An IP packet of size 1500 bytes passes through two network segments before it reaches its destination. The header size of this packet is 20 bytes. The maximum size of an IP packet in the first intermediate network (its MTU) is 1024 bytes, and that in the second network is 576 bytes.Explain how the IP packet described above would be fragmented into smaller parts in a router, paying particular attention to the flag bits and to the fragment offset field in the header.
- Fragmentation and reassembly needs to break a data-gram into an almost random number of pieces that later can reassembled.
- It uses the identification field to ensure that fragments of different datagrams are not mixed.
- IP packet of 1500 bytes comprises 1480 bytes of data and a 20-byte header.
- In the first intermediate network, the packet size of 1024 bytes allows for 1000 bytes of data plus a 20-byte IP
header.[code]
I am trying to use my WRT120n as access device for an IP Centrex service using SIP protocol. My SIP phone is located right behind the router.My problem is sometimes the router is dropping incoming calls because signalling packets are fragmented at IP level. So I cannot receive those calls.Is there a way to enable the router to accept these packets?
I have a synology 1511+ nas. My network transfer speeds are very slow, < 1meg a sec in some cases. It's next to unbearable.Anyway was reading about this thing that said to ping it using the -f settings and here's the result.
Pinging 192.168.1.139 with 2000 bytes of data: Packet needs to be fragmented but DF set. Packet needs to be fragmented but DF set. Packet needs to be fragmented but DF set. [Code]...
The website said to adjust the MTU settings in order to get rid of this message but I don't know what to change.
i got trouble for this ipv4 & ipv6 fragment trafic prob/attack.how do i prevent it from comming in to my network? is it way to prevent it in cisco router part?
I'm having some issues calculating CIDR notation, I'm just not able to get a solid grasp on it. [URL] but I'm not seeing how to calculate it. how to calculate it?
I want to calculate Subnet Mask for 3 Router Each one in separate building the First building need 60 host and the second building 25 host and the last one 25 host .
Knowing that the company currently reserved public class C network address 210.2.1.0/24 for internal address and subnet 210.15.10.0/30 for the connection to the Internet router.
Researching different ways to find the Broadcast address I took the binary IP address and replaced all numbers with 1's for the host bits identified in the subnet mask and came up with:
I am not sure what is meant by the network address and all my research has come up with either MAC addresses (obviously wrong) or CIDR notation...How do I calculate the network address?
Part 3 - List of valid IP's
Using the same address 172.16.10.22/28 I did the following:
28 is closest to 32 (block wise) so 32 - 28 = 4... 2 ^ 4 = 16 (block size)
IP address listing: 172.16.0.0 172.16.16.0 172.16.32.0 172.16.48.0 172.16.64.0 and so on...
The IP address in question is 172.16.10.22 and falls in the 172.16.0.0 - 172.16.15.0 block...
I need to know exactly how much bandwidth my service provider is giving me throught an MPLS network. My providers tells me that I am capped at 5 mbps with 4 T1 circuits but I believe that I am receiving 6 mbps.
I have a remote site in Dallas with a 2850 and another site as a head end in Michiagan which is a 7206 router.
What exactly can I do during non-business to test to see what the bandwidth is between the 2 locations? Is there some type of command that I can run on the router to test this?
I want to measure the the ospf convergence time on the given network topology (assume 5 nodes - partial mesh topology).I am using quagga software as routing software on linux box. Quagga is runnign fine and network is converged, able to see all the routes.. Quagga software is logging all the osfp information includign packets,state machines,etc.I am going to disconnect a link between node a to node b. and i want to measure the convergence time of the network.What is the network convergence time?My answer is, The time taken to reflect the topology change (link down/up, network condition change) to all the routers on the topology.Some routers(close by routers to the topology change) will get converged fast, and some routers(far away from the topology change) will have the higher convergence time. we have to take the highest convergence time of the router on the topology and we can says thats the ospf network convergence time.
How can know the Broadcast address before subnetting? I know how to calculate the broadcast address , but don't understand 'Broadcast address before subnetting'?
I've no experience in VoIP and been ditched with looking at an IP trunking problem on our network.The users where getting dead lines or silent calls, but it seems after re-seating IP trunking card here and there around the network a few times, all is settled to normal. Unfortunately it's a third party that look after the majority of the telephony, and as they can't figure out why this happens they often say it must be a problem with the data WAN it traverses.So I started trying to figure something out, I have IPSLA monitoring setup in Solarwinds on most of the routers and all looks well from that aspect; MOS is 4.34 and Jitter is only 1ms at worst. I've taken a wireshark packet capture of the IP trunk by mirroring the port on the switch at a main site where I've been told a lot of calls are routed through. Inside wireshark I used the 'telephony> voip calls' tool and decoded all the calls. The output is showing most calls have 'Out of Seq' and 'Wrong Timestamp' at around 25-50%. Although these calls seem fine otherwise, and I took this capture whilst the fault was not occurring. I know I need to capture next time when the fault is occurring, but this is what I have for now.How can i fix this or even start to troubleshoot further?
p.s- each site has two routers running GLBP to the WAN, over two ISP locations. I read something about having consistent routing to avoid packets arriving out of sequence, but haven't found anything yet to say this is how I can/should do that.
I use a wireless adapter to connect to our home network but its stopped receiving packets but is sending them. It has worked fine for ages now it just randomly stopped. The network works with everything else (laptops, Xbox and iPods) but my pc wont receive anything. Also our home connection has no password as we live in the middle of nowhere.
I am having a really hard time with a computer that has a wireless connection. Specifically the internet keeps going out. The computer info is that of the affected computer and not the host computer to which the router and modem are connected.
I can connect to it fine and access everything behind the VPN. I have a Windows 7 machine 32 bits. He can connect to the VPN just fine but not access anything behind it, he is running Windows 7 64-bits. This is not a new setup, the VPN has been working before. If I debug ISAKMP and IPSEC in the ASA I see nothing out of the ordinary. The only thing I see is that the VPN client on his machine is showing that the counter for discarded packets is increasing. This is Ciscos explanation to discarded packets. "Packets discarded—The total number of data packets that the VPN Client rejected because they did not come from the secure VPN device gateway." So it seems that the client does not believe that the packets are from the ASA. I have no idea why that would be and what could have changed that made a functioning VPN turn into a non functioning one. He can not remember doing any major installs or something like that which could mess with the client. We uninstalled the version he was using and installed a slightly newer version but it made no difference.
While troubleshooting high cpu due to interrupts on platforms like 6500 or 7600 we can capture the packets getting punted to the CPU using netdr or on 4500 I think we can even use monitor session. But is there a way where we can capture/sniff packets reaching the CPU on a 7206vxr with NPE-G2?
I have a NAT setup. Some of my udp packets are dropping. How to find more about the NAT to find whether it missed anything or not. the router is 3945e. [code]
I have a weird issue with a QOS policy that I have implemented. Details are below.
This is basically the policy I have created. It is running on a Cisco 877 router (running Advance IP Services 12.4). The internet connection is an Internode ADSL service.
class-map match-any VOIP match access-group name VOICE-OUT ! !
I have ACE10 Module in my switch core 6509, my context "Proxy" was criated for balance connections to Forefront TMG Servers, this balance needs original client IP Address connections end to end in the solution.
My problem is: The clients are complaining of slowness connection to the internet, i captured the traffic in the ace capture feature and i see some RST packets and severals checksum error packets in pcap file.
The topology is:
Client -> ACE VIP VLAN 81 -> RSERVERS VLAN 80
Vlan 80 is in L2 mode(no interface vlan in the switch core 6509, route occurs through the ace appliance). The IP address 10.96.200.6 is the gw for rservers. [Code]...
Ive just downloaded wireshark just to mess around and ive noticed that even when ive got nothing open its still capturing packets. It gives me a choice of interfaces i want to choose to monitor and i would of thought it be "Realtek PCIe Family Controller" as this is normally the default one (im using wireless) but its saying no packets are being captured from this interface its the "Microsoft" Interface thats capturing the packets. Ive attached a screenshot, i know this isnt nothing bad but was just wondering 1) why isnt my Realtek PCIe interface capturing anything?
One Day the internet is fine the next day The Internet Stopped working. The problem is my pc is sending packets but not receiving any i though it was a bug or something so i restarted my pc after i restarted my pc the internet was working fine until a couple of minutes passed it stopped receiving packets again.i tried resetting the modem but nothing worked.I tried winsock fix or resetting TCP/IP and stuff but nothing workscause its starting to frustrate me.
Our computer is sending but not receiving packets. We've tried 3 different wi-fi adapters, and that wasn't the problem. We have no idea what's wrong? It won't pick up any wireless signals by the way, and it works fine while connected via Ethernet.
I have a home network that does not connect to the internet, but which I use to play games on, or did before this issue happened by.For years my PC's and friends ones had been able to connect into the network with little or no problems, but a few months ago my tower PC just stopped picking anybody or anything up on the network and I have tried tons of different resolutions to solve this.Anyway, the other day I bought a new HD and installed XP SP3 again on it, and for about fifteen minutes I could connect to my Vista Laptop and share files and play games, then it stopped.Next day the same again and off and on till now when its been down for the last week.I have also now bought a new network card - no difference - and disabled the on board network card through the BIOS - no difference.I have done a Winsock repair, replaced automatic IP addresses with manual ones, and countless other remedies which have not solved diddly.
I have connected the computer to the internet a multitude of ways, and no matter how i do it, it always can not receive packets. It is sending packets though.I have tried connecting it directly to the modem, with different wires, through a router, through a network card... I'm pretty much at a loss, im not an expert by any means but im not computer illiterate either. Chances are this is a simple fix... My other computer (the one im on) works fine with both cords, connected directly, and through the router to the modem.
Basically a while ago last year some time in December my desktop got turned on one day and the internet wasn't working. I tried using my wireless to connect but even that was stuck on "acquiring network address". Ive played around with it abit since then and now my etherent cord shows up as connected but when I go into properties it says no packets getting sent / received. In device manager all my network adapters are cool and dont have any "!" next to them.Ive also tried the cord in my laptop and it works cool.
I am capturing at 2 different locations and I need to find packets that are getting dropped between the 2.
I have done all the merging and everything needed for this in wireshark but because the mac address changes 1/2 way to me all the packets are coming up as lost
is there anyway to remove the MAC address from the captures or as a field it looks at?
