[c-nsp] STP in L2TPv3

Ge Moua moua0100 at umn.edu
Sat Mar 13 00:55:07 EST 2010


I had a case open with Cisco on this same issue pending for 6 months or 
so then I finally closed the ticket;  what I saw was basically the STP 
pkts was arriving out-of-order due to fragmentation; the remote end 
never get STP updates as such.

I've been meaning to test this with EoMPLS over GRE to see if STP 
behaves the same way; one funny thing I did see though that if I turned 
off the PXF engine on the head-end, then STP gets transmiitted then 
frrag/defrag properly; down side is that PXF engine provides for 
enhanced throughput of L2TPv3 (which is very CPU intensive if process 
switched); in the end Cisco TAC advised us to run VTP domain in 
transparent mode so as not to pass STP pkts; that's what we are doing now.

If I get around to testing STP updates on EoMPLS over GRE then I'll post 
my results on this distro list; good luck.


--
Regards,
Ge Moua
Network Design Engineer

University of Minnesota | OIT - NTS
2218 University Ave SE
Minneapolis, MN 55414-3029
Email: moua0100 at umn.edu | Office: 612.626.2779
--



Chris Flav wrote:
> I am having a devil 
> of a time getting spanning-tree packets to work over a functional L2TPv3 
> tunnel.  I can see arp, cdp, SSDP, and all sorts of other garbage traffic over 
> the link, DHCP works, Internet, the works.
>  
> However, if I 
> connect a catalyst switch on each end and send STP, I do not see the 
> spanning-tree packets on the remote end of the link.
>  
> I am using Cisco 
> 800-series routers (cheating by reversing the Fe4 and Vlan1 ports) and as 
> stated, the L2TPv3 tunnel is reliable and functional, with the exception of 
> STP.  Is there something fundamental I am missing?  See below 
> configs;
>  
>  
> SiteA:
> ======
> l2tp-class 
> l2-dyn
>  authentication
>  hostname MTL
>  password 7 
> 071B29495E08
>  cookie size 8
> !
> !
> pseudowire-class 
> pw-dynamic
>  encapsulation l2tpv3
>  protocol l2tpv3 l2-dyn
>  ip local 
> interface Vlan1
> !
> !
> !
> interface FastEthernet4
>  no ip 
> address
>  duplex auto
>  speed auto
>  no cdp enable
>  xconnect 66.xxx.xxx.xxx 1 
> encapsulation l2tpv3 pw-class pw-dynamic
> !
> interface 
> Vlan1
>  ip address 66.xxx.xxx.xxx 255.255.255.192
>  no ip 
> proxy-arp
>  
>  
> show l2tun session 
> all
>  
> L2TP Session 
> Information Total tunnels 1 sessions 1
>  
> Session id 61551 is 
> up, tunnel id 735
>   Remote session id is 21103, remote tunnel id 25982
>   
> Locally initiated session
> Call serial number is 2414100001
> Remote tunnel 
> name is SHE
>   Internet address is 66.xxx.xxx.21
> Local tunnel name is 
> MTL
>   Internet address is 66.xxx.xxx.195
> IP protocol 115
>   Session is 
> L2TP signaled
>   Session state is established, time since change 00:09:59
>   
> DF bit off, ToS reflect disabled, ToS value 0, TTL value 255
>   UDP checksums 
> are disabled
>   Session cookie information:
>     local cookie, size 8 bytes, 
> value CB 2A 48 48 59 BA 49 A5
>     remote cookie, size 8 bytes, value 0D F2 0A 
> CF 7A ED 2A B4
>   FS cached header information:
>     encap size = 32 
> bytes
>     45000014 00000000 FF73347F 429E81C3
>     42818015 0000526F 
> 0DF20ACF 7AED2AB4
>  
>     1327 Packets 
> sent, 12 received
>     119801 Bytes sent, 1295 received
>   Last clearing of 
> counters never
>   Counters, ignoring last clear:
>     1327 Packets sent, 12 
> received
>     119801 Bytes sent, 1295 received
>     Receive packets 
> dropped:
>       out-of-order:             0
>       total:                    
> 0
>     Send packets dropped:
>       exceeded session MTU:     0
>       
> total:                    0
>   Sequencing is off
>   Conditional debugging is 
> disabled
>   Unique ID is 1
> Session Layer 2 circuit, type is Ethernet, name 
> is FastEthernet4
>   Session vcid is 1
>   Circuit state is UP
>     Local 
> circuit state is UP
>     Remote circuit state is UP
>  
>  
>  
>  
>  
>  
> SiteB:
> =====
>  
> l2tp-class 
> l2-dyn
>  authentication
>  hostname SHE
>  password 7 14031A0E1C0
>  cookie 
> size 8
> !
> !
> pseudowire-class 
> pw-dynamic
>  encapsulation l2tpv3
>  protocol l2tpv3 l2-dyn
>  ip local 
> interface Vlan1
> !
> !
> interface 
> FastEthernet4
>  no ip address
>  duplex auto
>  speed auto
>  no cdp 
> enable
>  xconnect 66.xxx.xxx.195 1 encapsulation l2tpv3 pw-class 
> pw-dynamic
> !
> interface 
> Vlan1
>  ip address 66.xxx.xxx.21 255.255.255.0
>  no ip 
> proxy-arp
>  
> show l2tun session 
> all
>  
> L2TP Session 
> Information Total tunnels 1 sessions 1
>  
> Session id 21103 is 
> up, tunnel id 25982
>   Remote session id is 61551, remote tunnel id 735
>   
> Remotely initiated session
> Call serial number is 15905
> Remote tunnel name 
> is MTL
>   Internet address is 66.xxx.xxx.195
> Local tunnel name is SHE
>   
> Internet address is 66.xxx.xxx.21
> IP protocol 115
>   Session is L2TP 
> signaled
>   Session state is established, time since change 00:12:43
>   DF 
> bit off, ToS reflect disabled, ToS value 0, TTL value 255
>   UDP checksums are 
> disabled
>   Session cookie information:
>     local cookie, size 8 bytes, 
> value 0D F2 0A CF 7A ED 2A B4
>     remote cookie, size 8 bytes, value CB 2A 48 
> 48 59 BA 49 A5
>   FS cached header information:
>     encap size = 32 
> bytes
>     45000014 00000000 FF73347F 42818015
>     429E81C3 0000F06F 
> CB2A4848 59BA49A5
>  
>     14 Packets sent, 
> 1607 received
>     1415 Bytes sent, 145299 received
>   Last clearing of 
> counters never
>   Counters, ignoring last clear:
>     14 Packets sent, 1607 
> received
>     1415 Bytes sent, 145299 received
>     Receive packets 
> dropped:
>       out-of-order:             0
>       total:                    
> 0
>     Send packets dropped:
>       exceeded session MTU:     0
>       
> total:                    0
>   Sequencing is off
>   Conditional debugging is 
> disabled
>   Unique ID is 1
> Session Layer 2 circuit, type is Ethernet, name 
> is FastEthernet4
>   Session vcid is 1
>   Circuit state is UP
>     Local 
> circuit state is UP
>     Remote circuit state is UP
>  
>  
>  
> Any 
> ideas?!
>
>
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