The two sides on Monday also agreed on a set of principles for negotiating a full peace agreement.
The deals were signed by Mustafa Osman Ismail, a Sudanese presidential adviser, and Musa Mohamed Ahmed, the head of the Eastern Front.
"We are only at the beginning of the road, we have a long way to go," Ismail said.
"The Eastern Front will continue discussions for a lasting peaceful settlement," added Ahmed.
The talks began on June 13 after Omar al-Beshir, the Sudanese president, and his Eritrean counterpart, Assaias Afeworki, held a rare meeting in Khartoum, which analysts believe boosted the chances of a truce.
Several Libyan-sponsored initiatives had failed to end the sporadic fighting that has plagued Sudan's impoverished eastern states, where the rebels hold a strip of territory along the Eritrean border.
The Eastern Front rebel alliance is made up of the region's largest ethnic group, the Beja and Rashidiya Arabs.
It has similar aims to its counterparts in the western Sudanese region of Darfur - greater autonomy and control over the area's resources.
The rebel Justice and Equality Movement (JEM), active in Darfur, has also emerged as a key player in eastern Sudan.
It demands a seat at the presidency as part of any peace settlement, but has not been invited to the Asmara talks.