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    Tracing Control Packets

    Requirements

    This example uses the following hardware and software components:

    • An operational MX chassis
    • Junos OS Mobility package

    Tracing Control Packets

    This section shows how to trace Gi to Gn control packets.

    To efficiently monitor the data path, perform the following checks:

    • Verify that the Gn interface (IFL) is receiving packets.
    user@host> show jnh if statistics
            IFL Name            Index     In(Packets/Bytes)    Out(Packets/Bytes)
    ---------------- ---------------- --------------------- ---------------------
          

    Verify that the packets are hitting the filter.

    user@host>show filter
    Program Filters:
    ---------------
       Index     Dir     Cnt    Text     Bss  Name
    --------  ------  ------  ------  ------  --------
    
    Term Filters:
    ------------
       Index    Semantic   Name
    --------  ---------- ------
           1  Classic    __default_bpdu_filter__
       17000  Classic    __default_arp_policer__
       57008  Classic    __cfm_filter_shared_lc__
       65280  Classic    __auto_policer_template__
       65281  Classic    __auto_policer_template_1__
       65282  Classic    __auto_policer_template_2__
       65283  Classic    __auto_policer_template_3__
       65284  Classic    __auto_policer_template_4__
       65285  Classic    __auto_policer_template_5__
       65286  Classic    __auto_policer_template_6__
       65287  Classic    __auto_policer_template_7__
       65288  Classic    __auto_policer_template_8__
    46137345  Classic    HOSTBOUND_IPv4_FILTER
    46137346  Classic    HOSTBOUND_IPv6_FILTER
    67108864  Classic    __mobile_gw_impl_filter__      <<<<<<<<<<

    Display counters for index 67108864.

    user@host> show filter index 67108864 counters
    Filter Counters/Policers:
       Index               Packets                 Bytes  Name
    --------  --------------------  --------------------  --------
    67108864                     5                  1025  __gtpc_pkt_count
    67108864                     5                   500  __gtpu_pkt_count
    67108864                     0                     0  __mgw_ip_frags_count
    67108864                     0                     0  __sp-1-0_GTP_pkt_count
    67108864                     0                     0  __sp-1-0_LIBAAA_pkt_count
    67108864                     0                     0  __sp-1-0_LIBCHRG_pkt_count

    Check the group TEID route table.

    user@host> show route gtp-c
    1/8                                              Service   653 
    1.0/13 Service 653
    1.0.0.0.0/40 Service 653

    Note: The 1 at the beginning here is the GTP-C route-type. If the teid=0 route (1.0.0.0.0/40) is missing, verify that rmpsd on the Routing Engine installed those routes or verify that it is running.

    user@host> show filter nexthops
                               Name Protocol         Type Option Refcount  NH ID
    ------------------------------- -------- ------------ ------ --------  -----
        ms-1/0/0.16000:mgw:SPFE-AAA     IPv4      service   0x01        0    650
       ms-1/0/0.16000:mgw:SPFE-CHRG     IPv4      service   0x01        0    648
        ms-1/0/0.16000:mgw:SPFE-SMA    GTP-U      service   0x01        0    653
       ms-1/0/0.16000:mgw:SPFE-UPIC    GTP-U      service   0x01        0    656
    
    
     

    Display details on service 653.

    user@host> show nhdb id 653 extensive
      ID      Type      Interface    Next Hop Addr    Protocol       Encap     MTU       Flags  PFE internal Flags
    -----  --------  -------------  ---------------  ----------  ------------  ----  ----------  --------------------
      653   Service  -              -                     GTP-U             -     0  0x00000000 0x00000000
    Target NH: 654
    PFE#0, Target Addr = 0x1fcbc1
           SvcDesc   = 0x1fcbff
    PFE#1, Target Addr = 0x1fcbfe
           SvcDesc   = 0x1fcbfd

    Verify the nexthop target 654.

    user@host> show nhdb id 654 extensive
       ID    Type      Interface    Next Hop Addr    Protocol       Encap     MTU       Flags  PFE internal Flags
     

    Check whether the NH-id point to the correct ms-ifl.

    user@host> show mobile-edge halp ucode-nhs
    Nexthop ID                         Purpose
    ------------------------------------------------
    
    4194306                            GTPv0 parsing ucode
    4194307                            GTP-C v1/v2 parsing ucode
    4194308                            GTP-U swap ports ucode
    4194309                            DHCP parsing ucode
    4194310                            GTP-C table NH
    4194311                            GTP-U table NH

    Check to see whether packets are discarded or punted the to host.

    user@host> show jnh 0 exceptions
    Ucode Internal ---------------------- mcast stack overflow             
    ...
     
    Packet Exceptions
    ----------------------
    bad ipv4 hdr checksum              DISC( 2)
    non-IPv4 layer3 tunnel             DISC( 4)           0          0
    GRE unsupported flags              DISC( 5)           0          0
    tunnel pkt too short               DISC( 6)           0          0
    bad IPv6 options pkt               DISC( 9)           0          0
    bad IP hdr                         DISC(11)           0          0
    bad IP pkt len                     DISC(12)           0          0
    L4 len too short                   DISC(13)           0          0
    invalid TCP fragment               DISC(14)           0          0
    mtu exceeded                       DISC(21)           0          0
    frag needed but DF set             DISC(22)           0          0
    ttl expired                        PUNT( 1)           0          0
    IP options                         PUNT( 2)           0          0
    control pkt punt via ucode         PUNT( 4)           0          0
    frame format error                 DISC( 0)
    tunnel hdr needs reassembly        PUNT( 8)           0          0
    GRE key mismatch                   DISC(76)           0          0
    my-mac check failed                DISC(28)
    frame relay type unsupported       DISC(38)           0          0
    IGMP snooping control packet       PUNT(12)           0          0
    bad CLNP hdr                       DISC(43)           0          0
    bad CLNP hdr checksum              DISC(44)           0          0
    incorrect length in GTP header     DISC(45)           0          0
    GTP header errors                  DISC(46)           0          0
    Bearer using different IP address  DISC(47)           0          0
    expecting sequence number          DISC(48)           0          0
    sequence number isnt correct       DISC(49)           0          0
    SR is marked for traffic discard   DISC(50)           0          0
    
    Firewall
    ----------------------
    mac firewall                       DISC(78)
    firewall discard                   DISC(67)           0          0
    tcam miss                          DISC(16)           0          0
    firewall reject                    PUNT(36)           0          0
    firewall send to host              PUNT(53)           0          0
    
    Routing
    ----------------------
    discard route                      DISC(66)           0          0
    hold route                         DISC(70)           0          0
    mcast rpf mismatch                 DISC( 8)           0          0
    resolve route                      PUNT(33)           0          0
    control pkt punt via nh            PUNT(34)           0          0
    host route                         PUNT(32)        2313      92940
    ICMP redirect                      PUNT( 3)           0          0
    mcast host copy                    PUNT( 6)           0          0
    reject route                       PUNT(40)           0          0
    
    Misc
    ----------------------
    debug                              DISC(65)           0          0
    services pkt internal test         PUNT(38)           0          0
    directed bcast                     DISC(89)           0          0
    virtual-chassis pkt(hi)            PUNT(54)           0          0
    virtual-chassis pkt(lo)            PUNT(55)           0          0
    virtual-chassis error              DISC(42)           0          0
    ME-subcriber policing out of spec packet dropsDISC(52)           0          0

    To display non-zero counters, enter:

    host@user> show jnh 0 exceptions terse
    Reason                             Type         Packets      Bytes 
    ================================================================== Routing
    ----------------------
    host route PUNT(32) 2393 96140

    Another example is: a v2 call comes in with QCI 5 and gets mapped to FC af5. On that queue, you can see the PPS for the Gn-facing interface and the Gi-facing interface

    user@host> show interfaces queue ge-1/2/5 forwarding-class af5

    Where 1/2/5 is the Gn-facing interface. Then enter:

    user@host> show interfaces queue ge-1/2/1 forwarding-class af5

    Where 1/2/1 is the Gi-facing interface.

    Configuration

    Tracing Packets

    Step-by-Step Procedure

    Results

    This example illustrated the steps you can take to trace control packets.

    Published: 2011-11-16