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SIP Header info missing

Chris Michael

Good day all -

I have an interesting issue. The issue lies in a load balancer (balancing two links). Now the link balancer is not inspecting SIP traffic and is truly just doing Layer 2 acl's if you will.

This is the issue, from our Telcom Provider - SIP/DATA come thru the same trunk. The flow goes - ISP ------ Router ------ ASA ----- Cube ---- CUCM

Now if I make a local call outbound, all works.

If I make a long distance call outbound, 3 second delay fast busy.

ISP states that they can see the call and are receiving Invite, 100 Trying, 401 Unauthorized, ACK, Invite, 100, 183, 180, 200 on the Good Call (local outbound).

ISP states that on long distance outbound they are seeing - Invite, 100 Trying, 401 Unauthorized, ACK, Invite, Invite, Invite. The reason that they are receiving the Invites is that the detail information (sorry my SIP knowledge is on the Newbie level).

Our communicaiton is over ports 5060/5070. Do have two service policies at ASA - the default global SIP inspection and custom for port 5070 SIP Inspection. If I  disable SIP inspection rule on either no SIP calls will work.

Any idea why the information would be missing from a LD call whereas the local call has?

Captured from ISP side:

Detail Data:

---- ETH ----

   Destination Address: 00-08-25-A1-E4-EE

   Source Address: 00-09-E9-B5-00-00

   ---- 802.1Q Virtual LAN ----

      81-00 = 8100h [33024d] Type

      {011. ....}= 03h [003d] Priority

      {...0 ....}= 00h [000d] CFI


      {.... 1011}= 0Bh [011d] bits 11-8

      {1011 0111}= B7h [183d] bits 7-0

      ID = BB7h [2999d]

      08-00 = 800h [2048d] Protocol Type: Internet IP (IPv4)

---- IPv4 ----

   ---- IP header ----

      {0100 ....}= 04h [004d] Version: IP Internet Protocol

      {.... 0101}= 05h [005d] Header length: in 32 bit units - must be 5 or more

      ---- Type of Service ----

         {011. ....}= 03h [003d] Precedence: Flash

         {...0 ....}= 00h [000d] Delay: Normal

         {.... 1...}= 01h [001d] Throughput: High

         {.... .0..}= 00h [000d] Reliability: Normal

         {.... ..0.}= 00h [000d] ECN Capable Transport(ECT): No

         {.... ...0}= 00h [000d] Congestion Experienced(CE): No

      05-DA = 5DAh [1498d] Total length: in octets, including header length - must not be less than 20

      00-1E = 1Eh [030d] Identification

      {0... ....}= 00h [000d] reserved: valid

      {.0.. ....}= 00h [000d] Don't Fragment (DF bit): May Fragment

      {..0. ....}= 00h [000d] More Fragments (MF bit)

      Fragment offset:

      {...0 0000}= 00h [000d] bits 12-8

      {0000 0000}= 00h [000d] bits 7-0

      Fragment offset = 00h [000d]: in 64 bits units

      {1111 1000}= F8h [248d] Time to live: Hops

      {0001 0001}= 11h [017d] protocol: UDP (User Datagram)

      6E-91 = 6E91h [28305d] Header checksum: checksum is correct

      source ip address: 64.x.x.x.x

      destination ip address: 4.x.x.x

   ---- IP datagram ----

---- UDP ----

   ---- UDP header ----

      F3-6E = F36Eh [62318d] source port

      13-CE = 13CEh [5070d] destination port

      05-C6 = 5C6h [1478d] length: octets include header (not less than 8)

      07-E4 = 7E4h [2020d] checksum: checksum is correct

   ---- UDP datagram ----

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