10-07-2013 01:25 PM - edited 03-04-2019 09:15 PM
Hello,
I have a problem with MTU in a xconnect using L2Tv3. I do not change the MTU in the host.
I can check that ip tcp mss adjust command in the xconnect interface does not work.
The performace now is very bad. If I change the MTU in the host then performance is better.
So I think is a MTU issue. Any ideas?.
Thanks.
This is my configuration:
FINTEGRA-SEDE-RT01#sh run
Building configuration...
hostname FINTEGRA-SEDE-RT01
!
ip cef
!
l2tp-class class1
authentication
hello 12
password 7 XXXX
retransmit retries 5
!
!
multilink bundle-name authenticated
vpdn enable
!
vpdn-group pppoe
!
!
pseudowire-class PSVLANS
encapsulation l2tpv3
protocol l2tpv3 class1
ip local interface Dialer0
!
!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
media-type rj45
no negotiation auto
!
!
interface GigabitEthernet0/1.1
encapsulation dot1Q 1
xconnect X.X.X.186 1 encapsulation l2tpv3 pw-class PSVLANS
!
interface GigabitEthernet0/1.6
encapsulation dot1Q 6
pppoe enable group global
pppoe-client dial-pool-number 1
!
interface GigabitEthernet0/1.999
encapsulation dot1Q 999 native
!
interface Dialer0
ip address negotiated
ip mtu 1492
ip nat outside
ip virtual-reassembly
encapsulation ppp
ip tcp adjust-mss 1452
dialer pool 1
dialer idle-timeout 0
dialer-group 1
ppp authentication pap callin
ppp pap sent-username xxxxx@xxxxx password 7 xxxxxx
ppp ipcp route default
no cdp enable
!
!
ip forward-protocol nd
no ip http server
no ip http secure-server
!
!
ip route 0.0.0.0 0.0.0.0 Dialer0
!
10-08-2013 04:53 AM
Hello again,
this morning I have tried to change the pseudowire-class:
pseudowire-class PSVLANS
encapsulation l2tpv3
protocol l2tpv3 class1
ip local interface Loopback1000
ip pmtu max 1400
ip dfbit set
!
The problem is the same. The performance is very bad (or it does not work) when I try to visit a web site.
I am very surprised by poor performance of c7200 (NPEG1) in this kind of tunneling. Besides the only
solution I see is change the MTU in all hosts. We are going to use GRE tunnels (L3 connections) because
we can use ip tcp mss adjust command.
I don't think that none has the same problem
Thanks.
Regards.
10-08-2013 05:00 AM
Hi Antonio,
Have you tried putting the adjust-mss command on the ingress Gigabit interface (the interface towards the hosts) and see if that makes a difference?
10-08-2013 05:33 AM
Hello,
yes i did it. The problem is that the interface encapsulate traffic without change the MSS. I have tried
3 different IOS. I think that if you use the xconnect command the adjust-mss command has no effect.
Thanks any way.
Regards.
10-08-2013 03:18 PM
Hello again,
I need a L2 tunnel over a comercial FTTH connection that use pppoe. I have used L2TPv3 and now EoMPLS over GRE.
I know that L2TPv3 can fragment the packets automatically but as I have said the performance in a NPG1 c7200 is
not very good (5-10Mbps). If I configured the MTU in the host the performance is better (20-30Mbps).
In theory PMTU should work but everybody knows that ICMP packets can be filtered. So some web sites are
very slow.
Now I have tried EoMPLS over GRE. The problem is the same. I need to reduce the MTU in the host. I do not know the
performance in a real c7200 .I can not increase MTU in the CORE links because is a remote site that using a comercial connection.
I can't understand why "ip tcp adjust-mss" does not work. Well I know that the xconnect is before TCP inspection so
the router does not change the MSS in the TCP SYNC packet. This can not be considered as a bug but I think can
be considered as a interesting feature in this scenarios (can some people cisco tell something about it?).
Finally, there is any others solutions for a L2 connection through a comercial (DSL, FTTH,...) connection without
changing any paremeter in the hosts?.
Thanks in advanced.
Regards.
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