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New Member

very low performance on multilinklink E1 bundle


i have configured link bundling on 2 cisco 7200 VXR routers using the "interface multilink" command and succeeded in joining 4 E1 lines into a single 8Mbps pipe. i confirmed the configuration by checking the bandwidth (sh int multilink 1) and the packet counter on each interface after performing a file trancefer test (sh int s0/0:0) where i confirmed that all 4 interfaces are utilized in a round-robin fasion.

here's the thing, when trancefering a 30MB file using FTP between 2 stations (each connected to a router via e0 and the routers are connected via the E1 bundle), the file is trancefered in 6 minutes. this calculates to a trancefer rate of 667Kbps.

why is the transfer rate so slow even though all links a re being used (proven by viewing the packet counter on each serial interface)? what can i do to increase the throughput

NOTE: fragmentation is disabled


VIP Purple

Re: very low performance on multilinklink E1 bundle


you might want to check if you have dCEF enabled on your 7200 routers, I think it is enabled by default on this platform. Otherwise, turn it on with the global command:

ip cef distributed

and make sure that you have the interface configuration statement:

ip route-cache distributed

on all interfaces in your multilink group.



New Member

Re: very low performance on multilinklink E1 bundle

hi again

the cisco 7200 platform does not support dCEF. it does support CEF but that may put more load on the CPU (in addition to the load caused by MLPPP).


Re: very low performance on multilinklink E1 bundle

CEF is OK but in some IOS releases I've encountered CEF adjacency errors on multilink interfaces (I can say with 12.2(15)T it's OK on 7200). In your file transfer test are T1s utilized fully? Because FTP uses TCP, FTP performance relies on TCP performance and this is dependent on TCP stacks of both hosts besides netwrok performance. If it's a lab environement what's transfer rate if you connect two hosts via a switch?


New Member

Re: very low performance on multilinklink E1 bundle


well we got it working now. all along we were trying to fix MLPPP while neglecting that 7200s have ehternet interfaces (10Mbps). after installing 1000BaseFX card and trying the test again, the byte rate sky-rocketed.

i thought if anything, the bottle neck would be at the 8Mbps bundle and not the 10 meg link. i still don't get it though. i need to brush up on my basics i guess.

thanks for your help guys.


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