I want to add an IPv4 multicast route say 225.0.0.9 to the multicast routing table of Linux. Is it possible to do so using any C program code? Any existing application this performs this task would also work.
I've found numerous posts that add a multicast route to the unicast routing table using command route add 225.0.0.9 dev eth0 but this is not what I really want.
Please provide any directions or clarifications for the same.
The hard way to manipulate route and mroute table is by using the rtnetlink API. This is not something I recommend if you only need this single function, since that API can be tricky if you are inexperienced with playing with pointers and structs wrapped into each-other.
The easier way is to just fork out a helper process and execute ip commands, since ip implements all of the features you need via command-line.
Related
I used to see Cisco's approach when configure BGP:
router bgp 64511
network 101.10.0.0 mask 255.255.255.0
...
ip route 101.10.0.0 255.255.255.0 null0
that is, I need to add the network to routing table so I can advertise it.
Now I need to configure FRR routing suite which mostly mimics the Cisco's config language, and I really doubt if I should (or shouldn't ) add the line route ... null0.
The idea behind adding the line is that Cisco used to require that, idea behind not adding is that Linux (which is underline layer) won't be happy to see extra subnet in its routing table.
Please advice!
(Sorry if I misplace the question, not aware where network questions should go to).
Any routing protocol is working this way: it is sharing routes from it's own routing table to the next hop. You don't need to add route to the Null0 (route to nowhere) if you already have it in your routing table (got it from other hop or it is configured for another interface).
Route to the Null at the example used to add it to the local routing table of the device.
BTW using route to the Null0 is good way if you want to summarize you networks and advertise only this one big network instead of lot of small networks. Routing still be working (because small network have highter priority) and if you will get packets to the host to non existing network it will just drop it by rule => Null0.
I want to test my multicast routing algorithm implemented in the SDN controller. I'm generating my test network topology using Mininet emulator.
According to my knowledge, there's no feature in Mininet which allows me to send packets from one sender to multiple destination (multicast). I've already tried to find the answer to that question in network, but i cannot find any.
So, how can i do that?
You could use Group Table that's supported by OpenFlow v1.3. Then you can do multicast by having a group table with multiple buckets and each bucket outputs to a designed port.
Update: Ryu igmp controller written in Python: https://github.com/osrg/ryu/blob/master/ryu/app/simple_switch_igmp.py
Currently, I'm writing an application on top of Ryu, the Open-source OpenFlow Controller.
To create an OF-Config connection (or OVSDB connection), I think I have to get the IP address of each switch connected to the Ryu controller. However, I cannot find the API that converts the Datapath object or datapath id to the IP address of the switch.
So, if there is such an API, I want to know about it. If not, I'm looking forward to receiving some comments about the way to make the connections without the IP addresses.
#set_ev_cls(event.EventSwitchEnter)
def switch_features_handler(self, ev):
address = ev.switch.dp.address
dpid = ev.switch.dp.id
"address" is a tuple of (ip_address, port) and "dpid" is the datapath id.
Byungjoon are you using mininet?
If you are, all the switches are instantiated with the localhost ip address (This is mininet's default behavior). The controller distinguishes between switches using the tcp port.
As far as I know, you only need to know the dpid of the switch in order to send OF messages. This is what the sample l2-learning switch is doing: https://github.com/osrg/ryu/blob/master/ryu/app/simple_switch_13.py
I am also try to communicate with the switches using Ryu controller. I am using the above sample as my basic code and adding on top of it. It is not done yet (so you might see some bugs) but it's good starting point. Here is the link: https://github.com/Ehsan70/RyuApps/blob/master/l2.py
for latest version of ryu, you should use following code.
#set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
def _switch_features_handler(self, ev):
print(ev.msg.datapath.address)
I have a linux system with two eth cards. eth0 and eth1. I am creating a client that sends
to endpoint 1.2.3.4.
I send my webservice with soap_call_ functions. How can I select eth1 instead of eth0?
the code is like that
soap_call_ns__add(&soap, server, "", a, b, &result);
How can I set inside the &soap variable the eth0 or the eth1?
(gsoap does not have a bind for clients... like soap_bind)
You want outgoing packages from your host to take a specific route (in this case a specific NIC)? If that's the case, then you have to adjust kernels routing tables.
Shorewall has excellent documentation on that kind of setup. You'll find there info about how to direct certain traffic through a particular network interface.
for gsoap we need to manually bind(2) before connect(3) in tcp_connect
I'm working with a cluster of about 40 nodes running Debian 4. Each node runs a daemon which sits and listens on a multicast IP.
I wrote some client software to send out a multicast over the LAN with a client computer on the same switch as the cluster, so that each node in the cluster would receive the packet and respond.
It works great, except when I run the client software on a computer that has both LAN and WAN interfaces. If there is a WAN interface, the multicast doesn't work. So obviously, I figure the multicast is incorrectly going over the WAN interface (eth0), rather than the LAN (eth1.) So, I use the SO_BINDTODEVICE socket option to force the multicast socket to use eth1, and all is well.
But I thought that the kernel's routing table should determine that the LAN (eth1) is obviously a lower cost destination for the multicast. Is there some reason I have to explicitly force the socket to use eth1? And, is there some way (perhaps an ioctl call) that I can have the application automatically determine if a particular interface is a LAN or WAN?
If you don't explicitly bind to an
interface, I believe Linux uses the
interface for the default unicast
route for multicast sending.
Linux needs a multicast route, if none exists you will get a EHOSTUNREACH or ENETUNREACH error. The LCM project documents this possible problem. The routing will be overridden if you use the socket option IP_MULTICAST_IF or IPV6_MULTICAST_IF. You are supposed be able to specify the interface via scope-id field in IPv6 addresses but not all platforms properly support it. As dameiss points out, Stevens' Unix Network Programming book covers these details, you can browse most of the chapter on multicast via Google Books for free.
If you don't explicitly bind to an interface, I believe Linux uses the interface for the default unicast route for multicast sending. So my guess is that your default route is via the WAN interface.
Richard Stevens' "Unix Network Programming, Vol. 1", chapter 17 (at least in the 3rd edition), has some good information and examples of how to enumerate the network interfaces.