[c-nsp] 6VPE deployment Issue (Core router need configure IPv6 address or not?)

Phil Bedard philxor at gmail.com
Thu Aug 2 12:05:45 EDT 2012

You can tell the ingress PE to not copy (propagate) the TTL value from the
incoming IP packet to the MPLS header, by default it will.  When you turn
on the feature to not propagate TTL, it will use a value of 255 for the
MPLS header, so this will tunnel any IP packets across the MPLS network
making it look like a single IP hop.  If you don't do this,  you'll need
to configure IPv6 on the P routers so they can send the proper response
back to the original host.  Personal preference but it's easier to just
turn off TTL propagation.

As for QoS you shouldn't lose the original QoS markings unless you
configure it do so.


On 8/1/12 4:45 PM, "Aaron" <aaron1 at gvtc.com> wrote:

>My understanding is...
>P router isn't seen in vpvn4, unless on trace route because of ttl
>propagate....you can disable it and make the mpls core invisible
>I recall someone (Pshem) telling me that for 6vpe the address family for
>vpnv6 needs to be enabled on pe's (6vpe neighbors you choose to do 6vpe
>with) (and route reflector if you choose to have one)
>Traces and pings from ce to ce I don't believe by design of mpls l3vpn's
>or 6) are supposed to see core.
>Don't know much about qos, but be aware of single label situation where
>causes exp bits to be lost prior to pe arrival... your case(s) of l3vpn's
>vpnv4/6 shouldn't apply since the have stacked labels.
>Hu please check me on all this as I'm fairly new to this myself.  I'm at
>beginnings of my 6vpe deployment too.  This community is so knowledgeable
>that I will look for others to confirm or deny my understandings and then
>grow from it.
>-----Original Message-----
>From: cisco-nsp-bounces at puck.nether.net
>[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Xu Hu
>Sent: Wednesday, August 01, 2012 10:30 AM
>To: cisco-nsp at puck.nether.net
>Subject: [c-nsp] 6VPE deployment Issue (Core router need configure IPv6
>address or not?)
>Hi All Experts,
>Let's say the topology as below:
>PE-CE protocol OSPF, core running OSPF as IGP, on top have MPLS/VPN, LDP.
>In the IPv4 situation, when i ping from CE-1 to CE-2, will see the
>of P router.
>For the IPv6 situation, PE-1 and PE-2 running 6VPE, established the VPNv6
>neighbor with each other, as we know the core router is unaware of IPv6,
>by right we just need to configure the IPv6 address in PE interface which
>towards CE side.
>My question is if we don't configure the IPv6 address in the core, so how
>the traceroute and ping work?
>Also another thing is the QOS deployment, if we don't configure the IPv6
>address, the DSCP value in the core will change or not by default? Or we
>must map the DSCP value to EXP value in the ingress router?
>Thanks advance for any comments,
>Hu Xu
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