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SRST: Phones not registering using VRF and MPLS



I have a point - to - multi point MPLS network that is using VRF groups with MPLS/EIGRP/BGB (I am not verify familiar with routing protocols).  When a phone goes into srst mode, they do not register with the local gateway.  I am able to replicate this in a lab environment.

Topology is thus:

IP Phone connected to 3750 access switch

3750 Access switch connected to 2921 ISR (datak9 (eval), uck9 (eval))  IOS is: c2900-universalk9-mz.SPA.152-4.M1.bin.

2921 connected to production 6500

6500 connected to production 2921 (WAN gateway)

Lab CUCM connected to access switch connected to 6500

ip vrf voice

rd 30:30

route-target export 30:30

route-target import 30:30


multilink bundle-name authenticated


mpls label protocol ldp

voice vrf voice


voice service voip


interface Loopback0

ip address


interface GigabitEthernet0/0

description WAN link to MPLS

ip address

duplex full

speed 100

mpls mtu 1508

mpls ip

no cdp enable


interface GigabitEthernet0/1

description link to site switch

no ip address

duplex auto

speed auto


interface GigabitEthernet0/1.2000

description Local Voice Network

encapsulation dot1Q 2084

ip vrf forwarding voice

ip address

ip helper-address

ip helper-address

mpls ip


router eigrp 100




redistribute static


router bgp 100

bgp log-neighbor-changes

neighbor remote-as 100

neighbor update-source Loopback0



group 1 vrf voice

  ip source-address port 2000


srst mode auto-provision none

srst dn line-mode dual

max-ephones 12

max-dn 24

max-conferences 8 gain -6

transfer-system full-consult


When null0 routing to the CallManager (ip route vrf voice null0), the device loses connectivity and begins searching.  The device never registers with the gateway, but I do get this from a 'debug ip tcp trans'

Reserved port 0 in Transport Port Agent for TCP IP type 0

TCP: connection attempt to port 2000

TCP: sending RST, seq 0, ack 2207086699

TCP: sent RST to from

Released port 0 in Transport Port Agent for TCP IP type 0 delay 240000

TCP0: state was LISTEN -> CLOSED [0 -> UNKNOWN(0)]

TCB 0x31D49BD4 destroyed

TCP0: ACK timeout timer expired

TCP0: ACK timeout timer expired

TCP0: ACK timeout timer expired

I am able to ping the device from the vrf ('ping vrf voice') and from extended pings from interface g0/0 (traceroute actually sends this traffic back to the WAN router and from their back to the lab (remote) router), but not from the subinterface g0/1.2000.  From what I am attempting to understand from vrf docs is that this is normal.  I do have an SR on-going with TAC on this, but I thought I'd ping the community to see if there is any others who have seen this.



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