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many lost fragments on ppp-multilink connections

g.thuemmler
Level 1
Level 1

Hi,

here works many E1-connectoins (PRI dial-connectoins) from different

routers (3620 or 26xx) with e1 interfaces to AS5400 (with only e1) and

an C7509 with e1-interfaces.

For many routers that works properly but on some whe have many problems

with the performance. In the output for show ppp multlink, i can see on

this routers many lost fragments. Have you some tips for me?

Here is a smpleconfig:

ROUTER-BeschA#sh run

Building configuration...

Current configuration : 1571 bytes

!

version 12.2

service timestamps debug datetime msec localtime show-timezone

service timestamps log datetime msec localtime show-timezone

service password-encryption

!

hostname ROUTER

!

username cisco1 password xyz

username dallas password xyz

memory-size iomem 30

clock timezone UTC 1

clock summer-time MESZ recurring last Sun Mar 2:00 last Sun Oct 2:00

ip subnet-zero

no ip gratuitous-arps

ip cef

!

!

no ip domain-lookup

!

isdn switch-type primary-net5

!

controller E1 1/0

pri-group timeslots 1-31

!

!

!

interface Loopback10

ip address 10.1.2.3 255.255.255.255

!

interface Ethernet0/0

ip address 10.0.1.1 255.255.255.0

half-duplex

no cdp enable

!

interface Serial1/0:15

ip unnumbered Loopback10

encapsulation ppp

no ip route-cache cef

ip mroute-cache

no logging event link-status

load-interval 30

dialer enable-timeout 6

dialer wait-for-carrier-time 5

dialer string 1

dialer hold-queue 100

dialer load-threshold 80 either

dialer-group 1

isdn switch-type primary-net5

ppp authentication chap

ppp multilink

ppp multilink interleave

ppp timeout multilink link remove 20

!

ip classless

ip route 10.0.0.0 255.0.0.0 Serial1/0:15

no ip http server

!

dialer-list 1 protocol ip permit

snmp-server community XXX RO

snmp-server enable traps tty

!

line con 0

exec-timeout 0 0

line aux 0

line vty 0 4

password xyz

login

!

ntp server 10.9.8.7

end

and an show ppp multilink

ROUTER#sh pp mu

Virtual-Access1, bundle name is dallas

Bundle up for 2d22h

Dialer interface is Serial1/0:15

14233 lost fragments, 1283236 reordered, 0 unassigned

31045 discarded, 509 lost received, 78/255 load

0x377D9E received sequence, 0x228CC8 sent sequence

Member links: 12 (max not set, min not set)

Se1/0:26, since 2d22h, last rcvd seq 377D96, 240 weight, 232 frag size

Se1/0:23, since 2d22h, last rcvd seq 377D9A, 240 weight, 232 frag size

Se1/0:24, since 2d22h, last rcvd seq 377D9B, 240 weight, 232 frag size

Se1/0:12, since 2d22h, last rcvd seq 377D9C, 240 weight, 232 frag size

Se1/0:2, since 2d22h, last rcvd seq 377D9D, 240 weight, 232 frag size

Se1/0:30, since 00:02:08, last rcvd seq 377D8A, 240 weight, 232 frag

size

Se1/0:29, since 00:01:53, last rcvd seq 377D8B, 240 weight, 232 frag

size

Se1/0:28, since 00:00:46, last rcvd seq 377D95, 240 weight, 232 frag

size

Se1/0:27, since 00:00:34, last rcvd seq 377D8D, 240 weight, 232 frag

size

Se1/0:25, since 00:00:18, last rcvd seq 377D8E, 240 weight, 232 frag

size

Se1/0:22, since 00:00:12, last rcvd seq 377D8F, 240 weight, 232 frag

size

Se1/0:21, since 00:00:06, last rcvd seq 377D90, 240 weight, 232 frag

size

thx for any tips

Gerd Thuemmler

Germany

Sorry for my bad english, but its so long that learn it in scool

1 Reply 1

Hello Gerd,

the lost fragments might be due to idle links. Just for testing purposes, can you remove the ´ppp timeout multilink link remove 20´ from your configuration and set the minimum member links to 12 (the actual maximum) ?

Also, check out this link for a very detailed explanantion of fragment loss (have a look at chapter 4 of this document):

http://rfc.sunsite.dk/rfc/rfc1990.html

Regards,

Georg

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