3750me - eompls and stp

barbara.costantini · ‎01-05-2005

In the lab I have six routers connected as described below

[CE-3550-12T]-[PE1-3750me]--[P1-6500sup720]--[P2-3750me]--[PE2-3750me]-[CE-3550-12G]

I've enabled mpls on the PE e P routers and I've configurated an Eompls tunnel between two PE routers.(vc id 300)

I've connected on the fast 1/0/5 in both PEs two catalyst 3550 as CE routers.

I'd like to carry transparently the CE's vlans (16,17) on the backbone mpls so I've configurated the fast 1/0/5 in both PE in mode dot1q tunnel and in access vlan 300.

interface FastEthernet1/0/5

description EOMPLS PE1

switchport access vlan 300

switchport mode dot1q-tunnel

switchport protected

load-interval 30

mdix auto

l2protocol-tunnel shutdown-threshold cdp 600

l2protocol-tunnel shutdown-threshold stp 600

l2protocol-tunnel shutdown-threshold vtp 600

l2protocol-tunnel drop-threshold cdp 400

l2protocol-tunnel drop-threshold stp 400

l2protocol-tunnel drop-threshold vtp 400

l2protocol-tunnel cdp

l2protocol-tunnel stp

l2protocol-tunnel vtp

no cdp enable

spanning-tree bpdufilter enable

end

interface Vlan300

no ip address

mpls l2transport route 172.9.9.9 300 vc-type vlan

tag-switching ip

end

The spanning-tree of vlan 300 is disabled whereas stp is enabled for the ce's vlans (16 17).

The eompls tunnel goes up and I've IP connectivity between CE routers.

PE2#sh mpls l2transport vc 300 detail

vcid: 300, type: vlan , local groupid: 63, remote groupid: 58 (vc is up)

client: Vl300 is up, destination: 172.9.9.9, Peer LDP Ident: 172.9.9.9:0

local label: 24, remote label: 96, tunnel label: 22

outgoing interface: Vl3002, next hop: 172.19.9.17

Local MTU: 1504, Remote MTU: 1504

Remote interface description: Vlan300

Packet totals(in/out): 1312/1313

byte totals(in/out): 143440/148796

But I note that both CE routers are root bridge for vlan 16,17 and on both PE routers the counters of stp encapsulated packets increase whereas the counters of stp de-capsulated packets are zero.

PE2#SH L2protocol-tunnel INterface FAST 1/0/5

COS for Encapsulated Packets: 5

Port Protocol Shutdown Drop Encapsulation Decapsulation Drop

Threshold Threshold Counter Counter Counter

-------- -------- --------- --------- ------------- ------------- -------------

Fa1/0/5 cdp 600 400 0 0 0

stp 600 400 3 0 0

vtp 600 400 0 0 0

---- ---- ---- ---- ---- ----

Is my configuration incorrect?

Why doesn't the eompls tunnel carry across the backbone the stp packets?

Must I set the "vlan dot1q tag native" on the PE and CE routers?

Thanks in advance

B.

romccallum · ‎01-10-2005

two things - try disabling spanning tree for vlan 300 on the 3750. Also try to change the vc-type to ethernet instead of vlan.

barbara.costantini · ‎01-14-2005

Thanks for the help

I've tried but the result is the same.

I think that the problem is this bug

CSCee30284

The EoMPLS tunneled ports (both port-based and VLAN-based) on a switch do not tunnel Layer 2 protocol packets that are received from the customer switch to the remote (egress) provider edge switch. The Layer 2 protocols packets are either consumed by the switch or, if Layer 2 protocol tunneling is enabled, are passed along by the standard Layer 2 protocol tunneling mechanism (outside the EoMPLS tunnels).

There is no workaround.

Thanks for all

B.

martyf · ‎01-20-2005

You are correct. I have run into the same issue. Suggested solution was to place 3550s in front of the 3750 to do your l2tunnel.

In my case, it was CDP. This option may or may not work for you.

alex.torres · ‎03-15-2005

Hi,

as far as I know there's no stp forwarding in eompls circuits.

I have no idea if they have added this functionality in any other IOS version.

romccallum · ‎03-15-2005

lookup l2protocol tunnel mate - you can do vtp, stp and cdp.

kayjoon · ‎01-20-2005

ok

istein001 · ‎04-21-2012

I know this is old... but :

spanning-tree bpdufilter enable -> filters all STP BPDU's... so they don't even get encasulated and passed on.

We use this when customers have configured their STP or Trunk ports incorreclty and are gettting error disabled ports, when we know they have a loop free topology.