PPP Multilink revisited...Assistance needed

L0man · Guest

Somehow, my first post was buried underneath a post started back in
2001! So, at the risk of flames, I am posting it again, so here goes:

I have a strange situation. I am connecting a 7206VXR to a 7507 via
MPPP over 2 T1 leased lilnes. In my test lab, I used another 7206 to
simulate the 7507 (prouduction box) with both back-to-back cables and
across the T1s themselves and had no problems. But, when I connect
the 7206 to the 7507 I get horrible response times across the link.
Just pinging produces response times of 20ms to 500ms. I worked with
the TAC for a couple of hours last night, but wasn't able to resolve
during my scheduled downtime, so I had to call the thing off.
Here is the pertinent portion of my 7507 config:

no ip cef
ipx routing 000b.45ce.7000
!
controller T1 1/0/0
channel-group 0 timeslots 24
!
controller T1 1/0/1
channel-group 0 timeslots 24
!
controller T1 1/0/2
!
controller T1 1/0/3
!
controller T1 1/0/4
!
controller T1 1/0/5
!
controller T1 1/0/6
!
controller T1 1/0/7
!
controller T1 1/1/0
!
controller T1 1/1/1
!
controller T1 1/1/2
!
controller T1 1/1/3
!
controller T1 1/1/4
!
controller T1 1/1/5
!
controller T1 1/1/6
!
controller T1 1/1/7
!
!
!
!
!
interface Loopback0
ip address 10.192.254.6 255.255.255.255
!
interface Multilink1
ip address 10.192.10.41 255.255.255.252
no ip route-cache
ip ospf message-digest-key 1 md5 xxxxxxxxxx
no ip mroute-cache
ipx network 9B848A1B
no cdp enable
ppp multilink
no ppp multilink fragmentation
multilink-group 1
!
! SNIP
!
interface Serial1/0/0:0
no ip address
encapsulation ppp
no ip route-cache
no fair-queue
ppp multilink
multilink-group 1
!
interface Serial1/0/1:0
no ip address
encapsulation ppp
no ip route-cache
no fair-queue
ppp multilink
multilink-group 1
******************************

Here is the 7206 config:

controller T1 1/0
framing esf
linecode b8zs
channel-group 0 timeslots 24
no yellow generation
no yellow detection
!
controller T1 1/1
framing esf
linecode b8zs
channel-group 0 timeslots 24
no yellow generation
no yellow detection
!
controller T1 1/2
framing esf
linecode b8zs
no yellow generation
no yellow detection
!
controller T1 1/3
framing esf
linecode b8zs
no yellow generation
no yellow detection
!
!
! SNIP
!
interface Loopback0
ip address 10.192.254.11 255.255.255.255
!
interface Multilink1
ip address 10.192.10.42 255.255.255.252
no ip route-cache
ip ospf message-digest-key 1 md5 xxxxxxxxxx
no ip mroute-cache
ipx network 9B848A1B
no cdp enable
no ppp multilink fragmentation
ppp multilink
multilink-group 1
!
! SNIP
!
interface Serial1/0:0
no ip address
encapsulation ppp
no ip route-cache
no fair-queue
ppp multilink
multilink-group 1
!
interface Serial1/1:0
no ip address
encapsulation ppp
no ip route-cache
no fair-queue
ppp multilink
multilink-group 1

Cisco had me add the "no ip route-cache" ,"no ip mroute-cache", and
"no ppp multilink fragmentation" commands while trying to fix the
problem.

Thanks in advance for any suggestions.

L0man · Guest

I think I may have found part of the problem, and I knew better. The
"channel-group 0 timeslots 24" should have been "channel-group 0
timeslots 1-24".
Thanks to Will, who pointed this error out to me via email.

One other thing. To the fellow who posted under my previous
"Multilink PPP Question" thread below: I had a problem when I first
connected my 7206 to the 7507, the 7206 kept crashing and reloading.
According to the TAC, there is a bug that affects most current
versions of code involving MPPP and the 7206, and, at this time, there
is no fix, but a workaround is available: Be sure to include "no
fair-queue" under the serial interfaces. This is pretty standard for
this type of config, but I had forgotten to use it. I noticed that it
is added by default on the 7507, but not on the 7206. At least, that
has been my experience.

Thanks to everyone for their assistance.

Brian Lehigh · Guest

Thanks for the info. Should the "no fair-queue" be added to the "Multilink"
interface or to the Serial interfaces (or both)? I'm assuming the "no
fair-queue" is the workaround you were speaking of.
Thanks,

-Brian

"L0man" <f00f1ter@yahoo.com> wrote in message
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Brian Lehigh · Guest

Well, I'm not sure what I did wrong but I couldn't get the multilink bundle
to come up this morning. After configuring everything the serial links were
added to the multilink bundle but if I did a "show ppp multilink" the status
showed as inactive and "show interface multilink1" showed as up/down. I
didn't specify any dialer-groups, etc. so it seems like the bundle should
just come up.
Any thoughts on why this would happen?

-Brian

"Brian Lehigh" <brianl@sti.net> wrote in message
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