The MPLS-OPS Archive

[Abhishek Mittal <ask4mpls@yahoo.com>]

Hi Garry,

 

What do you mean by Dialup (DSL) customers.

 

As per your network diagram , your DSL customers are getting connected on Cisco 2900 switch & this L2 switch is connected to your PE3.

 

Kindly expedite it once.I think i am missing some thing to understand it.

 

Thanks & Regards

Abhishek Mittal

Garry Glendown <garry@regio.net> wrote:

> Abhishek Mittal wrote:
> > Hi Garry,
> > 
> > Can you please tell us the below information to understand your problem 
> > and for troubleshooting :
>
> OK, preliminarily it looks like it is mostly working now - I changed all 
> the MTUs on the way back to 1500 (except on the switches) but altered 
> the "mpls mtu" to 1520 ... everything seems to work ... EXCEPT now I've 
> run into problems with some regular DSL dialups ...
>
> > 1> Your customer is connected on DSL ?
>
> The original problem - no, the problem occurred on our regular leased 
> lines, mainly the before mentioned ethernet bridge ...
>
> > 2> Do you use PPPoE or PPPoA or static in case of DSL connection ?
> > 3> What kind of bridge is it? Is it Ethernet based or USB ?
>
> No, it's a leased line from German Telekom T-Com, with FE link on both 
> sides, which!
>   I have
>  connected to the router via a 29series switch (all 
> Cisco)
>
> > 4> Which OS you use at your customer PC ?
>
> any - problem had occurred with both Linux and Windows ...
>
> > 5> in case of DSL , wht is your BRAS function?
> > 6> What media do you have (means from BRAS to CPE , in case of DSL tech)
> > 7> WHich DSLAM do you use ?
>
> doesn't apply in the original case ...
>
> Anyway, now that THAT seems to be fine w/ above fix, another place is 
> giving me problems ...
>
> Getting back to the original drawing:
>
> +------SWITCH-----+
> | | |
> Uplink----PE1 PE2 PE3-----Customer Dialup (DSL)
> / |
> PEERING | Backbone
> |
> PE5-----P1-----Switch
> | |
> | E3 | FE-Bridge
> | |
> PE6--P2--PE4-----Switch
> |
> CE
>
> (Routers PE1-4 and P1 have MPLS enabled)
>
> While I have no MTU problems e.g. in the ethernet at P2 (not in the MPLS 
> cloud), which I previously had when the FE bridge was giving me 
> troub!
>  les,
>  something different has come up - customers dialing up at PE3 
> via DSL (with MTUs of 1456:
>
> dsl-gw.ffm#show int vi25 conf
> Virtual-Access25 is an VPDN link (sub)interface
>
> Derived configuration : 371 bytes
> !
> interface Virtual-Access25
> mtu 1456
> ip unnumbered FastEthernet0/0
> rate-limit input 128000 7500 7500 conform-action continue 
> exceed-action drop
> rate-limit output 1048000 7500 7500 conform-action continue 
> exceed-action drop
> ip tcp adjust-mss 1416
> timeout absolute 1440 0
> peer default ip address pool dsl-pool
> keepalive 60
> ppp authentication chap pap callin
> end
> )
>
> are now having problems connecting to the web/ftp server on the ethernet 
> behind P1/PE5, which they never had before switching to MPLS ... I 
> tested with the first customer that reported it (he's running a Linux 
> proxy) - adjusting the MTU on that machine to 1400 fixed the problem for 
> him. Anyway, as we soon got the next call from an!
>  other
>  customer where I 
> couldn't do that fix, I tried adjusting the web server's MTU to 1400 and 
> tested again with the first customer, re-setting his MTU to 1500 - still 
> worked there, though I have no report from the seconds customer as to 
> whether it is working for him again. I had also tried setting the 
> adjust-mss to something smaller, like 1400, but that didn't help ... 
> what is going on here? Needless to say, both customers did not have any 
> problems connecting to external servers (behind uplinks/peerings), nor 
> did I have any problems connecting from e.g. the P2 ethernet to the same 
> server ...
>
> Tnx, -gg
>
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