Date created: Wednesday, September 9, 2015 11:20:51 AM. Last modified: Friday, August 10, 2018 3:44:36 PM
MST over L2TPv3
Recap on MST
References:
http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_52_se/configuration/guide/3560scg/swmstp.html
http://packetlife.net/blog/2010/apr/26/multiple-spanning-tree-mst/
This example topology shows two end sites with dual provider CPEs and dual customer switches. CPE 1 and 3 have a layer 2 port-based xconnect between them (using L2TPv3) that transports VLAN headers and BPDUs and L2CPs (this is becasue it's port based and these are 1941's with xconnect on the built in layer 3 interfaces). CPE 2 and 4 also have the same tunnel, which completes a layer 2 loop so MST is running to close the link between SW4 and CPE4.
Side Note: HSRP was tested running on VLANs 10 and 20 over the stretched layer 2 infrastructure which worked fine.
2nd Side Note: UDLD is being passed (as would be expected using port based xconnect) using the interface config "udld port aggressive" on the switch ports between SW1 and SW3 and between SW2 and SW4.
This is a basic MST configuration, instance 0 is for layer 2 VLANs (10, 20) stretched over the WAN, instance 1 is for VLANs terminated locally (100, 200) and routed across the WAN.
! This is applied to all four switches: spanning-tree mst configuration name Region1 revision 1 instance 1 vlan 100, 200 ! ! By moving VLANs 100 and 200 into instance 1, that leaves VLANs 10 and 20 in instance 0 by default ! spanning-tree mst hello-time 1 spanning-tree mst forward-time 4 spanning-tree mst max-age 6 ! vlan 10 name L2-VLAN-10 ! vlan 20 name L2-VLAN-20 ! vlan 100 name L3-VLAN-100 ! vlan 200 name L3-VLAN-200 interface GigabitEthernet0/1 description L2 Trunk to 1941 Gi0/0 switchport trunk encapsulation dot1q switchport trunk allowed vlan 10,20 switchport mode trunk ! interface GigabitEthernet0/2 description L2 Trunk to OtherSwitch Fa1/0/2 switchport trunk encapsulation dot1q switchport trunk allowed vlan 10,20,100,200 switchport mode trunk ! interface GigabitEthernet0/3 description L3 Trunk to 1941 Fa0/0/3 switchport trunk encapsulation dot1q switchport trunk allowed vlan 100,200 switchport mode trunk interface Vlan10 ip address 192.168.10.2 255.255.255.0 ! interface Vlan20 ip address 192.168.20.2 255.255.255.0 !
Check that SW1 (the ME3750) is the root bridge in MST instance 0 for all switches (verifying that BPDUs are being passed over the L2TPv3 pseudowires):
! Note, the pseudowire from CPE1 to CPE3 is down at the time these captures are taken so the root ports at site 2 point towards the pseudowire between CPE2 and CPE4
SW1#show spanning-tree mst 0
##### MST0 vlans mapped: 1-99,101-199,201-4094
Bridge address 0025.46fd.ea00 priority 4096 (4096 sysid 0)
Root this switch for the CIST
Operational hello time 1 , forward delay 4 , max age 6 , txholdcount 6
Configured hello time 1 , forward delay 4 , max age 6 , max hops 20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa1/0/1 Desg FWD 200000 128.3 P2p
Fa1/0/2 Desg FWD 200000 128.4 P2p
Fa1/0/3 Desg FWD 200000 128.5 P2p Bound(PVST)
SW2#show spanning-tree mst 0
##### MST0 vlans mapped: 1-99,101-199,201-4094
Bridge address 3c08.f67d.3600 priority 32768 (32768 sysid 0)
Root address 0025.46fd.ea00 priority 4096 (4096 sysid 0)
port Gi0/2 path cost 0
Regional Root address 0025.46fd.ea00 priority 4096 (4096 sysid 0)
internal cost 200000 rem hops 19
Operational hello time 1 , forward delay 4 , max age 6 , txholdcount 6
Configured hello time 1 , forward delay 4 , max age 6 , max hops 20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi0/1 Desg FWD 20000 128.1 P2p
Gi0/2 Root FWD 200000 128.2 P2p
Gi0/3 Desg FWD 200000 128.3 P2p Bound(PVST)
SW3#show spanning-tree mst 0
##### MST0 vlans mapped: 1-99,101-199,201-4094
Bridge address 381c.1a5e.8e00 priority 32768 (32768 sysid 0)
Root address 0025.46fd.ea00 priority 4096 (4096 sysid 0)
port Gi1/0/2 path cost 0
Regional Root address 0025.46fd.ea00 priority 4096 (4096 sysid 0)
internal cost 240000 rem hops 17
Operational hello time 1 , forward delay 4 , max age 6 , txholdcount 6
Configured hello time 1 , forward delay 4 , max age 6 , max hops 20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi1/0/1 Desg FWD 20000 128.1 P2p
Gi1/0/2 Root FWD 20000 128.2 P2p
Gi1/0/3 Desg FWD 200000 128.3 P2p Bound(STP)
SW4#show spanning-tree mst 0
##### MST0 vlans mapped: 1-99,101-199,201-4094
Bridge address c47d.4fc1.bf08 priority 32768 (32768 sysid 0)
Root address 0025.46fd.ea00 priority 4096 (4096 sysid 0)
port Gi1/1 path cost 0
Regional Root address 0025.46fd.ea00 priority 4096 (4096 sysid 0)
internal cost 220000 rem hops 18
Operational hello time 1 , forward delay 4 , max age 6 , txholdcount 6
Configured hello time 1 , forward delay 4 , max age 6 , max hops 20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi1/1 Root FWD 20000 128.1 P2p
Gi1/2 Desg FWD 20000 128.2 P2p
Gi1/3 Desg FWD 20000 128.3 P2p
Change SW4 to be the root bridge in MST instance 0 (again verifying that the BPDUs are traversing the L2TPv3 pseudowires):
! Note, the pseudowire from CPE1 to CPE3 is down at the time these captures are taken
SW4(config)#spanning-tree mst 0 priority 0
SW1#show spanning-tree mst 0
##### MST0 vlans mapped: 1-99,101-199,201-4094
Bridge address 0025.46fd.ea00 priority 4096 (4096 sysid 0)
Root address c47d.4fc1.bf08 priority 0 (0 sysid 0)
port Fa1/0/2 path cost 0
Regional Root address c47d.4fc1.bf08 priority 0 (0 sysid 0)
internal cost 220000 rem hops 18
Operational hello time 1 , forward delay 4 , max age 6 , txholdcount 6
Configured hello time 1 , forward delay 4 , max age 6 , max hops 20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa1/0/1 Desg FWD 200000 128.3 P2p
Fa1/0/2 Root FWD 200000 128.4 P2p
Fa1/0/3 Desg FWD 200000 128.5 P2p Bound(PVST)
SW2#show spanning-tree mst 0
##### MST0 vlans mapped: 1-99,101-199,201-4094
Bridge address 3c08.f67d.3600 priority 32768 (32768 sysid 0)
Root address c47d.4fc1.bf08 priority 0 (0 sysid 0)
port Gi0/1 path cost 0
Regional Root address c47d.4fc1.bf08 priority 0 (0 sysid 0)
internal cost 20000 rem hops 19
Operational hello time 1 , forward delay 4 , max age 6 , txholdcount 6
Configured hello time 1 , forward delay 4 , max age 6 , max hops 20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi0/1 Root FWD 20000 128.1 P2p
Gi0/2 Desg FWD 200000 128.2 P2p
Gi0/3 Desg FWD 200000 128.3 P2p Bound(PVST)
SW3#show spanning-tree mst 0
##### MST0 vlans mapped: 1-99,101-199,201-4094
Bridge address 381c.1a5e.8e00 priority 32768 (32768 sysid 0)
Root address c47d.4fc1.bf08 priority 0 (0 sysid 0)
port Gi1/0/2 path cost 0
Regional Root address c47d.4fc1.bf08 priority 0 (0 sysid 0)
internal cost 20000 rem hops 19
Operational hello time 1 , forward delay 4 , max age 6 , txholdcount 6
Configured hello time 1 , forward delay 4 , max age 6 , max hops 20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi1/0/1 Desg FWD 20000 128.1 P2p
Gi1/0/2 Root FWD 20000 128.2 P2p
Gi1/0/3 Desg FWD 200000 128.3 P2p Bound(STP)
SW4#show spanning-tree mst 0
##### MST0 vlans mapped: 1-99,101-199,201-4094
Bridge address c47d.4fc1.bf08 priority 0 (0 sysid 0)
Root this switch for the CIST
Operational hello time 1 , forward delay 4 , max age 6 , txholdcount 6
Configured hello time 1 , forward delay 4 , max age 6 , max hops 20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi1/1 Desg FWD 20000 128.1 P2p
Gi1/2 Desg FWD 20000 128.2 P2p
Gi1/3 Desg FWD 20000 128.3 P2p
Here the output of "show cdp neigbours" on SW4 (ME6524) shows SW3 (2960S) and SW2 (3560E) verifying that other L2CP frames are transported over the L2TPv3 pseudowires in addition to BPDUs:
ME6524#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
D - Remote, C - CVTA, M - Two-port Mac Relay
Device ID Local Intrfce Holdtme Capability Platform Port ID
3560E Gig 1/1 156 R S I WS-C3560X Gig 0/1
2960S Gig 1/2 127 S I WS-C2960S Gig 1/0/2
Port based xconnects on 1941s/2921s/2951s (ISR G2s in general) using L2TPv3 will transport VLAN tags and BPDUs/L2CPs as shown. The MTU for the local switch facing interface Gi0/0 on each CPE router is not changed from the standard 1500. In classical IOS extra layer 2 headers like VLAN tags aren't counted when a frame comes in/out.
On the WAN facing interfaces, the Gi0/1's on each CPE where the pseudowires are routing across the WAN, the MTU is set to 1542. That accounts for 70 bytes of headers including the customer's layer 2 headers but excluding the layer 2 headers of the WAN CPEs themselves, as follows:
Total bytes on the wire between CPEs when pinging from SW2 (192.168.20.2) to SW4 (192.168.20.4) is 1560 bytes:
14 bytes Ethernet header between CPE WAN interfaces
+ 4 byte VLAN tag and ethertype between CPE WAN interfaces (VLAN 300 in this example which is hex 012C, CoS 0)
+ 20 bytes IP header between WAN CPEs (192.168.30.2 to 192.168.30.4 in this example)
+ 4 bytes L2TP header between WAN CPEs
+ 14 bytes Ethernet headers between end site switches (SW2 and SW4)
+ 4 bytes VLAN and ethertype between end site switches (VLAN 20 in this example, hex 14, Cos 0)
+ 20 bytes IP header between end site switches (192.168.20.2 to 192.168.20.4)
+ 8 bytes ICMP header between end site switches
+ 1472 bytes ICMP payload between end site switches (they are configured with MTU 1500, so they -20 bytes IP header and 8 bytes ICMP header)
Adding all those headers captured "on the wire" between CPEs gives 88 bytes of headers total, but the first 18 bytes are the layer 2 headers of the WAN CPEs themselves. As per above classical IOS doesn't count this in the interface MTU configuration so of the 1560 bytes on the wire, 1560-18 = 1542, is the required MTU size for the WAN facing interface Gi0/1 on each CPE.
Another way of calculating this; For this example customer wanting to send 1500 bytes of layer 2 payload, the CPEs must also include an extra 18b ytes for the customer's layer 2 headers and 20 bytes of IP and 4 bytes of L2TP headers for WAN transport, making a total of 1542 bytes.
This is the output of a packet capture on CPE4 when pinging from SW2 (MAC 3c08.f67d.3643, 192.168.20.2 in hex C0A81402) to SW4 (MAC c47d.4fc1.bf08, 192.168.20.4 in hex C0A81404) which is passed over the pseudowire between CPE2 (MAC 442b.0375.46a1, 192.168.30.2 in hex C0A81E02) and CPE4 (MAC a80c.0de2.4011, 192.168.30.4 in hex C0A81E04) as the pseudowire between CPE1 and CPE3 was down at the time of capture):
2951-4#monitor capture buffer cb size 1024 max-size 2000 2951-4#monitor capture point ip cef cpc gi0/1 both 2951-4#monitor capture point associate cpc cb 2951-4#monitor capture point start cpc SW2#show ip arp vlan 20 Protocol Address Age (min) Hardware Addr Type Interface Internet 192.168.20.4 0 c47d.4fc1.bf08 ARPA Vlan20 Internet 192.168.20.1 0 0025.46fd.ea41 ARPA Vlan20 Internet 192.168.20.2 - 3c08.f67d.3643 ARPA Vlan20 Internet 192.168.20.3 71 381c.1a5e.8e42 ARPA Vlan20 SW2#ping 192.168.20.4 repeat 1 df-bit size 1500 Type escape sequence to abort. Sending 1, 1500-byte ICMP Echos to 192.168.20.4, timeout is 2 seconds: Packet sent with the DF bit set ! Success rate is 100 percent (1/1), round-trip min/avg/max = 8/8/8 ms 1941-2#show ip arp GigabitEthernet 0/1.300 Protocol Address Age (min) Hardware Addr Type Interface Internet 192.168.30.2 - 442b.0375.46a1 ARPA GigabitEthernet0/1.300 Internet 192.168.30.4 192 a80c.0de2.4011 ARPA GigabitEthernet0/1.300 2951-4#monitor capture point stop cpc 2951-4#show monitor capture buffer cb dump 15:57:01.953 UTC Sep 10 2015 : IPv4 LES CEF : Gi0/1.300 None 022ECA70: A80C0DE2 4011442B (..b@.D+ 022ECA80: 037546A1 8100012C 08004500 0606E322 .uF!...,..E...c" 022ECA90: 0000FE73 160BC0A8 1E02C0A8 1E04BF40 ..~s..@(..@(..?@ 022ECAA0: 48CEC47D 4FC1BF08 3C08F67D 36438100 HN8..^.B<.v}6C.. 022ECAB0: 00140800 450005DC 0FC94000 FF01BD01 ....E..\.I@...=. 022ECAC0: C0A81402 C0A81404 0800801E 00150000 @(..@(.......... 022ECAD0: 00000000 00223793 ABCDABCD ABCDABCD ....."7.+M+M+M+M 022ECAE0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECAF0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECB00: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECB10: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECB20: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECB30: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECB40: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECB50: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECB60: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECB70: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECB80: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECB90: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECBA0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECBB0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECBC0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECBD0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECBE0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECBF0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECC00: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECC10: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECC20: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECC30: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECC40: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECC50: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECC60: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECC70: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECC80: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECC90: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECCA0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECCB0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECCC0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECCD0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECCE0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECCF0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECD00: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECD10: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECD20: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECD30: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECD40: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECD50: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECD60: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECD70: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECD80: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECD90: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECDA0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECDB0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECDC0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECDD0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECDE0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECDF0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECE00: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECE10: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECE20: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECE30: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECE40: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECE50: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECE60: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECE70: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECE80: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECE90: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECEA0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECEB0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECEC0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECED0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECEE0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECEF0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECF00: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECF10: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECF20: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECF30: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECF40: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECF50: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECF60: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECF70: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECF80: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECF90: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECFA0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECFB0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECFC0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECFD0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECFE0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ECFF0: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ED000: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ED010: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ED020: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ED030: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ED040: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ED050: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ED060: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ED070: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ED080: ABCDABCD ABCDABCD ABCDABCD ABCDABCD +M+M+M+M+M+M+M+M 022ED090: 00 . ! This last null byte on the end is a dummy/padding byte 14 bytes Ethernet header between WAN CPE interfaces A80C0DE24011 442B037546A1 8100 4 byte VLAN tag and ethertype between WAN CPE interfaces 012C 0800 20 bytes IP header between WAN CPEs 45000606 E3220000 FE73160B C0A81E02 C0A81E04 4 bytes L2TP header between WAN CPEs BF4048CE 14 bytes Ethernet headers between end site switches C47D4FC1BF08 3C08F67D3643 8100 4 bytes VLAN and ethertype between end site switches 0014 0800 20 bytes IP header between end site switches 450005DC 0FC94000 FF01BD01 C0A81402 C0A81404 8 bytes ICMP header between end site switches 0800801E 00150000 The rest is payload.
This is the config on the ISR-G2 CPEs (1941-2 in this case):
no spanning-tree vlan 100 no spanning-tree vlan 200 vlan 100 name L3-VLAN-100 vlan 200 name L3-VLAN-200 pseudowire-class L2TPv3 encapsulation l2tpv3 ip local interface GigabitEthernet0/1.300 interface GigabitEthernet0/0 description xconnect to SW2 (3560E) Gi0/1 no ip address duplex auto speed auto xconnect 192.168.30.4 456 encapsulation l2tpv3 pw-class L2TPv3 interface GigabitEthernet0/1 description Link to WAN mtu 1542 no ip address interface GigabitEthernet0/1.300 description /24 between WAN CPEs encapsulation dot1Q 300 ip address 192.168.30.2 255.255.255.0 interface FastEthernet0/0/3 description L3 Trunk to SW2 (3560E) Gi0/3 switchport trunk allowed vlan 1,100,200,1002-1005 switchport mode trunk no ip address interface Vlan100 description Routed Subnet 100 ip address 192.168.101.252 255.255.255.0 no ip redirects no ip unreachables no ip proxy-arp
standby 100 ip 192.168.101.254 standby 100 priority 254 standby 100 preempt interface Vlan200 description Routed Subnet 200 ip address 192.168.201.252 255.255.255.0 no ip redirects no ip unreachables no ip proxy-arp
standby 200 ip 192.168.201.254 standby 200 priority 254 standby 200 preempt 1941-2#show xconnect all detail Legend: XC ST=Xconnect State S1=Segment1 State S2=Segment2 State UP=Up DN=Down AD=Admin Down IA=Inactive SB=Standby HS=Hot Standby RV=Recovering NH=No Hardware XC ST Segment 1 S1 Segment 2 S2 ------+---------------------------------+--+---------------------------------+-- UP pri ac Gi0/0:3(Ethernet) UP l2tp 192.168.30.4:456 UP Interworking: none Session ID: 960363062 Tunnel ID: 3540866178 Protocol State: UP Remote Circuit State: UP pw-class: L2TPv3
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