Re: delay and delay [7:20926]
EIGRP uses minimum bandwidth and total delay to compute metric (at lest in its default configuration). I'm a little bit confused: delay of each interface is inversely proportional to the configured interface bandwidth, so It seems that EIGRP metric is affected only by configured bandwidth (f(bandwidth)+ sum of f(1/bandwidth)): is this correct? Please give a look to the following output. I see in the first subinterface BW 3264 and in the second one BW 2544, but the same DLY value: 80. Rome-7206vxr#sh int atm2/0.1 ATM2/0.1 is up, line protocol is up Hardware is ENHANCED ATM PA Description: P-to-P PVC with Milan Internet address is 213.x.y.14/30 MTU 4470 bytes, BW 3264 Kbit, DLY 80 usec, reliability 255/255, txload 1/255, rxload 4/255 Encapsulation ATM 0 packets input, 0 bytes 0 packets output,0 bytes 99302 OAM cells input, 99302 OAM cells output Rome-7206vxr#sh int atm2/0.2 ATM2/0.2 is up, line protocol is up Hardware is ENHANCED ATM PA Description: P-to-P PVC with London Internet address is 213.x.y.74/30 MTU 4470 bytes, BW 2544 Kbit, DLY 80 usec, reliability 255/255, txload 1/255, rxload 4/255 Encapsulation ATM 0 packets input, 0 bytes 0 packets output,0 bytes 99121 OAM cells input, 99121 OAM cells output You suggest you can tweak the interface bandwidth and my english is awful: what does it mean? Thank you and have a nide day to all, Teresa Teresa Presutto Grapes Italia S.p.A. Italy Network Development Via Chiana, 1 - 00198 Rome (Italy) Tel +39 06 84550.1, fax +39 06 84550.640, mobile +39 348 4719450 - Original Message - From: Priscilla Oppenheimer To: [EMAIL PROTECTED] Sent: Monday, September 24, 2001 9:41 PM Subject: Re: delay and delay [7:20926] With ping, delay is actually measured. The router reports how long it takes to get replies. EIGRP delay is not dynamically measured. Delay of each interface is inversely proportional to the configured interface bandwidth. Total delay for an EIGRP route is a sum of each interface delay, as reported in EIGRP Updates. If you want EIGRP's delay to be somewhat more realistic, you can tweak the interface bandwidth. Priscilla At 02:06 PM 9/24/01, TP wrote: Group, what is the relation (if any) between the total delay I see in sh ip eigrp topology and the total delay I see in a simple ping? From show eigrp topology I see total delay associated to a point-to-point atm pvc lower than total delay showed for a E1 hdlc (between the same routers, 1 hop). If a make an extended ping I experience a lower delay with E1 than pvc atm (and, to be honest, this is what I'd like to see) Thanks in advace, Teresa Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=20972t=20926 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: delay and delay [7:20926]
At 11:42 AM 9/25/01, TP wrote: EIGRP uses minimum bandwidth and total delay to compute metric (at lest in its default configuration). I'm a little bit confused: delay of each interface is inversely proportional to the configured interface bandwidth, so It seems that EIGRP metric is affected only by configured bandwidth (f(bandwidth)+ sum of f(1/bandwidth)): is this correct? No, I think I misspoke. Sorry. You can configure both bandwidth and delay for an interface. Just configuring bandwidth doesn't affect delay. You would have to configure it separately. (Since delay is inversely proportional to bandwidth, I would think it would change automatically when bandwidth is changed, but it doesn't.) The metric = [K1 * bandwidth + (K2 * bandwidth) / (256 - load) + K3 * delay] * [K5 / (reliability + K4)] The K values can be configured with the metric weights command, although there's generally no need to change them. Priscilla Please give a look to the following output. I see in the first subinterface BW 3264 and in the second one BW 2544, but the same DLY value: 80. Rome-7206vxr#sh int atm2/0.1 ATM2/0.1 is up, line protocol is up Hardware is ENHANCED ATM PA Description: P-to-P PVC with Milan Internet address is 213.x.y.14/30 MTU 4470 bytes, BW 3264 Kbit, DLY 80 usec, reliability 255/255, txload 1/255, rxload 4/255 Encapsulation ATM 0 packets input, 0 bytes 0 packets output,0 bytes 99302 OAM cells input, 99302 OAM cells output Rome-7206vxr#sh int atm2/0.2 ATM2/0.2 is up, line protocol is up Hardware is ENHANCED ATM PA Description: P-to-P PVC with London Internet address is 213.x.y.74/30 MTU 4470 bytes, BW 2544 Kbit, DLY 80 usec, reliability 255/255, txload 1/255, rxload 4/255 Encapsulation ATM 0 packets input, 0 bytes 0 packets output,0 bytes 99121 OAM cells input, 99121 OAM cells output You suggest you can tweak the interface bandwidth and my english is awful: what does it mean? Thank you and have a nide day to all, Teresa Teresa Presutto Grapes Italia S.p.A. Italy Network Development Via Chiana, 1 - 00198 Rome (Italy) Tel +39 06 84550.1, fax +39 06 84550.640, mobile +39 348 4719450 http://www.grapesnet.com - Original Message - From: Priscilla Oppenheimer To: [EMAIL PROTECTED] Sent: Monday, September 24, 2001 9:41 PM Subject: Re: delay and delay [7:20926] With ping, delay is actually measured. The router reports how long it takes to get replies. EIGRP delay is not dynamically measured. Delay of each interface is inversely proportional to the configured interface bandwidth. Total delay for an EIGRP route is a sum of each interface delay, as reported in EIGRP Updates. If you want EIGRP's delay to be somewhat more realistic, you can tweak the interface bandwidth. Priscilla At 02:06 PM 9/24/01, TP wrote: Group, what is the relation (if any) between the total delay I see in sh ip eigrp topology and the total delay I see in a simple ping? From show eigrp topology I see total delay associated to a point-to-point atm pvc lower than total delay showed for a E1 hdlc (between the same routers, 1 hop). If a make an extended ping I experience a lower delay with E1 than pvc atm (and, to be honest, this is what I'd like to see) Thanks in advace, Teresa Priscilla Oppenheimer http://www.priscilla.com [EMAIL PROTECTED] Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=21029t=20926 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: delay and delay [7:20926]
I like the way Jeff Doyle writes this IGRP EIGRP metric formulas. It looks to me that all other ways just confuse people. At least that is my opinion, which don't have to be true. For example, Priscilla wrote: The metric = [K1 * bandwidth + (K2 * bandwidth) / (256 - load) + K3 * delay] * [K5 / (reliability + K4)] but if someone try to calculate EIGRP metric based on above formula, with specified minimum bandwidth and total delay, as reported with show ip eigrp topology a.b.c.d he/she won't get the correct result, because bandwidth and delay in above formula aren't bandwidth and delay ! Instead, much better way is to say the metric is (lets assume K1=K3=1 and K2=K4=K5=0, for simplicity): metric = 256 * ( K1 * EIGRP_BANDWIDTH + K3 * EIGRP_DELAY ) where EIGRP_BANDWIDTH = 10^7 / min_bandwidth_on_path_in_kbps EIGRP_DELAY = total bandwidth in 10uS (10uS is unit in which delay is actually configured on the interface) Now, lets see example: #show ip eigrp topology 192.168.224.3 255.255.255.255 IP-EIGRP topology entry for 192.168.224.3/32 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 156160 Routing Descriptor Blocks: 65.195.140.4 (FastEthernet0/0), from 65.195.140.4, Send flag is 0x0 Composite metric is (156160/128256), Route is External Vector metric: Minimum bandwidth is 10 Kbit Total delay is 5100 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 1 External data: Originating router is 192.168.224.3 AS number of route is 0 External protocol is Connected, external metric is 0 Administrator tag is 0 (0x) So, EIGRP_BANDWIDTH = 10^7 / 10^5 = 10^2 = 100 EIGRP_DELAY = 5100 / 10 = 510 metric = 256 * ( 100 + 510 ) = 256 * 610 = 156160 , exactly as reported by show ip eigrp topology and show ip route command. Help this clear confusion :) Regards, Sasa Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=21068t=20926 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: delay and delay [7:20926]
Priscilla Oppenheimer wrote: No, I think I misspoke. Sorry. You can configure both bandwidth and delay for an interface. Just configuring bandwidth doesn't affect delay. You would have to configure it separately. (Since delay is inversely proportional to bandwidth, I would think it would change automatically when bandwidth is changed, but it doesn't.) This is perhaps bordering on semantics, but as I understand delay (i.e., latency) it has no dependence on bandwidth. Delay is how long it takes the first bit of the frame to arrive at the destination. Whereas bandwidth determines how closely spaced the bits are and how long it takes until the last bit of the frame arrives. So to get the best approximation of delay, a ping should send the minimum size test data. (E)IGRP uses static typical values for the transit time of a given data link. A 10Mb Ethernet is assumed to take 1 ms and a WAN link is assumed to take 20 ms (your geography may vary :-) Marty Adkins Email: [EMAIL PROTECTED] Mentor Technologies Phone: 240-568-6526 133 National Business Pkwy WWW: http://www.mentortech.com Annapolis Junction, MD 20701Cisco CCIE #1289 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=21090t=20926 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
delay and delay [7:20926]
Group, what is the relation (if any) between the total delay I see in sh ip eigrp topology and the total delay I see in a simple ping? From show eigrp topology I see total delay associated to a point-to-point atm pvc lower than total delay showed for a E1 hdlc (between the same routers, 1 hop). If a make an extended ping I experience a lower delay with E1 than pvc atm (and, to be honest, this is what I'd like to see) Thanks in advace, Teresa Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=20926t=20926 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: delay and delay [7:20926]
With ping, delay is actually measured. The router reports how long it takes to get replies. EIGRP delay is not dynamically measured. Delay of each interface is inversely proportional to the configured interface bandwidth. Total delay for an EIGRP route is a sum of each interface delay, as reported in EIGRP Updates. If you want EIGRP's delay to be somewhat more realistic, you can tweak the interface bandwidth. Priscilla At 02:06 PM 9/24/01, TP wrote: Group, what is the relation (if any) between the total delay I see in sh ip eigrp topology and the total delay I see in a simple ping? From show eigrp topology I see total delay associated to a point-to-point atm pvc lower than total delay showed for a E1 hdlc (between the same routers, 1 hop). If a make an extended ping I experience a lower delay with E1 than pvc atm (and, to be honest, this is what I'd like to see) Thanks in advace, Teresa Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=20936t=20926 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
