?
Solved

Multilink ppp Speed Problem

Posted on 2006-05-02
3
Medium Priority
?
464 Views
Last Modified: 2013-12-14

I have a problem when i do multilink ppp to bond 2 dsl lines.

One of the lines is a 2meg SDSL and the other line is a 0.5 meg IP stream ADSL.

the 2meg on its own , runs at 2meg speed when i do a line test, when i run a line test on the 0.5 meg ADSl, i get 0.5meg speed.

When when i run a line test when the 2 lines are part of MLP bundle, i get 1 meg speed.

It doesnt seen to make any sense, when i check the lines on the LNS, i can see they have formed an MPL bundle...so why do i get 1meg speed when the lines are combined as a bundle?

MY config on the cisco router is below.....



!
controller DSL 0/1/0
 mode atm
 line-term cpe
 line-mode 2-wire line-zero
 dsl-mode shdsl symmetric annex B
 line-rate auto
!
!
!
interface FastEthernet0/0
 ip address 192.168.16.1 255.255.255.240
 ip nat inside
 duplex auto
 speed auto
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface ATM0/0/0
 no ip address
 no atm ilmi-keepalive
 dsl operating-mode auto
 pvc 0/38
  encapsulation aal5mux ppp dialer
  dialer pool-member 1
 !
!
interface ATM0/1/0
 no ip address
 no atm ilmi-keepalive
 pvc 0/38
  encapsulation aal5mux ppp dialer
  dialer pool-member 1
 !
!
interface Dialer0
 ip address negotiated
 ip nat outside
 encapsulation ppp
 dialer pool 1
 dialer persistent
 dialer-group 1
 ppp authentication chap callin
 ppp chap hostname xxxxxxxxxxxxxxxx
 ppp chap password 0 test
 ppp multilink
!
ip classless
ip route 0.0.0.0 0.0.0.0 Dialer0
!
!
no ip http server
no ip http secure-server
ip nat inside source list 101 interface Dialer0 overload
!
access-list 101 permit ip 192.168.16.0 0.0.0.15 any
dialer-list 1 protocol ip permit
!
!
!
control-plane
!
!
!

0
Comment
Question by:mbavisi
  • 2
3 Comments
 
LVL 12

Expert Comment

by:pjtemplin
ID: 16589652
Bzzzt...1Mbps is the right answer.

Half the traffic goes onto link 1, half the traffic goes onto link 2.

At 500kbps on link 1 and 500kbps on link 2, the 500kbps link is full.  You won't be able to exceed 1Mbps with this configuration.

For 2.5Mbps, assuming they are private lines and you operate the routers on both ends, you can do EIGRP routing over the links with variance of at least 4 to get unequal-cost load sharing, or you can get real fancy (with fancy hardware) and do MPLS Traffic Engineering, but that's way overkill for your application.
0
 
LVL 1

Author Comment

by:mbavisi
ID: 16603886
nice one pal, can you give me the details of how to set up eigrp to do unequal load sharing.


Many thanks
0
 
LVL 12

Accepted Solution

by:
pjtemplin earned 2000 total points
ID: 16604146
router eigrp XXX
 network x.x.x.x t.t.t.t
 network x.x.x.x t.t.t.t (repeat as needed)
 variance 10
 maximum-paths 6
!

The "variance 10" means once it's found the BEST link(s) (i.e. equal-cost load-sharing), continue considering additional links whose metrics are up to 10x the value of the best link(s) until you've hit the maximum-paths (I think it defaults to 6).  Links are used inversely proportional to their metric, and metric is mostly based on bandwidth in EIGRP.

Two caveats: once the links are selected, their proportions have to be "adjusted" to fit CEF's load-sharing mechanisms.  Per prefix, there are 16 buckets that can be assigned to paths.  In your case, you're hoping for 4/5 over the 2Mb link and 1/5 over the 512k link, but you'll (probably) end up with 13/16 over the 2Mb link and 3/16 over the 512k link, which isn't exactly the split you'd want.  Also, by default FLOWS are divided up over the possible paths based on the CEF proportions, not PACKETS.  If your flows are consistently different enough, you could end up with big-packet flows over one link and small-packet flows over the other link; the flows are distributed as the numbers say, but the bandwidth isn't.  The only way around this, and I do NOT recommend it, is "ip load-sharing per-packet" on both links to do per-packet load-sharing.
0

Featured Post

Granular recovery for Microsoft Exchange

With Veeam Explorer for Microsoft Exchange you can choose the Exchange Servers and restore points you’re interested in, and Veeam Explorer will present the contents of those mailbox stores for browsing, searching and exporting.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Sometimes you have to pull out old tricks to get a new firewall to work… While we were installing a new Sonicwall at a customers site we found that sites they were able to visit before were not working.  It seemed random and we could not understa…
Why do some people recommend buying business VoIP from an ISP? What are the benefits to my company? What are the costs?
Are you ready to place your question in front of subject-matter experts for more timely responses? With the release of Priority Question, Premium Members, Team Accounts and Qualified Experts can now identify the emergent level of their issue, signal…
Loops Section Overview
Suggested Courses

755 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question