Question about ip tcp header-compression

[Yuliang Liang]

my customer have a 3745 router,there is PBX+E1+R3745 in their Lan. customer want to upgrade 3745 to 3845.

but there has a problem when i upgrade to 3845 ,the VOICE lost packet . the voice is ok when i try to "no  ip tcp header-compression iphc-format" on the CLI.

why??

is different ios 12.3 from  12.4??

router 3745

Cisco IOS Software, 3700 Software (C3745-IPVOICE-M), Version 12.3(8)T4, RELEASE SOFTWARE (fc2)

router3845

Cisco IOS Software, 3800 Software (C3845-IPVOICE-M), Version 12.4(24)T5, RELEASE SOFTWARE (fc3)

my configuration:

interface Serial0/0

bandwidth 2048

encapsulation ppp
ip tcp header-compression iphc-format
keepalive 10 3
fair-queue 64 256 16
serial restart-delay 0
ip rtp header-compression iphc-format
ip rtp compression-connections 15
ip rsvp bandwidth 512 32

[paolo bevilacqua]

Update IOS to latest 15.0(1)M

If still trouble, complain to the TAC.

[Yuliang Liang]

thanks for your reply.i will try next time. i had change another method. now the VOIP is OK.

class-map match-any VOICE

match ip dscp cs5

policy-map VOICE

class VOICE

priority percent 30

class class-default

bandwidth percent 70

random-detect

interface Serial0/0

bandwidth 2048

encapsulation ppp
keepalive 10 3

serial restart-delay 0

service-policy output OVICE

[acampbell]

Hi,

Are you sure about this

Usually VOICE (Speech RTP) traffic uses DSCP "EF" = 46 not "CS5" = 40.

May be use class map should be :-

class-map match-any VOICE

match ip dscp ef

Regards

Alex