[c-nsp] GRE fragmentation and ASR9001

[Adam Vitkovsky]

Hi Gert,

There are counters suggesting that IPv4 frames are punted to LC CPU to be fragmented.

sh controllers np descriptions location 0/x/cpu0

RSV_PUNT_IP_MTU_EXCEEDED                                  L3       Egress IP packets that exceed the interface MTU.  IPv4 frames are punted to LC CPU to be fragmented. IPv6 frames are punted to LC CPU be dropped and generate ICMP response.Punt rate limit is very low to protect LC CPU

IPV4_FRAG_NEEDED_PUNT                                     Punt     IP MTU Exceeded. Punted to CPU for fragmentation

MPLS_FRAG_NEEDED_PUNT                                     Punt     MPLS packet for which fragmentation is required

IPV4_FRAG_TUNNEL                                          Punt     Not implemented by ucode
-this one actually concerns me
-does it mean it's going to be slow, or punted to RP, or just dropped
-not sure what I should make up from this



adam
>

        Adam Vitkovsky
        IP Engineer

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-----Original Message-----
> From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of
> Gert Doering
> Sent: 11 August 2015 09:53
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] GRE fragmentation and ASR9001
>
> Hi,
>
> my google fu is failing me - so apologies if this is in easily findable
> documentation...
>
> I want (need) to connect two ASR9001s over a GRE tunnel "across the
> public Internet" (= outside MTU 1500), but need to provide a larger inner
> MTU (~1600).  So, fragmentation and reassembly required.
>
> Easy question: can the ASR9001 do that (in hardware, obviously)?
>
> Pointers to documentation appreciated :-)
>
> (Current XR release is 4.3.4, but knowing that "it is supported starting
> in 5.17.4" would also be useful information)
>
> gert
> --
> USENET is *not* the non-clickable part of WWW!
>                                                            //www.muc.de/~gert/
> Gert Doering - Munich, Germany                             gert at greenie.muc.de
> fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de