• Tag : ARP


7124FX Adding static entry to ARP cache

Hi, I have an Arista 7124FX switch, and I’m trying to add a static ARP entry to the ARP cache with the arp <ipv4_addr> <mac_addr> arpa command, and, while this does not give an error, the arp cache still remains seemingly empty when I use the show arp command. Is there anything else I should have done to add entries to the cache?

Support for neighbor cache capacity

Description ARP and IPv6 Neighbor Discovery use a neighbor cache to store neighbor address resolutions.  The capacity of the neighbor cache is determined by the resources and capabilities of the device platform. The neighbor cache capacity feature adds a means to specify a per-interface capacity for the neighbor cache. A neighboring device, through misconfiguration or maliciousness, can unfairly use a large number of address resolutions. This feature can help to mitigate this over-utilization. Platform compatibility This feature is platform independent. Configuration The cache capacity feature is configured on any layer 3 interface with switch(config)#interface ethernet1 switch(config-if-Et1)#arp cache dynamic capacity <capacity>...
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VXLAN Unresolved ARPs to

We have stand for test VXLAN between different DCs (schema in attachment). All Leafs connected to CVX server on each DC. And each CVX connected between themeslaves via BGP EVPN. For test in each leaf was connect server with linux and configured port on access VLAN100. Next step I configure assotiation VLAN100 and VNI25100. MAC Lerning good work and on both leaf I see mac-addreses. Connection for vxlan configured in GRE tunnel and has good L3 connectevless. But traffic has no on VNI 25100. I tried to debug this problem and discovered: show vxlan config-sanity category result detail ———————————- ——–...
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Pause – Revisit the Fundamentals – ARP

Introduction Wow, networking technology really does continue to march along. If you wanted to be a lifelong learner you definitely picked a great speciality. And face it, we all know the cool kids are the Network Engineers. In this article we’re not going to take a bunch of packet captures nor analyze the outputs of a dozen ‘show’ commands. There are plenty of documents for that already. Rather, this document and the entire Pause series, looks to take a step back and feed your team’s banter about ‘What problem are we trying to solve?’ Evolving Tech New Layer 1 technologies...
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VXLan, MLAG and duplicate ARP

We having an issue that we believe is related to receiving duplicate ARP requests. We’ve got nodes (part of openstack) connected to a pair of 7060 switches using MLAG, these 7060 switches then join a VXLan to connect to other pairs of 7060 switches where other nodes exist. The behaviour we’re seeing with ARP requests is that the broadcast is being flooded to the VTEP that is on both switches in the MLAG group, this is then being forwarded down both legs to the node, so the node sees the request twice. This seems to be confusing the OVS running...
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static ARP inspection – configure IP-MAC bindings?

Based on TOI: https://eos.arista.com/eos-4-15-0f/static-arp-inspection/ static ARP inspection is now Available but how can we add and remove IP-MAC paars? on IP Source Guard this is documented: https://eos.arista.com/eos-4-15-2f/ip-source-guard/ but not on Static IP Inspection, did i miss something? Thanks for helping

How to Troubleshoot Ineffective Intrusion Prevention

Introduction This article describes how to troubleshoot a device that is not being successfully prevented by Arista WIPS functionality. Prerequisites Access to CloudVision WiFi with administrative privileges. Solution Intrusion Prevention techniques are used to quarantine a device that poses a WiFi threat and block it from accessing the network. However, there are some scenarios, when wireless prevention may not be successful: If the wireless connection uses Management Frame Protection (MFP) e.g. if an Authorized or guest client is connected to an external Access Point (AP) with MFP enabled. If the client is outside the prevention range of all Arista APs....
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Why do I see Many ARP Packets Coming from Arista Sensors on My Network?

Introduction This article describes one of the techniques used by Arista Sensors to determine wired connectivity of the Access Points that are visible in the RF vicinity. This technique leverages ARP request packets sent by the sensor from its wired side MAC address on each VLAN. ARP request packets are sent to Layer 2 broadcast address. Prerequisites Arista WIPS Sensor and Wireshark How it Works The Arista Marker packets are formatted as gratuitous ARP Requests i.e., sensor requests resolution of its own IP address. The sensor injects the ARP marker packets on VLANs that it is monitoring and they remain...
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