11

In routers you normally have two separate planes, often called "control plane" and "forwarding plane". The control plane is the "brain" of the router and handles things as management of the device and routing protocols among other things. It is sometimes called a "routing engine" or "supervisor" by vendors. The forwarding plane is responsible for the ...


6

IP forwarding tables are commonly stored in an m-trie, which is a 256-way trie. If the forwarding table was implemented as a 256-way m-trie, then 128.92.128.0/17 would contain the mtrie entries for 128.92.128.0/18... although these two routes could easily go to different IPv4 next-hops, since IP routing works on the principle of longest-prefix-match wins. ...


6

Calling a switch mac address table a Forwarding Information Base is incorrect. The correct term, according to the original 8021.D document is Filtering Database, although this term is not commonly used. This database is more often referred as a Mac Address Table -not to be confused with the ARP table- this is the term you will find in many switch interface ...


5

Routing protocols, in general, are used to populate the routing tables and not to forward packets. Between two AS it is generally BGP that is used to exchange routes, and within an AS, it can be OSPF, but could also be IS-IS, EIGRP or any routing protocol. A given router can use several routing protocols at the same time. Lets say a router is configured ...


4

Both routes would be installed into the active routing table and the more specific route would win if it was relevant to the packet being routed. 128.92.128.0/18 will be installed but so will 128.92.128.0/17 as the /18 doesn't cover all of the /17. If you had static routes configured like this... 128.92.128.0/18 VIA x.x.x.x 128.92.128.0/17 VIA z.z.z.z ...


4

I thought that first of all the network doing the STP algorithm, to find the best tree to send packets between LANs. Spanning Tree is not a routing protocol, but a protocol to avoid loops in a network. Therefore, whenever the network topology changes (links comes up/goes down), Spanning Tree is gathering information about the network and the link between ...


4

Yes, the openflow protocol supports the creation of flows with multiple actions, and each action can be to send a frame/packet out a certain port. However, whether or not your openflow switch supports this is a different matter. E.g. this Cisco doc states that only "output to a single port" is supported by version 1.1.5 of their Openflow agent on Nexus ...


3

You are mixing different concepts, so the first step is to make clear each one: STP: A device in a LAN can communicate to another device on the same LAN directly. When a device is in a LAN it uses the MAC address to identify the other devices. Being in a LAN means that the device periodically sends unicast (peer to peer) frames and broadcast (peer to ...


3

(copying from the comments as it was confirmed to be the solution) If 10.10.2.4 can ping 10.10.1.2 successfully then L2 and L3 connectivity appear to be ok and so 10.10.1.2 should also be able to ping 10.10.2.4. If not, then the most likely explanation is that a host-based firewall on 10.10.2.4 is dropping the pings.


3

When A send a frame to C, the switch learn the mac address of A and flood the frame to all ports except 1 (since it received the frame on this port). Such, B and C both receive the frame. Since the frame contains C mac address as destination address, B knows it is not the intended recipient and drop the frame. C process the frame and reply. The switch ...


3

Office1 and R1 aren't on the same network -- even the network mask is different. R1 and R2 aren't on the same network neither: R1 is on the 10.0.6.180/30 where R2 is on 10.0.6.184/30, so that point-to-point link is never going to work. Additionally, once you set up correct IP addresses for all interfaces, we'd need to know the routing tables from all ...


3

This may seem a little counter-intuitive, but you need to change the "Translations" IP address to 192.168.1.2 and remove the IP address from the "Dest Address" field. What the configuration is actually telling the device is that when you receive traffic with destination address/port on this interface, translate it to the translation address/port. The ...


3

Packet forwarding is forwarding based on the network-layer address of a packet. Usually this is refered to as "routing". Network address translation (NAT or rather NAPT) is used when connecting a network using private IPv4 addresses to a network using public IPv4 addresses, or when the addressing schemes on both sides don't mix for other reasons. Most often,...


3

Basically packet is forwarded towards destination based on routing decision made by layer3 device routing table is created in layer3 routing decisions is based on perimeter like Administrative value (AD) metric **NATing ** NATing translation private ip address to public ip address . This kind of transportation is used for security purposes to hide our ...


2

The sonicwall can point to one of your own internal DNS servers (running on another device in your network), but it doesn't include a DNS server itself. You can set your server up to do DNS and point the sonicwall at it, then all DHCP clients will use that server for name lookups. If you have multiple websites and multiple employee workstations, it's worth ...


2

Routes with different prefix lengths are really different routes so they end up in the routing table. The route with the longest prefix will be used for the routing decision. Metrics are used by a routing protocol to determine the best route to be offered as a candidate to the routing table. Administrative distance will be used by the routing table as the ...


2

Basically, the control plane is for data destined to the router itself (e.g. routing protocol updates), while the forwarding (data) plane controls what goes through the router. The forwarding plane can make decisions based on what is learned in the control plane, but the control plane itself doesn't make the forwarding decisions. It sounds like you are sort ...


2

If you are referring to the routing of an IPv6 packet, it is really only the destination address which plays a part in that. The Hop Count field is first inspected to see if the packet should be dropped. If the packet is not dropped, the field is decremented and the packet is forwarded, or dropped, based on the destination address. The only extension ...


2

About Route Cost and Distance Vectors As xpac said, different routing protocols use different methods to find the best route to a specific network. The idea of a routing protocol is that it allows routers to learn from other routers what networks are attached to which router, instead of you typing everything into every router by hand. A route is basically ...


2

I found that using Group Tables that is supported in OpenFlow since version 1.1 of the standard, it is possible to replicate and process a packet through multiple buckets of actions. If a group table entry is from type "ALL", then all action buckets in the group are executed which can be used to forward a packet to multiple outgoing ports. A number of ...


2

When the gateway address for a route points to one of the host's interfaces it means "I'm the gateway, I'm able to transmit to this destination directly."


2

Dijkstra's Algorithm doesn't define what the weight should be. The weight value lets you decide which links are preferred. If, as you say, all the links have the same bandwidth, then perhaps you don't have a preference. All weights should be the same.


2

R2's configuration doesn't need to change, but client 2 needs to know the address of client 1, or it needs to resolve the DNS name for it. It would be the same problem if there were no routers between client 1 and client 2.


2

Depending on your actual goal, there are several possibilities. Load balancing your flows 'at will' requires them to be split across different VLANs or very delicate fine tuning. VLANs with spanning tree Using MSTP with multiple instances or RPVST+, you can arrange/configure your VLANs onto both links and then connect the switches redundantly but with ...


2

I want to know that it is a must for ISP routers to cache all these million IPv4 entries? No. However, ISP's & CDN's wanting to run within a DFZ (Default Free Zone) will usually hold all of these prefixes. Do any differences exist between tier 1 or tier 2 ISPs when answering this question? The only difference you may see here is the source of the ...


2

For the purposes of this post, I will use the following definitions of the tiers. A tier 1 ISP is one that relies purely on peering and does not use transit. A tier 2 network (may or may not be an ISP) is one that uses a mixture of peering and transit. A tier 3 network (may or may not be an ISP) is one that relies purely on transit. (many definitions of "...


1

They definitely don't keep the same informations. Routing table is a L3 table which states for X.X.X.X/Y IP destination, go through z.z.z.z router. Forwarding table is a L2 table which states for communicating with z.z.z.z router, send packets to Mac Address aa:bb:cc:dd:ee:ff. In your local network, you use the forwarding table to get the other hosts mac ...


1

Apparently, your router's WAN side is part of a subnet. From its own public IP it has to use the default gateway (upstream router) for destination addresses outside that subnet. This gateway needs to be located within the subnet. This is perfectly normal. If you need to understand subnets, prefixes and such check out this question.


1

1) Any host requires a routing table. At minimum it's the default route 0.0.0.0/0 pointing to the default gateway. Without a default gateway the host wouldn't know where to send non-local packets. 2) Routers also forward packets based on their routing table. Routing table entries contain (at least) the destination network address with mask and the next hop. ...


1

I'll briefly answer the question. The RIB (routing information base) contains all of the knowledge the router has obtained about how to reach destination networks. For example, it may have two different paths to reach the same network, both stored in the FIB. Or it might have learned the path the same network via two different routing protocols. Again, ...


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