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[TCP] Who can explain.

the default gw by the route table is 10.10.0.10, but tracert first hop is 10.10.0.24 Why?
C:\Program Files\Putty>netstat -rn

Route Table
===========================================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x2 ...00 0d 60 48 90 95 ...... Intel(R) PRO/100 VE Network Connection - Packet
Scheduler Miniport
===========================================================================
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0       10.10.0.10     10.10.0.117       20
        10.10.0.0    255.255.255.0      10.10.0.117     10.10.0.117       20
      10.10.0.117  255.255.255.255        127.0.0.1       127.0.0.1       20
   10.255.255.255  255.255.255.255      10.10.0.117     10.10.0.117       20
        127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1       1
        224.0.0.0        240.0.0.0      10.10.0.117     10.10.0.117       20
  255.255.255.255  255.255.255.255      10.10.0.117     10.10.0.117       1
Default Gateway:        10.10.0.10
===========================================================================
Persistent Routes:
  None

C:\Program Files\Putty>tracert 10.10.6.1

Tracing route to gw.cal.video-one.com [10.10.6.1]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  10.10.0.24
  2     1 ms     1 ms     1 ms  172.27.50.45
  3    50 ms    49 ms    49 ms  172.27.50.26
  4     *     ^C
C:\Program Files\Putty>
Report

Replies, comments and Discussions:

  • 工作学习 / 专业技术讨论 / [TCP] Who can explain.
    the default gw by the route table is 10.10.0.10, but tracert first hop is 10.10.0.24 Why?
    C:\Program Files\Putty>netstat -rn
    
    Route Table
    ===========================================================================
    Interface List
    0x1 ........................... MS TCP Loopback interface
    0x2 ...00 0d 60 48 90 95 ...... Intel(R) PRO/100 VE Network Connection - Packet
    Scheduler Miniport
    ===========================================================================
    ===========================================================================
    Active Routes:
    Network Destination        Netmask          Gateway       Interface  Metric
              0.0.0.0          0.0.0.0       10.10.0.10     10.10.0.117       20
            10.10.0.0    255.255.255.0      10.10.0.117     10.10.0.117       20
          10.10.0.117  255.255.255.255        127.0.0.1       127.0.0.1       20
       10.255.255.255  255.255.255.255      10.10.0.117     10.10.0.117       20
            127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1       1
            224.0.0.0        240.0.0.0      10.10.0.117     10.10.0.117       20
      255.255.255.255  255.255.255.255      10.10.0.117     10.10.0.117       1
    Default Gateway:        10.10.0.10
    ===========================================================================
    Persistent Routes:
      None
    
    C:\Program Files\Putty>tracert 10.10.6.1
    
    Tracing route to gw.cal.video-one.com [10.10.6.1]
    over a maximum of 30 hops:
    
      1    <1 ms    <1 ms    <1 ms  10.10.0.24
      2     1 ms     1 ms     1 ms  172.27.50.45
      3    50 ms    49 ms    49 ms  172.27.50.26
      4     *     ^C
    C:\Program Files\Putty>
    
    • should be one of the peer port on the route, i guess.
      • still not quite understand, any detail?
    • 10.10.0.0 255.255.255.0 10.10.0.117 10.10.0.117 20 ? what is the meaning of that?
      • for 10.10.0/24, go through 10.10.0.117
    • the mac address of 10.10.0.10 and 10.10.0.24 are from cisco.
    • it could be a route redirect configured on your 10.10.0.10 gateway
      • want to hear detail, thanks
        • Let's say A is 10.10.0.10 and B is 10.10.0.24.
          Your default gateway is A. So the packets are sent from your machine to A. And 10.10.6.0/24 is connected to B instead of A, then A will redirect the packets to B. In this case, it is B which will reply with a TTL expired message but not A because A, B and your machine are on the same LAN. B is the best gateway to get to your destination. That's the reason why you see B in the first hop instead of A.
          • IF router A forward packet to B, A is a hop, ttl ++. IF router A redirect route to B, routing table in host shall update - A host entry shall be seen in RT.
    • ping 10.10.0.10, ping 10.10.0.24; arp -a 10和24说不定是同一个机器?
      • different MAC, all from CISCO
    • 10.10.0.10 is logical address. 10.10.0.24 is physical address
    • there are 2 scenarios that will resault to your trace. 1. you are connecting to a layer 3 device configured with hsrp or vrrp,
      in this case 10.10.0.10 is your layer 3 (router) device's physical address and 10.10.0.24 is the logical address of the hsrp or vrrp.

      2. 10.10.0.24 is the interface address of your connected router, the routers learns the destination network 10.10.6.1 from interface 10.10.0.24.
      • coolj是真正的高手。不过我一点都不明白他在说什么。所以结论是如果你需要别人解释,就是解释了你也照样不明白。
        • Me neigher. Yet, direction is given: new terms need to study on.
        • 高手,不是拉。骗吃骗喝而已
      • By my understanding 1. the two ip address are internally in two different layer, can be both be accessed, with different priority. 2. the router use dymamic instead of statitic, at my PC. it is static route table
        Thanks, i will search keyword "hsrp" and "vrrp" to understand what u r saying.
        • virtual router redundancy protocol
      • HSRP::
        Short for Hot Standby Routing Protocol, a proprietary protocol from Cisco. HSRP is a routing protocol that provides backup to a router in the event of failure. Using HSRP, several routers are connected to the same segment of an Ethernet, FDDI or token-ring network and work together to present the appearance of a single virtual router on the LAN. The routers share the same IP and MAC addresses, therefore in the event of failure of one router, the hosts on the LAN are able to continue forwarding packets to a consistent IP and MAC address. The process of transferring the routing responsibilities from one device to another is transparent to the user.
    • Could be ICMP redirect. Does not like HSRP as it makes more sense to config the virtual IP as the default GW
      • it make sense. Don't know how to turn debug on when do ping?
        • be careful about turning on debug on a production router... could swamp the machine and someone could be fired by doing that if not done properly
          Router#debug ip packet ?
          <1-199> Access list
          <1300-2699> Access list (expanded range)
          detail Print more debugging detail

          use access list to restrict the debug scope
          • 这么严重,我还是别乱动吧,再说,公司里网络是外包的,估计口令没人知道。
            • if your company out sourced it, you may not want to touch it.... there are syslogs
              • 公司里网络一出问题就的找那个“什么都不懂”(大家都这么说)的manager, 过一会儿网络就好了。
      • 还是老猫的网络只是渊博阿。
        • Thanks. I dare not accept it. i am just a 3-leg cat.... So many DX's around that I admire....
          • haha, keqi keqi, to me, you have 6 legs.
      • actually you can see the icmp redirect packet on your host machine,
        by the way, HSRP or no matter what kind of redundant technology is transparent to the client, no difference as a single router from the view of any host machine
      • of cause the gateway will be configured with the virtual address, but when you trace, it will hit the hsrp active router's physical address.
        • easy to tell.... ping both address and use "arp -a".... the mac address of virtual IP is different....
        • Exactly... So it does not make sense that you say 10.10.0.10 is a physical address....
          • excuse my typo, i meant it vise versa. if you truly understand the technology, you should of understood what i said. okay, let me rephrase the sentence,
            just so that people like you won’t have the chance to take advantage of my typo.
            10.10.0.24 is the physical address of the hsrp or vrrp active router, 10.10.0.10 is the hsrp or vrrp's logical address.
            • can't judge by what his thought, but by his action... you may have the best intention, with wrong expression, will only leave a bad impression
              • stop whining before i bitch slap you
                • In the beginning I wanted to leave you some face by NOT replying to your msg... Not that you did not want it, what can I do? LOL
                  • you wanted to leave ME some face? you got to be _f***kin_ kidding me. what can you do? well, by stop whine like a bitch would be a good start. you'll be treated like a bitch if you continue to act like one.
                  • do you honestly believe 我需要你个sb来leave me face?hahahaha....wake up, don;t think that high of yourself, md差点儿没被你笑死
                    • Are you a man or what? if the only thing you can say is "f..k" "sh.t", you just deserve it.
                      • i'm not only a man, i am the man. i deserve a lot of things more than you can ever dream of.
      • here is more output: the two ip use different MAC, ey are all from CISCO(by checking MAC vendor code) 老猫 may be right.
        C:\Documents and Settings>ping 10.10.0.24
        
        Pinging 10.10.0.24 with 32 bytes of data:
        
        Reply from 10.10.0.24: bytes=32 time<1ms TTL=255
        
        Ping statistics for 10.10.0.24:
            Packets: Sent = 1, Received = 1, Lost = 0 (0% loss),
        Approximate round trip times in milli-seconds:
            Minimum = 0ms, Maximum = 0ms, Average = 0ms
        Control-C
        ^C
        C:\Documents and Settings>ping 10.10.0.10
        
        Pinging 10.10.0.10 with 32 bytes of data:
        
        Reply from 10.10.0.10: bytes=32 time<1ms TTL=255
        Reply from 10.10.0.10: bytes=32 time<1ms TTL=255
        
        Ping statistics for 10.10.0.10:
            Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),
        Approximate round trip times in milli-seconds:
            Minimum = 0ms, Maximum = 0ms, Average = 0ms
        Control-C
        ^C
        C:\Documents and Settings>netstat -rn
        
        Route Table
        ===========================================================================
        Interface List
        0x1 ........................... MS TCP Loopback interface
        0x2 ...00 0d 60 48 90 95 ...... Intel(R) PRO/100 VE Network Connection - Packet
        Scheduler Miniport
        0x10004 ...00 50 56 c0 00 01 ...... VMware Virtual Ethernet Adapter for VMnet1
        0x10005 ...00 50 56 c0 00 08 ...... VMware Virtual Ethernet Adapter for VMnet8
        ===========================================================================
        ===========================================================================
        Active Routes:
        Network Destination        Netmask          Gateway       Interface  Metric
                  0.0.0.0          0.0.0.0       10.10.0.10     10.10.0.117       20
                10.10.0.0    255.255.255.0      10.10.0.117     10.10.0.117       20
              10.10.0.117  255.255.255.255        127.0.0.1       127.0.0.1       20
           10.255.255.255  255.255.255.255      10.10.0.117     10.10.0.117       20
                127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1       1
            192.168.133.0    255.255.255.0    192.168.133.1   192.168.133.1       20
            192.168.133.1  255.255.255.255        127.0.0.1       127.0.0.1       20
          192.168.133.255  255.255.255.255    192.168.133.1   192.168.133.1       20
            192.168.186.0    255.255.255.0    192.168.186.1   192.168.186.1       20
            192.168.186.1  255.255.255.255        127.0.0.1       127.0.0.1       20
          192.168.186.255  255.255.255.255    192.168.186.1   192.168.186.1       20
                224.0.0.0        240.0.0.0      10.10.0.117     10.10.0.117       20
                224.0.0.0        240.0.0.0    192.168.133.1   192.168.133.1       20
                224.0.0.0        240.0.0.0    192.168.186.1   192.168.186.1       20
          255.255.255.255  255.255.255.255      10.10.0.117     10.10.0.117       1
          255.255.255.255  255.255.255.255    192.168.133.1   192.168.133.1       1
          255.255.255.255  255.255.255.255    192.168.186.1   192.168.186.1       1
        Default Gateway:        10.10.0.10
        ===========================================================================
        Persistent Routes:
          None
        
        C:\Documents and Settings>arp -a
        
        Interface: 10.10.0.117 --- 0x2
          Internet Address      Physical Address      Type
          10.10.0.1             00-10-b5-51-75-47     dynamic
          10.10.0.10            00-00-0c-07-ac-01     dynamic
          10.10.0.14            00-50-56-93-6a-75     dynamic
          10.10.0.24            00-13-1a-bc-5c-01     dynamic
          10.10.0.26            2a-01-60-00-50-02     dynamic
          10.10.0.38            2a-01-60-00-20-02     dynamic
          10.10.0.63            00-50-56-93-54-14     dynamic
          10.10.0.64            00-50-56-93-30-0c     dynamic
        
        C:\Documents and Settings>
        • and I was told, that internal network (10.10.x.x) and internet access use different line(path). I guess, 10.10.0.10 is by default set for inetnal VPN netowrk, 10.10.0.24 is for inetnet access from this location.
        • just for the record and not misleading anyone that fllowed this topic, "mikesmith(老猫)" is wrong.