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1500 questions
9
votes
4 answers

Recording latency between a controlled startpoint and uncontrolled endpoint

This might be a very basic troubleshooting question, but it's worth asking to make sure I'm testing things the correct way and interpreting results effectively. I have a controlled start point (a server cluster under my control) and an uncontrolled…
Sean Long
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3 answers

Why does "show adjacency" take so long to run?

Why does the "show adjacency" command take so long to run (in the order of minutes) on Cisco IOS Software, 7200 Software (C7200P-SPSERVICESK9-M), Version 12.4(4)XD5, RELEASE SOFTWARE (fc1)? The router is an Internet edge router running BGP? What…
generalnetworkerror
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9
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1 answer

How DHCP OFFER unicast works?

In the DHCP discover packet, the source IP address field is 0.0.0.0 which means the client does not have an IP address yet. But, in the DHCP offer packet, an unicast address (which will be allocated for this client) is specified as destination…
Ezio
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9
votes
2 answers

3750G Switch Buffer Monitoring

We have put some 3750Gs in a stack for our DC access switches. We are concerned that these won't be able to handler higher data loads as traffic increases due to their limited buffers. What statistic/s and/or specific SNMP OID's should we be…
Tim
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9
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1 answer

What do the parentheses "()" after objects mean in Cisco ASA ACLs?

I have encountered something I'm not familiar with in a customer's configuration, I know that the "(hitcnt=324165)" at the end of every rule in "show access-list" points to rule usage, hit count. But in this output of show access-list I'm also…
Harnik
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8
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1 answer

Unidirectional Packet Loss

Recently after upgrading several MetroE circuits (L2 connectivity) from 100Mbps to 1Gbps, I noticed that large file transfers fail between some sites; however, the transfer only fails in direction. For instance, consider the following example. From…
Paul Garrett
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8
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2 answers

Moving internally allocated VLANs

A VLAN I need to use is allocated for internal usage (as per vlan internal allocation policy ascending). I can't (easily) move the traffic over to another VLAN for various practical reasons. I was therefore wondering if there's a trivial way to…
Jan
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8
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3 answers

Can 40GBASE-LR4 be used for 4x10G?

I have a 40GBASE-SR4 QSFP transceiver which can be used for 4x10G SFP+ communications using a 40G QSFP+ to 4x10G SFP+ multi-mode optical spliter. I am looking for an LR (single-mode) equivalent of this SR transceiver, but can't find any. I fear that…
Randomblue
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8
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2 answers

Where is Cisco Hardware dCEF's adjacency table stored?

For Cisco Hardware dCEF, based on some documents published on Cisco website, at the ingress line card/interface, conceptually it looks up the FIB with dst IP address, and gets a pointer to an adjacency table entry, where L2 rewrite information is…
wei
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8
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4 answers

How to signal a VPLS multihoming change to a L2 CE device

We have the following setup: Two MX routers connect to the same L2 site. Loop protection / redundancy is done via VPLS multihoming. On the other end are two switches (EX4200 for example). When the blue link fails the two switches and the rest of…
Sebastian Wiesinger
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8
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5 answers

Switchport mode access VLAN & switchport mode trunk on one interface

Googling around to see if this setup on one port is correct (it doesn't look right to me), I'm not really seeing a straightforward answer. There is an interface with the following configuration: ! interface GigabitEthernet1/0/3 description Uplink…
PenguinCoder
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8
votes
2 answers

Duplicate IP Address Prevention?

Yesterday a laptop crashed the network because the IP address of the computer was the same as the router. Computers in the network were reaching the laptop instead of the router. Is there anyway to prevent this from happening? We currently have a…
Patrick Dubois
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8
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3 answers

Can I announce the same block of /24 given to me by ARIN at two different locations?

The setting: Two locations I'm trying to connect. I have a /24 address block from ARIN Both location have the Same ISP. The Question: Can I announce the same /24 address block at the HQ location to Lumen? Can I announce the same /24 address block…
13months
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8
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6 answers

How Does A Layer 2 Switch Differentiate Between Different Networks?

I know that different IP-based networks can be connected to the same layer-2 switch. and I know each network's nodes can communicate just fine, however, no normal traffic can occur between two nodes on two different networks. My understanding is…
Shadi
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8
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3 answers

BGP - Soft Reset Outbound & Verification

My understanding of the command: clear ip bgp * soft out is that the router on which the command is issued will re-advertise everything it knows about BGP to it's neighbors. As I see it, it's as if the two routers are creating a brand new…
BrianK
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