[j-nsp] MTU/MRU issues on ERX-310 (LNS)

Goldschmidt, Bernd bernd.goldschmidt at siemens.com
Fri Jan 20 12:30:45 EST 2006


Hi Andy,

normaly the ip tcp adjust-mss will solve all MTU problems in a LNS setup (for TCP packets).
This was first developed for an ERX running as a LNS.

You can try to change the profile to:
-------------------------------------
profile "profilename"
 ip unnumbered loopback 0
 ip sa-validate
 ppp mru 1442
 ppp authenticate pap
 ip tcp adjust-mss 1400

or:
---
profile "profilename"
 ip unnumbered loopback 0
 ip sa-validate
 ppp mru 1442
 ppp authenticate pap
 ip tcp adjust-mss 1400
 ip ignore-df-bit


The ppp mru setting is only helpful when the CPE negotiates/accept the value.
In case of the with www.hotmail.com what MRU was negotiated?

lydia#sh subscribers username bwg at tunnel.com
                             Subscriber List
                             ---------------
                                                            Virtual
       User Name           Type         Addr|Endpt           Router
------------------------   -----   --------------------   ------------
bwg at tunnel.com              ppp     172.254.101.25/local   default
       User Name                      Interface
------------------------   --------------------------------
bb at tunnel.com              l2tp 1/1/621771

lydia#sh ppp interface TUNNEL l2tp:1/1/621771 full
PPP interface TUNNEL l2tp:1/1/621771 is up
Interface administrative status is open
Configured network protocol is IPCP
IPCP protocol configuration
   configured                     true
   administrative-status          open
   ip-address                     x.x.x.x
   dns-precedence                 local
   wins-precedence                local
   ipcp-netmask-option            disabled
IPCP protocol status
   operational-status             up
IPCP negotiated options           local               peer
   ip-address                     x.x.x.x             172.254.107.26
   ip-address-mask                none                none
   primary-dns-address            none                none
   secondary-dns-address          none                none
   primary-wins-address           none                none
   secondary-wins-address         none                none
IPV6CP protocol configuration
   configured                     false
   administrative-status          open
   ipv6-interfaceId               0:0:0:0
IPV6CP protocol status
   operational-status             not present
OSINLCP protocol configuration
   configured                     false
   administrative-status          open
OSINLCP protocol status
   operational-status             not present
Interface statistics              in                   out
   packets                        0                    0
   octets                         155                  159
   errors                         0                    0
   discards                       0                    0
LCP protocol configuration
   max-receive-unit               1442            <----------------------------------------
   authentication                 pap/chap
   magic-number                   enabled
   keepalive-timer                30 seconds
   restart-timer                  3 seconds
   max-terminate                  2
   max-configure                  10
   max-failure                    5
   passive-mode                   disabled
LCP protocol status
   link-status                    network
LCP negotiated options            local               peer
   max-receive-unit               1442                1442  <------------------------------
   authentication                 pap                 none
   magic-number                   0x71f0770e          0x5768caf4
   accm                           none                none
   pfc                            none                none
   acfc                           none                none
LCP protocol statistics
   in-keepalive-requests          3
   out-keepalive-requests         3
   in-keepalive-replies           3
   out-keepalive-replies          3
   keepalive-failures             0
Authentication configuration
   authenticate-retry             0
   authentication-router          ''
   aaa-profile                    ''
Authentication status
   grant                          true
   session-timeout                31622400 seconds
   inactivity-timeout             none
   accounting-timeout             none
   peer-ip-address                172.254.107.26
   peer-ip-address-mask           none
   peer-primary-dns-address       x.x.x.x
   peer-secondary-dns-address     x.x.x.x
   peer-primary-wins-address      none
   peer-secondary-wins-address    none
   peer-ipv6-interface-id         none
Authentication statistics
   up-time                        272 seconds
   in-octets                      96
   out-octets                     96
   in-packets                     0
   out-packets                    0
PAP protocol configuration
   request-timeout                20 seconds
CHAP protocol configuration
   name                           ''
   challenge-retry                10
   challenge-timeout              4 seconds
   minimum-challenge-length       16
   maximum-challenge-length       32
   minimum-rechallenge-timeout    0 seconds
   maximum-rechallenge-timeout    0 seconds
lydia#





2 1/2 days???
Which JTAC?


Gruß
Bernd.

 

> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net 
> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of 
> Andy Lamontagne
> Sent: Thursday, January 19, 2006 3:07 AM
> To: juniper-nsp at puck.nether.net
> Subject: [j-nsp] MTU/MRU issues on ERX-310 (LNS)
> 
> Hey everyone,
> 
> I've been trying for more than 3 days to get our ERX-310 
> (LNS) in service.
> After 2 1/2 days troubleshooting with JTAC, we were finally 
> able to bring up
> the session (L2TP).
> 
> Now that we can connect and get an IP from RADIUS, we are 
> running into a MTU
> and/or MRU issue.
> 
> According to documentation (and JTAC) we should only need to inlcude
> 
> ppp mru 1442
> 
> in our profile.
> 
> The setup looks like this
> 
> ==============================================================
> ==========
> l2tp destination profile "profile_name" virtual-router 
> "virtual_router_name"
> ip address 10.x.x.x
> remote host "remotehostname"
>  profile "profilename"
> local host "localhostname"
> local ip address 10.x.x.x
> disable proxy lcp
> enable proxy authenticate
> 
> profile "profilename"
> ip unnumbered loopback 0
> ip sa-validate
> ppp mru 1442
> ppp authenticate pap
> 
> ==============================================================
> ==========
> 
> When connected via PPPoE (software or xDSL/router modem) we 
> are unable to
> access many sites (ex: www.hotmail.com) and use the MSN 
> Messanger client.
> 
> We've tried different configurations (ex: setting MTU to 
> different values,
> MRU to different values as well as "ip tcp adjust-mss" to 
> different values)
> and no luck.
> 
> We also have "ip tunnel reassembly" enable on the router.
> 
> We do not have access to the LAC, but we do have a Cisco 
> Router as an LNS
> working without a problem.
> 
> We have tried to mirror the config from our existing / 
> functioning Cisco
> LNS, but have had no luck.
> 
> Has anyone had any experience setting up an ERX as an LNS 
> connecting to
> another ERX ( - 1410- LAC) ...
> 
> Any suggestions welcome!
> 
> Thanks
> 
> Andy
> _______________________________________________
> juniper-nsp mailing list juniper-nsp at puck.nether.net
> http://puck.nether.net/mailman/listinfo/juniper-nsp
> 



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