New answers tagged

1

In common case balancing of two ISP is possible, but there many depends on... One TCP (and in most cases other protocols) connection absolutely impossible to balance Because of IP security on some sites one client must not change IP (at least on the go), so for flawless Internet you must lock HTTP of one client to one ISP. Is possible to overcome this ...


0

There is another variable to consider when you compare DPI with ML systems, that is the detection rates. On ML basically you are using metrics related to traffic (with no inspection on the payload) that potentially generate a lot of False positives in terms of detection, also another disadvantage is that you need to retrain your model more constantly. The ...


1

It is because you are dealing with ICMP which terminates at an interface on the Asa. In addition to your ACL, you need to permit to the interface with this command “icmp permit 100.0.10.0 255.255.255.0 outside” See cisco.com/c/en/us/td/docs/security/asa/asa-command-reference/… for full syntax. Yes it is annoying that on the ASA you need to execute this ...


2

Static routes on each router will allow both sites to reach each other's resources. Unfortunately, you can't "combine" or "load balance" your Internet connections.


4

There are multiple types of Ethernet frames. The common ones today are Ethernet-II and 802.3 ethernet. They both start the same but diverge when they get to the ethertype/length field. From Wikipedia "Ethernet frame" The "Ethertype or length" field is how you tell whether it is EthernetII or 802.3. If the field is less than 1500 then it means that the ...


3

An EtherType/Length value up to 1500 (0x05dc) indicates the frame's payload length. The values 1501-1535 (0x05dd-0x05ff) are undefined, real Ethertype values start at 1536 (0x600). The receiving switch is probably ignoring the rest of the frame and since the supposed FCS doesn't match, it drops the error frame. You'll need to use a larger value and take ...


0

If we consider switches in Main Building as Core switches, Distribution and Access Switches have resided in each building. As your topology shows, you have redundancy in your core layer, but you don't have it in the distribution layer (except building A). So if you want to have a stable network with a minimum level of redundancy you need to add at least 3 ...


4

Symmetric routing - packet takes one path towards for example google server and turn back on using the same path. Asymmetric - packet takes one path towards for example google server and return back using different path.


3

IEEE PoE (Power over MDI) is the only standard for running power over a network cable, consisting of the original PoE 802.3af (12.95 W), the improved "PoE+" 802.3at (25.5 W) and the latest "4PPoE" 802.3bt (71 W). There is a large number of proprietary variants out there as well. Most of them are not interoperable and it's possible to damage the hardware ...


2

Underlay network is a physical infrastructure that is responsible to deliver packets for you. On the other hand Overlay network is a virtual network that is built on top of an underlay. For example, you can imagine that the links between ISPs that create the Internet formed an underlay network and your Site-to-Site VPN, on top of it, is an overlay.


0

You can use multidimensional parity to correct errors, but the amount of error-correction you get is low for a given amount of parity overhead. This makes it suitable only for situations with very low bit error rates. A two-dimensional parity scheme can correct a single error: Original With error Correction 1 0 1 1 1 1 0 1 1 1 0 0 0 0 0 ...


2

Single-bit parity can only detect errors and it can only detect single-bit errors. Multi-bit errors can cancel each other out, resulting in undetected errors. In information theory, a single bit can only hold the simple information "data correct" or "data incorrect". Using multi-bit ECC codes on larger bit groups is far superior as it can correct single-bit ...


3

Parity use to detect errors, not for correcting.Especially it is used to validate Integrity of Data. If parity check is failed in receiver's end frame will be rejected. Read this article for more details.


0

Zero separation is possible. TLDR Yes you can do it in plain ehternet where there is no any restriction applied. If communication between VMs is based on IP protocol there will be no issue. Even if it plain L2 protocol there is no issue also if protocol can differentiate communication node not only by MAC address(for example IP protocol). Because ARP (...


5

Zac has put a great answer together. But I wanted to add a simplified answer along the same lines. Identical MAC, not within a single layer 2/broadcast domain. There are probably a lot of devices out there with the same MAC address, but because the minimum required separation is at this very low level it doesn't cause issues. Another consideration to ...


22

Suppose you have two NICs with the same MAC address, but not necessarily the same IP address. You can't have that within the same link-layer segment. Identical MAC addresses will disable reliable switching/bridging. What is the least possible separation (in terms of number of switches, routers, different IP subnets etc.) needed that would still allow ...


1

Typically, a TCP responder (here: your SIEM Syslog Server) will send a TCP-RST as a response to a TCP-SYN that tried to reach a (destination) port that was not in LISTENING state. In other words: "Port not open". You may want to check if the intended receiving system is actually configured to accept syslog messages on TCP (most often, Syslog runs on UDP/...


2

Per this document Cisco ASA 5585-X Hardware Installation Guide https://www.cisco.com/c/en/us/td/docs/security/asa/hw/maintenance/5585guide/5585Xhw/overview.html dated December 14 2017: Note Online insertion and removal (OIR) of SSPs and network modules is not supported at this time. Small form-factor pluggable (SFP/SFP+) transceiver, power-supply ...


1

It is highly unlikely that a host will send the same sequence number twice in a row to open a connection. Remember that this is a 32-bit random number, and the RFC specifies that the number should only repeat every four and a half hours or so. By using a random sequence number this way, a delayed SYN can be discovered. What you really have is a four-way ...


3

Something has to set the DSCP values. In a traditional network, that comes from either the end user / application, or intervening network hardware. Unless you have significant control of the device/application -- eg. VoIP phone -- the former can be a very dangerous road. The later is a very complicated, and tedious process. It is this area that machine ...


1

Why is there a need for a MAC address on top of IP address? ... but am pretty sure you could come up with a similar technique for MAC addresses. IPv4 and Ethernet are two independent developments. Therefore a MAC addresses is required for transferring data over Ethernet and a completely different IPv4 address is required for transferring data over ...


6

On the network layer and the data link layer, packets/frames are generally not acknowledged (with few exceptions). The protocols use robust designs but lost packets stay lost. If required, recovery needs to take place on higher layers. Some transport layer protocols acknowledge data (most prominently TCP) while others do not, for instance UDP. Note that ...


4

It depends on the data link protocol. Some obsolete ones, like X.25, do acknowledge frames. 802.11 (WiFi) also does. But Ethernet does not. If a corrupt frame is detected, it is silently dropped.


1

It's perfectly easy to imagine how things would work in a small LAN with a default gateway. Anything which is nearby is broadcastable, everything else has to get sent to the default gateway. This is momre-or-less the functionality inside an ethernet switch: it learns where everything is by listening to ethernet addresses. Any ether address it doesn't know ...


3

Zac67 and Ron Maupin have briefly explained how multiple IP addresses per NIC work, which was probably the intent of the question. Here, I try to explain why one would add a second IP address to a host or gateway. In most cases nowadays, one would normally use multiple VLANs for these situations, with one subnet per VLAN. History VLANs were standardised ...


0

In short Yes, in the service abstraction layer which is your orchestration portion, you can define some policies that these policies than will translate to network policies like QoS.


8

Each interface requires an IP address of its own. Two different networks (subnets) require two different IP addresses, one from each network. You can bind multiple IP addresses to a single interface. When interfaces are bonded in some ways they can share an IP address (or address pool). A physical interface configured with multiple VLANs (on a trunk) ...


11

IP addresses are assigned to layer-3 interfaces (IP is a layer-3 protocol), either physical or virtual, and each interface can have multiple IP addresses. Multiple IP addresses are even required for IPv6, where you will have a Link-Local address and one or more Global and/or ULA addresses per interface. I will give you an IPv4 example that happens. DHCP is ...


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