Consider the network shown above. Suppose all ASs are running OSPF for their intra-AS routing protocol, with the cost of each link equal to 1. Suppose eBGP and iBGP are used for the inter-AS routing protocol. Initially suppose there is no physical link between AS2 and AS4.
Routers(1a,1b,1c,1d,2a,2b,2c,3a,3b,3c,4a,4b,4c) learns about prefix x from which routing protocol: OSPF, RIP, eBGP or iBGP?
I'm so confused on BGP, I think the answers should be either eBGP or iBGP. Can anyone help me with this and explain why?
(I think 1c and 3c should be eBGP, and 3a and 1d should be iBGP. Not sure about others)
First of all, since all the ASs run OSPF why you believe it's either eBGP or iBGP and not OSFP? What point exactly confuses you?
The border routers 3c, 1c, 2a will learn it through eBGP, because they will learn the prefix from a router outside their AS.
The other routers will learn it through the intra-domain routing protocol, which is OSPF, because they will learn the prefix from a router that belongs to the same AS.
Think how the prefix is propagated to by each router to their next-hop neighbours to understand from which protocol the prefix will be learned at each router.
The prefix will be propagated as follows:
4a -> 4b -> 4c --> 3c -> 3b -> 3a --> 1c -> 1a -> 1d and 1b --> 2a ->2b and 2c
I think the solution is simple and because the question is 9 days old I hope you took the time to study routing if it was a homework. Generally, it would be better to explain and discuss which points you don't understand rather than go directly for the solution, it will help you more in the long term.
I could not comment on the Vasilis's answer since i have not enough reputation points...
There is nothing said that the BGP routes are redistributed into OSPF, thus route to X can't be learned via OSPF in ASs 1,2,3. OSPF simply does not have this route in its routing table.
We can only assume that X is present int OSPF in AS4 and is redistributed into BGP, thus, all routers within AS will learn it via OSPF (and iBGP is we assume OSPF is redistributed into BGP in AS4).
Next, the route propagates to AS3, 3c will learn the route via eBGP, other routers will learn it via iBGP. Same with other ASs because there isn't link between AS2 and AS4 only "upstream" routers (closer to AS4) in each AS will learn it via eBGP, it is a very important point in this task.
If there was link between AS2 and AS4, each AS border router (the one that is connected to another AS) whould learn it via BOTH eBGP and iBGP but would prefer eBGP.
There are actually many missing points in this task such as redistribution of route X in AS4.
Related
Assume we are working with TCP/IP connection.
According to https://wiki.linuxfoundation.org/networking/kernel_flow tc works on Layer 2. However, everywhere else in the internet term "packet" is used to describe the units of data that tc works with.
What does tc actually work with - Packets or Frames?
Traffic control (also called Quality of Service) can be performed at layer 2 or layer 3 or both. Remember that layers are an abstract concept, so when applied to actual hardware/software, things can get a little murky.
I want to know full form of MI2S. Through wikipedia page i find about
I2S.
I²S (Inter-IC Sound), pronounced I-squared-S, is an electrical serial bus interface standard used for connecting digital audio devices together.
So what is M stands for in MI2S.
Multiple. The protocol is the same as I2S, just more channels are supported.
Page 76
Example
Can someone tell me about the difference between GY and RO interfaces used by diameter protocol ???
As per my understanding both of this interfaces looks pretty similar and the AVP's used too.
But still i understand that there is a difference..
Ro is a 3GPP reference point that describes the connection to the OCS from another functional component. It is a general term that covers multiple connecting components such as GGSN, P-GW, WLAN, IMS AS, MBMS server, etc.
Gy is an specific instance of the Ro reference point that connects a charging component from the packet-switched domain (PS domain) i.e. PCEF within a GGSN or P-GW to the OCS
For more details
There are different 3GPP specification for each of the interfaces.
You can read the differences and see the specifications here:
http://www.ietf.org/mail-archive/web/dime/current/msg05723.html
Is it possible to (and if so, how would I), given a domain name for a particular website, look up all other domain names that redirect to that same site? I'm thinking not, though if it were possible, I'd break the problem down into two parts:
1) Get the IP address that corresponds to the original domain name (there seem to be a lot of web services that do this - although they provide me with ~4 IP addresses for the one site, any idea what that's about?)
2) Do some kind of reverse DNS lookup on those IP addresses - this yields results of the form any-in-XXXX.1e100.net (where XXXX is a 4-digit number)
So, I'm guessing this doesn't work because of redirects and things, and any-in-XXXX.1e100.net is some sort of intermediate server in between me and the domain name I'm looking up? So the task I've described above should be impossible, then, right? Can someone who knows a bit more about how DNS works confirm (or refute) this and correct any wrong assumptions I've made? Thanks!
It will only work if sites set up their reverse DNS that way. Which, I can pretty much assure you they haven't for whatever site you're considering. However, here's an example of how to do it using bind's dig utility:
Get the original address:
# dig www.google.com a
...
www.google.com. 145 IN A 74.125.239.114
www.google.com. 145 IN A 74.125.239.115
www.google.com. 145 IN A 74.125.239.113
www.google.com. 145 IN A 74.125.239.116
www.google.com. 145 IN A 74.125.239.112
Now that we have the addresses, you can issue a reverse query for it and attempt to see how it's registered:
# dig -x 74.125.239.114
...
114.239.125.74.in-addr.arpa. 656 IN PTR nuq05s01-in-f18.1e100.net.
So in this case, you can see it was at least registered. But certainly that name doesn't match the actual registered URL. So they added a reverse entry for their "service node", but not for the URL itself (ie, they didn't add a PTR record for the www.google.com record).
This will be so common you'll be hard pressed to find something where the reverse name actually matches, at least for the web. For mail servers, on the other hand, it's actually much more common. Though even they don't frequently match exactly (but at least there is almost always a PTR record in the first place`
For the love of everything, I have been at this for three hours.
OpenAL, when I move the listener, completely breaks the attenuation. I have NO idea why.
If I do not change listener settings, it works fine. But unfortunately, that is not a viable solution in a 3d game.
I have tried everything from normalizing the positions and velocities of all sound making components, to manually setting all of the attenuation settings. But changing any setting on the listener, without fail, always breaks the attenuation. I will hear sounds that are 100's of units away from me if I move the listener, as if its position has no effect.
I have even used the alGet parameters to check and see if the values are going through correctly. They are.
Each unit in the game is 1x1, so in many cases two entities will be around 100 units apart.
alListener3f(AL_POSITION, pos.x, pos.y, pos.z);
alListener3f(AL_VELOCITY, vel.x, vel.y, vel.z);
alListener(AL_ORIENTATION, system.listener.getOrientationBuffer());
alListenerf(AL_GAIN, system.listener.getMasterGain());
That is all the code in charge of changing the listener. The Master gain is 0.5f as instructed and the sounds themselves are 0.5 as well. The distance model is AL_LINEAR_DISTANCE_CLAMPED, and the reference distance is 1f, and the max distance is 2f. Still, the attenuation does not work and placement makes no difference. When in LINEAR_DISTANCE_CLAMPED mode, the distances do not work regardless. If I leave it as the default model, it will atleast work when I do not move the listener.
The orientation has been left as default (0, 0, -1f, 0, 1f, 0f)
No, my sound drivers are fine and this computer was built less than a month ago with the newest parts.
And yes, the sounds are in mono format.
Someone please help me.
I finally managed to solve my problem after some experimentation.
Setting a rolloff value that is below 1f seems to keep the sound from fading out after setting the max distance. You'll also want to make sure you're properly setting up your orientation to match your coordinate system; luckily mine was already designed to work with the default one, but be sure you do that. It's very important.
So, to make sure attenuation works correctly with reference and max angles, do the following:
Set your distance model to AL_LINEAR_DISTANCE_CLAMPED
Set your listener data to the correct values (orientation is fully set up)
Make sure your rolloff is 1f on the source
Set the reference and max distances however you want on the source
MAKE SURE the listener gain is not 0f or 1f, only in between. This does not count for sounds though, they can be 0f and 1f. 0f means "master sound is 0" and 1f means "no attenuation" for the listener.
That should be it.
Also, I've seen some talk during my studies of having to normalize your coordinates. It actually doesn't matter, as OpenAL doesn't expect you to do this (you can find this in the documentation around the bottom of page 32)
I hope I've helped someone else by clarifying all of these. Good luck on your own work, internet strangers.