Gre tunnel unable to Ping when cisco 7600 as a PE

Problem:- If you are using cisco 7600 as a PE router and configuring Vrf forwarding over GRE then you will be unable to ping CE side GRE tunnel ip from Remote PE.

Solution:-put a global command on Cisco 7600 PE "mls mpls tunnel-recir".

Cause:-Packet gets corrupted when it is received from CE back to PE, so conversion of IPv4 to MPLS doesn't happen.

IP precedence value over L2tpv3

To reflect ip precedence value over l2tpv3, you can use Ip tos reflect command under psuedowire configuration.

PE to CE eigrp flapping in mpls/vpn scenario

In this post i am explaining one case of Eigrp neighborship is flapping between PE to CE over L2tpv3 in MPLS VPN scenario, it could be the bug if you are using entservicesk9-mz.123-14.T5.bin IOS.

please find the attached scenario.

IP Dialing

Scenario :- in this scenario we are using LNS only (layer2 network server ) for both function authentication and IP assigning).
Here we are considering you have ip reachability of that IP which you are dialing please find below mention diagram for the same.














Required Configuartion for LNS
interface Loopback226
ip address 20.235.21.1 255.255.255.248 (according to this 6 IPs are valid)
(This loopback is created to map a interface with virtual-templete and pool has been created to specify the range of ip assigning. The subnet mask of loopback interface according to the pool)
vpdn enable
vpdn-group 1 (Creates VPDN group for the LNS)
! Default PPTP VPDN group (this command will come automatic)
accept-dialin (Creates an accept dial-in VPDN subgroup.)

protocol pptp--- (Specifies PPTP as the tunneling protocol).

virtual-template 5---- (Instructs the LNS to clone virtual access interfaces for VPDN sessions from virtual template 5).


interface Virtual-Template5 ( Creates virtual template 5, which is used to clone virtual access interfaces for incoming
VPDN sessions).

ip unnumbered Loopback226 (Specifies that the virtual access interfaces will use the IP address of loopback226)


peer default ip address pool TEST1 (Instructs the LNS to assign an IP address to VPDN sessions from the Test1
pool).
ppp authentication pap chap (Specifying ppp autentication method)
ip local pool TEST1 20.235.21.1 20.235.21.6
username cisco privilege 15 password 0 xxxx (Specifying the username & password for PC)