Cisco 2900 router DHCP issue with Polycom Lync Phone

[Yogeswaran Nadesu]

We have strange DHCP  issue with Polycom-VVX Lync phones using C2900 DHCP server.

DHCP configuration works with Cisco 2800 router, but same dhcp configuration doesn't work with C2900 router.

Only difference, Cisco 2800 router accepts option 43 without "EXT" word. But in C2900, we need to add option ext 43 hex

See below the voice vlan dhcp pool for C2900

ip dhcp pool MQT-L8-Lync-Phones
 network 172.22.12.0 255.255.255.0
 next-server 10.82.20.50
 default-router 172.22.12.1
 dns-server 10.82.10.250 10.18.15.39
 option 42 ip 10.82.10.250
 domain-name govnet.nsw.gov.au
 option 160 ascii ftp://ausvwlyncmed01.nswgov.ucfx.com
 option ext 43 hex 010c.4d53.2d55.432d.436c.6965.6e74.0205.6874.7470.7303.1a6c.796e.6370.6f6f.6c30.312e.6e73.7767.6f76.2e75.6366.782e.636f.6d04.0334.3433.0525.2f43.6572.7450.726f.762f.4365.7274.5072.6f76.6973.696f.6e69
 option ext 43 hex 6e67.5365.7276.6963.652e.7376.63
 

[Hamos5789]

I also had the same issue than youon C2900 but I I solved the problem by configuring the dhcp on the Switch that has no character limit

c2960

ip dhcp pool TELEFONIA_LYNC
 network x.x.x.x.x x.x.x.x.x
 option 43 hex 010c.4d53.2d55.432d.436c.6965.6e74.0205.6874.7470.7303.166c.796e.6370.6f6f.6c2e.7373.662e.766f.786e.732e.636f.6d04.0334.3433.0525.2f43.6572.7450.726f.762f.4365.7274.5072.6f76.6973.696f.6e69.6e67.5365.7276.6963.652e.7376.63
 default-router 10.x.x.x 
 domain-name bancolombia.corp
 option 2 hex ffff.b9b0
 option 4 ip 10.x.x.x
 option 42 ip 10.x.x.x
 option 119 hex 0b62.616e.636f.6c6f.6d62.6961.0463.6f72.7000
 option 10 hex 0011
 option 60 ascii "CPE-OCPHONE"
 option 120 hex 000a.6c62.6d64.6562.6c73.3031.0b62.616e.636f.6c6f.6d62.6961.0463.6f72.7000
 dns-server x.x.x.x