02-21-2013 08:54 AM - edited 03-04-2019 07:06 PM
Hi I have an old Cisco 3640 with 5 T1s in a MLPPP bundle.
I've been reading around that with the BW of 5 T1s, I don't need to turn on Interleaving and Fragmentation.
However, there is VoIP traffic going over this bundle as well, I do notice that occasionally I'm seeing jitter on VoIP calls.
Though the jitter seems to manifest itself when the out usage approaches 3-4Mb while the in usage is around 6Mb.
Could this be a CPU issue? Or is it most likely large packets delaying the small voip packets.
I was having more jitter when interleaving and fragmentation were turned on...
Here are relevant parts of the current config:
policy-map voip_policy
class voice
priority 850
class voice-signaling
bandwidth 64
class class-default
fair-queue
interface Multilink13701
ip unnumbered Loopback0
ppp multilink
ppp multilink fragment disable
ppp multilink group 13701
ppp multilink endpoint ip 10.1.1.1
service-policy output voip_policy
interface Serial0/0
no ip address
encapsulation ppp
ppp multilink
ppp multilink group 13701
etc...
02-21-2013 08:57 AM
5x T1 in MLPPP on an old tired 3640 is betting on luck anough already, add interleaving and fragmenation, chances or success with some performance left are next to zero.
02-21-2013 09:30 AM
Yeah, I was afraid of that.
What can handle 5 T1s that's fairly current short of going to a 7200 chassis?
02-21-2013 09:43 AM
Upgrade to ethernet-based services, you will save money and trouble.
02-21-2013 10:10 AM
Yes of course that's optimal, but at this location I cannot at the present time.
02-21-2013 11:28 AM
Then keep struggling, because no matter the platform, MLPPP is the worst WAN technology of any.
02-21-2013 10:59 AM
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You shouldn't need interleaving/fragmentation if link bandwidth > half T1.
Try setting tx-ring-limit to minimal value on all your serial interfaces.
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