale cards on your edge with one LC supporting vrf X and another LC supporting vrf Y, then the LC supporting X would not get the FIB/LFIB tables for vrf Y.

Core facing LC's will have both.

Now it doesn't only pertain to FIB entries but also LPTS entries and if you are getting say a packet in mpls encapped for a vrf a particular receiving LC may not have the proper LPTS directives for it. One workaround is to create a dummy subinterface and put it in the vrf that you are expecting this for to pierce that hole.

In general however we recommend to DISABLE svd for asr9000, which unfortunately requires a reload on teh LC's to activate that change.

You can track the SVD state via show svd [state|role]

We're working to make this off by default starting a release (not defined yet) but in the interim the story above applies.

11 Comments

Hello Alex,

I am reading you Cisco Live presentation for the ASR9000 (Orlando 2013) and I would like to know the maximum routes supported within a vrf on a ASR9010 with RSP440-TR.

Thanks,

xthuijs
Cisco Employee

Hi JeanMarie,

the number of routes is not so much dependent on the RSP, but more so the LC in use:

https://supportforums.cisco.com/docs/DOC-25489

Trident either 512k, 1M or 1.3M depending on the scale profile used. Typhoon cards have 4M.

RIB can be much larger, but not all routes can be installed into the FIB (due to LC limitations). RIB size is dependent on path attributes and mem consumption. 17M is possible.

xander

The VPNs are configured on a TYPHOON line card (A9K-MOD-160) with one MPA-2x40GE. I would like to know the L3VPN scale for this particular card. I am also reviewing the design of another huge company where they're juniper platforms (MX960, MX2020) on the core backbone.

xthuijs
Cisco Employee

that is a typhoon card and you have 4M routes total, doesn't matter where they are (vrf wise).

for instance 1M global, 2M vrf-X and 1M in vrf-Y or 3M global, 500k vrf-X, 200k vrf-Y, 300k vrf-Z

xander

Perfect!!! That's exactly what I am looking for.

Thank you Sir...

atif_hafeez
Beginner

Hi Alex,

Please advise how to disable this feature?

Best regards!

xthuijs
Cisco Employee

hi atif, that could not be more simple (for once )

selective-vrf-download disable

you need to reload the LC's to have this taken effect.

you can verify the svd state with "show svd state"

regards

xander

atif_hafeez
Beginner

Hi Alex,

Thank you for your quick response. I tried this command but the system did'nt recognise it. Here output from the node i am using:

ASR9K#show svd state

Selective VRF Download (SVD) Feature State:

SVD Configuration State        Unsupported

SVD Operational State          Unsupported

ASR9K#show svd role

Codes: (C) : user Configured role
Node Name       IPv4 Role                 IPv6 Role
--------------------------------------------------------------------
0/RSP1/CPU0     Standard                  Standard
0/0/CPU0        Standard                  Standard
0/1/CPU0        Standard                  Standard
0/2/CPU0        Standard                  Standard
0/4/CPU0        Standard                  Standard
0/6/CPU0        Standard                  Standard
0/7/CPU0        Standard                  Standard

ASR9K#show install summary

Default Profile:

  SDRs:

    Owner

  Active Packages:

    disk0:asr9k-mpls-px-4.3.4

    disk0:asr9k-9000v-nV-px-4.3.4

    disk0:asr9k-doc-px-4.3.4

    disk0:asr9k-fpd-px-4.3.4

    disk0:asr9k-k9sec-px-4.3.4

    disk0:asr9k-mcast-px-4.3.4

    disk0:asr9k-mgbl-px-4.3.4

    disk0:asr9k-mini-px-4.3.4

    disk0:asr9k-services-px-4.3.4

Please advise!

xthuijs
Cisco Employee

Then you're all set. At the time I wrote this blog post there was no definitive release when we would turn it off by default.

But starting 4.3.1 as per CSCue04721 we finally turned it off by default for the a9k.

So in your 434 release as you had noticed, it is no longer operational by default.

regards

xander

hoses
Cisco Employee

Just to update current default settings:

1. Releases before 4.3.1

    - Selective VRF download enabled by default

    - To disable it:

selective-vrf-download disable

2. Releases after 4.3.1

    - Selective VRF download disabled by default

    - To enable it:

svd platform enable

You can search for the commands and defaults in the documentation. For example this one for 5.3.1:

http://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k_r5-3/routing/command/reference/b-routing-cr53xasr9k/b-routing-cr53xasr9k_chapter_01.html

hoses
Cisco Employee

Hi Alex,

Something interesting we just found while testing the configuration differences between a CRS running 5.1.3 and a future ASR9922 that will run 5.3.2 (5.3.3 in future) with the same features, is that the command "svd platform enable" is not present in the ASR9922.

Moreover it appears in the following command as UnSupported:

RP/0/RP0/CPU0:9K22-4212#show svd state

Fri Feb 19 12:17:38.859 UTC

Selective VRF Download (SVD) Feature State:

SVD Configuration State        Unsupported

SVD Operational State          Unsupported.

Has this feature been discontinued? Can you point me to the document about it?

Best regards

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