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New Member

Multiple PPP Multilinks in 7609 router

We have Cisco 7609 routers in our network. We are using ppp multilinks between the sites. Because of the high traffic volume, we have to use multiple multilinks. 7609 router doesn't allow ppp multlink to span SIPs, so we use multiple mulitilinks between sites on different SIPs. OSPF for load balancing will be used. THE PROBLEM IS: when we define the second ppp multilink between two 7609 routers, the new multilink stays "inactive". Can we use multiple multilinks to the same router? We have enabled the command IP CEF DISTRIBUTED, but we still face the same problem". IOS used is: 122-18.SXF6

1 ACCEPTED SOLUTION

Accepted Solutions
New Member

Re: Multiple PPP Multilinks in 7609 router

Multilink needs to identify how to differentiate between bundles, this said if you use more than one multilink on a router you need to identify the member links of the bundle. When "not" using authentication the next method is to use an endpoint dicriminator for the serial links to facilitate the bundle identification by the local router. Endpoint discriminators are locally specific to the router so if each serial port is assigned to an individual multilink bundle then use unique endpoint discriminator values for each serial link, no need to make them match on source and target router. If more than one interface is assigned to the same multilink bundle they must have the same endpoint discriminator value. Long winded but here is the example from your posting, a bit shortened for reading ease.

interface Serial 2/0/0:1

encapsulation ppp

ip route-cache cef

ppp multilink

multilink-group 122

ppp multilink endpoint string multi122

interface Serial 2/0/1:1

encapsulation ppp

ip route-cache cef

ppp multilink

multilink-group 122

ppp multilink endpoint string multi122

When each link is assigned to an individual multilink bundle the discriminator values need to be different, have used this just to take advantage of LFI and allow the routing protocol do the load balancing.

Cheers,

Brian

21 REPLIES

Re: Multiple PPP Multilinks in 7609 router

Hi

Can you post the configs related to multilink and physical link config binded to the same ?

Also can you post the outputs of show ip int brief and show interface multilink ?

regds

New Member

Re: Multiple PPP Multilinks in 7609 router

Hello,

Thanks for your response, i removed some of the sh ip int breif coz i exceeded the max limit,

rgds

interface Multilink 122

bandwidth 4000

ip address 192.168.2.34 255.255.255.252

encapsulation ppp

no ip directed-broadcast

no ip proxy-arp

no ip redirects

no ip mroute-cache

ip route-cache

ppp multilink

multilink-group 122

interface Serial 2/0/0:1

no ip address

encapsulation ppp

no ip directed-broadcast

no ip proxy-arp

no ip redirects

no ip mroute-cache

ip route-cache cef

ppp multilink

multilink-group 122

interface Serial 2/0/1:1

no ip address

encapsulation ppp

no ip directed-broadcast

no ip proxy-arp

no ip redirects

no ip mroute-cache

ip route-cache cef

ppp multilink

multilink-group 122

7609#sh pp mu

Multilink26, bundle name is RTR-7609

Bundle up for 2d04h

Bundle is Distributed

5529 lost fragments, 38369916 reordered, 6 unassigned

14 discarded, 14 lost received, 83/255 load

0x3C98EA received sequence, 0xF6893A sent sequence

Member links: 5 active, (max not set, min not set)

Se1/1/1:1, since 2d04h, no frags rcvd

Se1/0/1:1, since 2d04h, no frags rcvd

Se1/0/2:1, since 2d04h, no frags rcvd

Se1/0/0:1, since 1d07h, no frags rcvd

Se1/1/0:1, since 04:46:34, no frags rcvd

Multilink7, bundle name is RTR2-7609

Bundle up for 1w1d

Bundle is Distributed

0 lost fragments, 0 reordered, 0 unassigned

0 discarded, 0 lost received, 24/255 load

0x0 received sequence, 0x876730 sent sequence

Member links: 3 active, 0 inactive (max not set, min not set)

Se3/0/2:1, since 1w1d, no frags rcvd

Se3/0/1:1, since 12:28:52, no frags rcvd

Se3/0/0:1, since 12:28:52, no frags rcvd

Distributed fragmentation on. Fragment size 512. Multilink in Hardware.

Multilink6, bundle name is RTR3-7609

Bundle up for 2w3d

Bundle is Distributed

951 lost fragments, 649515071 reordered, 6 unassigned

97 discarded, 98 lost received, 86/255 load

0xBA15B9 received sequence, 0x2E367B sent sequence

Member links: 8 active, 0 inactive (max not set, min not set)

Se1/1/4:1, since 2w3d, no frags rcvd

Se1/1/5:1, since 2w3d, no frags rcvd

Se1/3/5:1, since 2w3d, no frags rcvd

Se1/3/4:1, since 2w3d, no frags rcvd

Se1/0/4:1, since 2d13h, no frags rcvd

Se1/0/5:1, since 2d13h, no frags rcvd

Se1/2/4:1, since 00:28:04, no frags rcvd

Se1/2/5:1, since 00:28:10, no frags rcvd

Multilink122 (inactive)

Member links: 2

Se2/0/0:1 (inactive)

Se2/0/1:1 (inactive)

sh inter mu 122

Multilink122 is down, line protocol is down

Hardware is multilink group interface

Description: Multilink ISB to Multilink LHR

Internet address is 192.168.2.34/30

MTU 1500 bytes, BW 4000 Kbit, DLY 100000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation PPP, loopback not set

Keepalive set (10 sec)

DTR is pulsed for 2 seconds on reset

LCP Closed, multilink Closed

Closed: CDPCP, IPCP

Last input never, output never, output hang never

Last clearing of "show interface" counters 19:17:44

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 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts (0 IP multicasts)

0 runts, 0 giants, 0 throttles

501 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

0 packets output, 0 bytes, 0 underruns

0 output errors, 0 collisions, 3 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

Re: Multiple PPP Multilinks in 7609 router

Hi

Can you post the output of both show interface serial 2/0/0:1 and serial 2/0/1:1 ?

I feel both your serial links are down which in turn affects the status of your multilink..

regds

New Member

Re: Multiple PPP Multilinks in 7609 router

they show up down when added to the multilink

but show up up when removed from the multilink

and by the way, we have faced this same problem twice i.e 4 different 7609 routers

I am afraid this is a HW limitation

rgds

Silver

Re: Multiple PPP Multilinks in 7609 router

According to below link. Are you using PPP authentication for the MLPPP ? If yes, you have to use different username for different MLPPP bundles.

http://www.cisco.com/en/US/tech/tk713/tk507/technologies_configuration_example09186a0080093c1d.shtml

Hope this helps.

New Member

Re: Multiple PPP Multilinks in 7609 router

Thanks for your response

We are not using authentication

Regards,

Re: Multiple PPP Multilinks in 7609 router

What's there at the far end to this box. Is that also configured for MLPPP.Your both the sides should be configured for MLPPP.

Paste the config frrm far end device.

What if you take the Multilink config out of the interface, does this become up/up.

-amit singh

Re: Multiple PPP Multilinks in 7609 router

check status of serial interface Se2/0/0:1 and Se2/0/1:1 as they are are member of this multilink?

As both members are shown as inactive, I doubt that serial interfaces are UP.

Multilink122 (inactive)

Member links: 2

Se2/0/0:1 (inactive)

Se2/0/1:1 (inactive)

make sure, first your individual interfaces on both ends are up, "serial is up, line protocol is up", only then multilink will come UP.

New Member

Re: Multiple PPP Multilinks in 7609 router

Thanx

As I mentioned in my last post, both serials show up up, but when added to the multlink they show up down

rgds

New Member

Re: Multiple PPP Multilinks in 7609 router

Thanks.

Another 7609 router on the other end with exactly the same configuration

if i remove the multilink config, the serial inter shows up up

rgds

Re: Multiple PPP Multilinks in 7609 router

Hi

Can you try shutting and enabling the serial as well multilink interfaces using shut & no shut commands under the serial/multilink interface on both the ends?

We did face similar kinda erratic problems with multilink in 7206 routers which got recited by issuing shut/no shut commands.

regds

New Member

Re: Multiple PPP Multilinks in 7609 router

I did , still the same

below the o/p of one serial after added to the multilink

sh inter serial 2/0/0:1

Serial2/0/0:1 is up, line protocol is down

Hardware is SPA-8XCHT1/E1

MTU 1500 bytes, BW 1984 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation PPP, crc 16, loopback not set

Keepalive set (10 sec)

LCP Listen, multilink Closed

Closed: CDPCP

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 22:48:00

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 10

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

239712 packets input, 4528824 bytes, 0 no buffer

Received 0 broadcasts (0 IP multicasts)

0 runts, 0 giants, 0 throttles

774 input errors, 59 CRC, 306 frame, 0 overrun, 0 ignored, 406 abort

238856 packets output, 4446582 bytes, 0 underruns

0 output errors, 0 collisions, 27927 interface resets

0 output buffer failures, 0 output buffers swapped out

14 carrier transitions no alarm present

Timeslot(s) Used:1-31, subrate: 64Kb/s, transmit delay is 0 flags

Re: Multiple PPP Multilinks in 7609 router

I see a lots of input errors under the serial interface.There are 14 carrier transitions for this interface i.e means interface came up but went down due to some issue.

Please troubleshoot the imput error problem first. It seems like there is some physical link problem. Get on a call with your Telco and troubleshoot the local loop and remote loop checking.

-amit singh

New Member

Re: Multiple PPP Multilinks in 7609 router

Those statistics are kinda old. I can assure you that the media is very clean. Please make note that this problem has been noticed on 4 different E1's

rgds

Silver

Re: Multiple PPP Multilinks in 7609 router

Hi ,

Remove 'encapsulation ppp' from multilink on both ends and check it..

New Member

Re: Multiple PPP Multilinks in 7609 router

Hi,

I remover the encapsulation. Still the multilink shows down down and the serial up down

New Member

Re: Multiple PPP Multilinks in 7609 router

Multilink needs to identify how to differentiate between bundles, this said if you use more than one multilink on a router you need to identify the member links of the bundle. When "not" using authentication the next method is to use an endpoint dicriminator for the serial links to facilitate the bundle identification by the local router. Endpoint discriminators are locally specific to the router so if each serial port is assigned to an individual multilink bundle then use unique endpoint discriminator values for each serial link, no need to make them match on source and target router. If more than one interface is assigned to the same multilink bundle they must have the same endpoint discriminator value. Long winded but here is the example from your posting, a bit shortened for reading ease.

interface Serial 2/0/0:1

encapsulation ppp

ip route-cache cef

ppp multilink

multilink-group 122

ppp multilink endpoint string multi122

interface Serial 2/0/1:1

encapsulation ppp

ip route-cache cef

ppp multilink

multilink-group 122

ppp multilink endpoint string multi122

When each link is assigned to an individual multilink bundle the discriminator values need to be different, have used this just to take advantage of LFI and allow the routing protocol do the load balancing.

Cheers,

Brian

New Member

Re: Multiple PPP Multilinks in 7609 router

Hello Brian,

YOU ARE GREAT, MAN! :-)

As soon as I added the discriminator, the links went up. You really made my day.

Thank youoooooooooooooo

And many thanks for all the guys who particpated in this discussion.

Cheers,

New Member

Re: Multiple PPP Multilinks in 7609 router

hats off Brian

New Member

Re: Multiple PPP Multilinks in 7609 router

Hi !

Have you tried debugging yet ?

Remove the multilink config on the serial interfaces.

Try enabling some of these debugs ..

debug ppp < .. >

authentication CHAP and PAP authentication

bap BAP protocol transactions

compression PPP compression

error Protocol errors and error statistics

mppe MPPE Events

multilink Multilink activity

negotiation Protocol parameter negotiation

packet Low-level PPP packet dump

Then stick the multilink config on the member interfaces and look at what is happenning exactly in the box.

Cheers

Aravind

New Member

Re: Multiple PPP Multilinks in 7609 router

i had the same issue and tried this solution but the problrm still seral links are up----down when it is bundeled inside the multilink interface but it is up---down when it is removed from the multilink interface.

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