11-17-2007 10:46 PM
Hi Guys,
i got a situation here and hope someone will be able to help me out. Recently i configured a PPP multilink and am facing some issues after that.
Issue 1:
There seems to be lot of input error on multilink interface (150 errors in 40 mins)
Issue 2:
when any of the multilink member interface goes down (all other links are active), am getting packrt drops and request timed out when i ping my other end multi link interface atleast for some 30 sec , after which my response is ok.
About my network
I have connectivity between site A and Site B which consists of five 64 kbps Leased lines bundled together with Multilink PPP
My configuration is shown below
End A
interface multilink 1
ip address x.x.x.x x.x.x.x
ppp multilink fragment-delay 20
ppp multilink interleave
ppp multilink
multilink-group 1
int Ser 2/0
bandwidth 64
no ip address
no ip redirects
no ip proxy-arp
encapsulation ppp
no ip route-cache
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
int Ser 2/1
bandwidth 64
no ip address
no ip redirects
no ip proxy-arp
encapsulation ppp
no ip route-cache
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
int Ser 2/2
bandwidth 64
no ip address
no ip redirects
no ip proxy-arp
encapsulation ppp
no ip route-cache
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
int Ser 2/3
bandwidth 64
no ip address
no ip redirects
no ip proxy-arp
encapsulation ppp
no ip route-cache
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
int Ser 2/4
bandwidth 64
no ip address
no ip redirects
no ip proxy-arp
encapsulation ppp
no ip route-cache
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
End B
interface multilink 1
ip address ip address x.x.x.x x.x.x.x
ppp multilink fragment-delay 20
ppp multilink interleave
ppp multilink
multilink-group 1
interface S 2/0:1
bandwidth 64
no ip address
no ip redirects
no ip proxy-arp
encapsulation ppp
no ip route-cache
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
interface S 2/0:11
bandwidth 64
no ip address
no ip redirects
no ip proxy-arp
encapsulation ppp
no ip route-cache
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
interface S 2/0:25
bandwidth 64
no ip address
no ip redirects
no ip proxy-arp
encapsulation ppp
no ip route-cache
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
interface S 2/0:4
bandwidth 64
no ip address
no ip redirects
no ip proxy-arp
encapsulation ppp
no ip route-cache
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
interface S 2/0:6
bandwidth 64
no ip address
no ip redirects
no ip proxy-arp
encapsulation ppp
no ip route-cache
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
11-18-2007 08:04 AM
Hi,
1. Which kind of errors, and do you have errors on physical interfaces ? Send the full show interface if in doubts.
2. do you loose link member frequently enough for this to be a problem? You can try changing the keepalive setting under interface.
11-18-2007 07:39 PM
pls find the output of show command
END A #sh int multilink 5
Multilink5 is up, line protocol is up
Hardware is multilink group interface
Description: ***Multilink to End B ***
Internet address is 192.26.0.162/30
MTU 1500 bytes, BW 320 Kbit, DLY 100000 usec,
reliability 255/255, txload 2/255, rxload 1/255
Encapsulation PPP, loopback not set
Keepalive set (10 sec)
DTR is pulsed for 2 seconds on reset
LCP Open, multilink Open
Open: IPCP, CDPCP
Last input 00:00:00, output never, output hang never
Last clearing of "show interface" counters 19:55:13
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 2000 bits/sec, 4 packets/sec
5 minute output rate 3000 bits/sec, 4 packets/sec
309478 packets input, 58763590 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
1492 input errors, 0 CRC, 1492 frame, 0 overrun, 0 ignored, 0 abort
290606 packets output, 32728691 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
END A #sh ppp multilink
Multilink5, bundle name is End B
Bundle up for 22:06:31
493 lost fragments, 162050 reordered, 0 unassigned
999 discarded, 0 lost received, 3/255 load
0xAE5E6 received sequence, 0x69F6B sent sequence
Member links: 5 active, 0 inactive (max not set, min not set)
Se2/0, since 20:07:34, last rcvd seq 0AE5E1, 160 weight, 152 frag size
Se2/2, since 20:04:45, last rcvd seq 0AE5E2, 160 weight, 152 frag size
Se2/3, since 20:04:07, last rcvd seq 0AE5E3, 160 weight, 152 frag size
Se2/5, since 20:03:24, last rcvd seq 0AE5E4, 160 weight, 152 frag size
Se2/1, since 19:57:12, last rcvd seq 0AE5E5, 160 weight, 152 frag size
Am getting 1400 input errors in last 19 hours on multilink interface, also less than 100 input errors on member serial interfacs.Also am not loosing any link member.
11-19-2007 01:20 AM
Input errors are often due to line issues or incorrect grounding. You may check the latter yourself. Also, make sure that a single line does cause the majority of the errors. For other bit-error issues you will often need to consult your provider.
The problem with multilink is that losing one fragment renders the whole packet invalid so that it must be retransmitted. Also, multilink is quite cpu-intensive.
You might be better off using HDLC or PPP without multilink encapsulation and equal cost load balancing with OSPF.
regards,
Leo
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