8 votes
Accepted

How to debug L1 Auto negotiation issues?

Likely it's the cable. While there were some issues with the Autonegotiation standard very early on, they've been resolved for decades and anything from 2000+ can't be affected. Generally, leave ...
Zac67's user avatar
  • 84.4k
7 votes

1 x 40G QSFP to 4 x 10G SFP+ Can these 4 x 10G breakouts go to different hosts?

A 1x40G QSFP port can be fanned-out to 4x10G SFP+ ports. You need to configure that 40G port as 4 Tengig ports in the switch. The break out cables on the other end can go to different hosts.
Venkat Sankaran's user avatar
5 votes

Cisco Nexus 5500 7.3.(3)N1(1) tcl script

Any ideas? Yes. Looks like your ping syntax is wrong. To verify, exit the TCL shell and trying running the same ping command from your script substituting in an appropriate value: ping vrf XYZ 10.xx....
YLearn's user avatar
  • 27.3k
5 votes

Difference between N3K and N5K

Be sure to understand the limitations of the N5K https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5500/sw/Verified_Scalability/730N11/b_5500_Verified_Scalability_730N11/...
Marc 'netztier' Luethi's user avatar
5 votes
Accepted

Cisco Nexus 5672, not showing ARP records for VLANs

ARP is only required if a device needs to know the MAC address of an IP address. If the route between the IP address of the switch to some device is via a router (which it will be if you have a ...
jonathanjo's user avatar
  • 16.2k
5 votes

How to debug L1 Auto negotiation issues?

Some Cisco Platforms (most access switch types of the Catalyst 2900/3600/3800 series and their older siblings too) support these commands: interface GigabitEthernet M/NN ... ! select which set of ...
Marc 'netztier' Luethi's user avatar
4 votes

1 x 40G QSFP to 4 x 10G SFP+ Can these 4 x 10G breakouts go to different hosts?

The Cisco 5696Q supports this according to the Cisco datasheet. There are instructions on how to configure it. These 4 ports will behave like individual ports but be aware that they are the same QSFP ...
Sebastian Wiesinger's user avatar
4 votes
Accepted

Jumbo frame on Nexus 5k

Yes you can, you just have to classify the traffic. Here is an example where we classify iSCSI into its own class. The class-default class will match any other traffic. class-map type qos match-all ...
John K.'s user avatar
  • 969
3 votes

Difference between N3K and N5K

Start from this page for the 5500's verified scalability and this for the 3K. In short (...and as mentioned above) the L3 switching module on the 5500 is basically a router on a 16x10GE switch. The ...
rnxrx's user avatar
  • 6,114
3 votes

Cisco Nexus 5500 7.3.(3)N1(1) tcl script

This is the script template I made and use to do a ping sweep followed by showing the ARP table for results. You can modify this to meet you needs. ----- BEGIN NX-OS TCL SCRIPT ------ tclsh for {set ...
Jesse P.'s user avatar
  • 4,690
3 votes
Accepted

Netflow vs sampled netflow

For traffic analysis sampled netflow is often used, because 1:1 sampling (or non-sampled) netflow can be quite a burden on both the router sending the flow data and on the flow receiver. Most setups I'...
Teun Vink's user avatar
  • 17.4k
3 votes

Server1 cannot reach Server2, both connected to the same switch

tl;dr if I traceroute Server1, I get a reply not from the server itself but from its default gateway. Why is that and how does it work. The gateway is unable to ARP the destination IP address. ...
Zac67's user avatar
  • 84.4k
3 votes
Accepted

applying licensing to Nexus 5k

No, you do not need to reboot the switch!
Gopalakrishnan Mallappan's user avatar
3 votes

Core Dropped VLANs and Pickedu up Access VLANS?

This command: no switchport trunk allowed vlan 64,68 probably didn't do what you think it does. The switch probably read that as no switchport trunk allowed vlan which would remove all vlans on ...
Special Circumstances's user avatar
2 votes

Cisco Nexus 5k EIGRP Configuration

I could be wrong here, but it looks to me like both switches have the same subnets defined. If I'm DUAL I'm going to remove a route I learn from you if I already have that subnet locally connected.
BlackMagix's user avatar
2 votes

DCNM Lincense Allocation

Download the license pack file that you received from Cisco <L-DCNM-L-N5K-K9=> into a directory on the server system. Copy the license file into INSTALL_DIR/dcnm/licenses directory. On a ...
Gadeliow's user avatar
  • 3,444
2 votes

Fabricpath or vpc back to back

Both approaches will work and are actively documented and supported. FP starts to really have a significant advantage if you have more than the 4 switches in your design and, particularly, if you ...
rnxrx's user avatar
  • 6,114
2 votes

Fabricpath or vpc back to back

You don't need fabricpath to run a vPC+ from a FEX. Fabricpath is really only useful in large data centers where you have a multiple tier topology (Core, Aggregation, Access). In a smaller setup ...
John K.'s user avatar
  • 969
1 vote

Difference between N3K and N5K

The N3k is suitable for your application. The main advantages of the N5k are the ability to use fabric extenders (very similar to stacking tbh) and to combine fibre channel & Ethernet for networks ...
Jeff Wheeler's user avatar
  • 5,469
1 vote
Accepted

Cisco Nexus 5548 802.1x Guest-VLAN not available

I've learned that the switch needs to be on version 7.2(0)N1 at minimum. Per the release notes; this is the version in which "Dynamic VLAN Based on MAC-Based Authentication (MAB)" was added. Once I ...
dutsnekcirf's user avatar
1 vote

How to debug L1 Auto negotiation issues?

1000BaseT uses all 4 pairs in the cable bidirectionally, so a failure in pair 1 or 4 should theoretically affect both switch and host and force a fallback to 100 Mb/s. A failure in pair 2 or 3 would ...
grahamj42's user avatar
  • 360
1 vote

Unbalanced port-channel utilization

The load balancing on a port channel is per flow. All the traffic in a single flow will use the same port channel member. Each flow is limited to a single physical link, but different flows will use ...
Ron Maupin's user avatar
  • 99.6k
1 vote
Accepted

add local route to vPC member

resolution was to ip route 1.1.1.0/30 [IP on 5k-1]
Rex Sheffield's user avatar
1 vote

1 x 40G QSFP to 4 x 10G SFP+ Can these 4 x 10G breakouts go to different hosts?

40G QSFP+ cables can be divided into two types—40G QSFP+ to QSFP+ cable or 40G QSFP+ to 4SFP+ breakout cable. The 40G QSFP to 4SFP+ breakout cable Can be used in different hosts.
Mark Twain's user avatar

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